Dogs Flashcards

Question

An 8-year old male castrated Labrador Retriever presents for collapsing episodes. You record an ECG, which is shown here. **What is your diagnosis?** Complete heart block Sinus arrest Normal sinus rhythm Atrial premature complexes Ventricular premature complexes

Answer 1

Answer: **Complete heart block** The correct answer is complete heart block. The ECG shows frequent P waves and two ventricular escape beats from different foci. Complete heart block typically results from degeneration and fibrosis of the cardiac conduction system. The animal then relies on a slow escape rate, which often results in clinical symptoms of weakness and collapse. Sinus arrest would be seen as periods of flat line on the ECG with no atrial activity; normal sinus rhythm would show conduction of the P waves with QRS complexes following. Ventricular premature complexes is incorrect because the above 2 ventricular beats are escapes, they are not premature. Atrial premature complexes is wrong as the atrial rhythm is normal.

Answer 2

Answer: **Balloon valvuloplasty** Explanation The correct answer is balloon valvuloplasty. This procedure is performed by inserting a catheter into either a jugular vein or a femoral vein and advancing it into the region of stenosis at the pulmonic outflow tract. Once in place, a balloon surrounding the catheter is inflated to stretch the stenotic region open. Surgical valvulotomy or patch grafting is the treatment used for severe cases that cannot be balloon-dilated. *Balloon valvuloplasty is the treatment of choice for pulmonic stenosis in dogs. It involves inserting a catheter through the jugular or femoral vein to the pulmonic outflow tract and inflating a balloon to stretch the stenotic region. Surgical valvulotomy or patch grafting is reserved for severe cases unresponsive to balloon dilation.*

Answer 3

Answer: **strict activity restriction of the dog is very important once medical treatment is initiated** Explanation The correct answer is strict activity restriction of the dog is very important once treatment is initiated. Dogs should be restricted in activity at least 4-6 weeks post treatment to decrease the likelihood of thromboembolic events and to allow the lungs to recover from injury due to worm death. Dogs are not as likely to develop right heart failure after treatment of heartworm disease if they were previously clinically normal. Ivermectin is often used to prevent heartworm disease and for treating microfilariae, but the treatment of choice for adult worms is melarsomine IM. Doxycycline is often used to treat the Wolbachia bacteria that are often found with heartworms, but is ineffective at treating the worms themselves. *Strict activity restriction is crucial once heartworm treatment starts, to reduce thromboembolic events and allow lung recovery post worm death. Dogs clinically normal pre-treatment rarely develop right heart failure afterward. Ivermectin prevents heartworm and treats microfilariae, but melarsomine IM treats adult worms. Doxycycline targets Wolbachia bacteria associated with heartworms, not the worms themselves.*

Answer 4

Answer: Vasopressin. Explanation The correct answer is vasopressin. Epinephrine and phenylephrine are adrenergic vasoconstrictors. Isoproterenol and dobutamine cause vasodilation. Vasopressin (also known as anti-diuretic hormone) is a V-1 receptor, non-adrenergic, vasoconstrictor.

Answer 5

Answer: **Medical management with Beta-Blockers** Explanation The correct answer is medical management with beta blockers. Beta blockers such as atenolol are often used to reduce myocardial oxygen demand, thus reducing the frequency of ventricular arrhythmias. The owners should also be warned that the dog will need prophylactic antibiotics for any situation in which the dog may develop a bacteremia, since it is at high risk of developing infective endocarditis. Balloon dilation by catheterization can be attempted in some patients, but the results are usually no better than medical therapy with beta blockers. Surgical repair is difficult, expensive, and does not give very good results either. There is no indication for furosemide unless the dog is in heart failure. *Medical management with beta blockers, such as atenolol, is the most common treatment for aortic stenosis in dogs. Beta blockers reduce myocardial oxygen demand and ventricular arrhythmias. Prophylactic antibiotics are needed to prevent infective endocarditis. Balloon dilation offers no better results than beta blockers, and surgical repair is challenging and less effective. Furosemide is only indicated for heart failure.*

Answer 6

Answer: **Echocardiogram** The breed, clinical history of syncope, radiographic findings, and auscultation findings are most consistent with aortic stenosis. Echocardiography would be the best method for diagnosing the disease in which you would find left ventricular concentric hypertrophy, stenosis of the aortic outflow tract, and post-stenotic dilatation of the ascending aorta. A Holter monitor is the test of choice for arrhythmogenic right ventricular cardiomyopathy (ARVC) which is also seen in Boxers and causes syncope but does not fit with the physical exam or radiographic findings. Also called Boxer cardiomyopathy, ARVC is a disease associated with fibrofatty infiltrate into the right ventricle resulting in electrical conduction disturbances and resultant VPCs. A CT scan would not add more information, and cardiac motion typically causes resolution problems on thoracic CT scans. The signs are not consistent with heartworm, which is primarily a right heart problem, or with hemolytic anemia, which a Coombs' test might be useful for.

Answer 7

Answer: **Aortic stenosis.** Explanation The correct answer is aortic stenosis. The breed, clinical history of syncope, radiographic findings, and auscultation findings are most consistent with aortic stenosis. Echocardiography would be the best method for diagnosing the disease in which you would find left ventricular hypertrophy, stenosis of the aortic outflow tract, and post-stenotic dilatation of the aorta. Pulmonic stenosis would result in changes in the right heart and pulmonary outflow tract. Myxomatous degeneration of the mitral valve typically occurs in older animals, results in a murmur heard best at the left apex, and would not cause a dilation of the ascending aorta. Boxer cardiomyopathy (or arrhythmogenic right ventricular cardiomyopathy) is principally an electrical disease causing frequent VPCs to occur. Dilation of the heart may occur in 10-15% of cases. The best way to diagnose Boxer cardiomyopathy is with a 24 hour cardiac Holter monitor. The most likely diagnosis is aortic stenosis. The breed, syncope, radiographic findings (mildly enlarged left ventricle and atrium, segmental enlargement of the ascending aorta), and auscultation (4/6 left systolic murmur at heart base) support this. Echocardiography reveals left ventricular hypertrophy, aortic outflow tract stenosis, and post-stenotic aorta dilation. Pulmonic stenosis affects the right heart, myxomatous mitral valve degeneration affects older dogs with a murmur at the left apex, and Boxer cardiomyopathy involves frequent VPCs and is diagnosed with a Holter monitor.

Answer 8

Answer: **Atrial septal defect with systemic hypertension** Explanation The correct answer is atrial septal defect with systemic hypertension. This dog's polycythemia developed due to shunting of venous blood into the arterial circulation (aka right-to-left shunting) leading to hypoxemia and an increased drive for erythropoiesis and secondary polycythemia. This can be caused by any of the other 3 answer choices. An atrial septal defect with systemic hypertension results in oxygenated blood shunting into the venous circulation or left-to-right shunting, which usually does not cause hypoxemia. Atrial septal defect with systemic hypertension cannot explain the findings. This condition causes left-to-right shunting, leading to oxygenated blood entering the venous circulation, not hypoxemia. The dog's polycythemia (hematocrit 70%) suggests right-to-left shunting, leading to hypoxemia and increased erythropoiesis. This can be caused by PDA with pulmonary hypertension, atrial septal defect with tricuspid stenosis, or Tetralogy of Fallot.

Answer 9

Answer: **Surgical ligation is the most appropriate form of treatment for a cylinder-shaped PDA** Explanation The correct answer is surgical ligation of the PDA is the most appropriate form of treatment. A large cylindrical PDA is unlikely amenable to closure via traditional coil embolization. Most canine PDAs are funnel-shaped with the smaller end of the funnel attached to the pulmonary artery, and the wider end attached to the aorta. The funnel shape is what allows the coils to lodge in place and cause closure of the PDA. Coils would not stay in place in a large, cylindrical PDA, so surgical ligation is the treatment of choice for this patient. There are newer nickel-titanium devices (Amplatz Canine Ductal Occluder) that show promise for minimally-invasive closure of PDAs which do not taper, but this answer was not provided. Ameroid constrictor rings are typically used for ligating hepatic shunts, and not for PDAs. Medical management with diuretics and heart drugs are only indicated prior to correction of the PDA if the dog is in heart failure. Surgical ligation is the most appropriate treatment for a large, cylinder-shaped PDA. Traditional coil embolization is ineffective for cylindrical PDAs, as coils need a funnel shape to lodge properly. The newer Amplatz Canine Ductal Occluder might be effective but wasn't an option. Ameroid constrictor rings are for hepatic shunts, and medical management with furosemide and enalapril is only for pre-correction heart failure.

Answer 10

Answer: **Ivermectin once a month.** Explanation The correct answer is ivermectin once monthly. Diethylcarbamazine (DEC) can be used to prevent heartworm, but is administered once daily. Milbemycin oxime is another preventative used once monthly.

Answer 11

Answer: **Propofol.** Explanation The correct answer is propofol. Ketamine causes an increase in heart rate and blood pressure. It is considered seizureogenic and has poor muscle relaxation effects, however it provides good analgesia. Thiopental is an ultra fast acting thiobarbiturate that causes an increased heart rate, increased blood pressure, and decreased cardiac contractility. It is also an arrhythmogenic agent. Morphine is an opioid that causes bradycardia. Propofol does not result in any significant cardiac changes. It is ultra-short in duration, can cause apnea and myoclonus, and is considered anticonvulsive. It may cause a mild bradycardia but you mainly see that when used in combination with other opiates. More recently propofol has been associated with myocardial depression and hypotension in critically ill dogs and may not be the induction agent of choice as a result. Despite these findings, propofol still has the least effect on heart rate. *Propofol has the least effect on heart rate. Ketamine increases heart rate and blood pressure, Thiopental increases heart rate and blood pressure but decreases cardiac contractility, and Morphine causes bradycardia. Propofol primarily causes mild bradycardia when combined with other opiates and has minimal cardiac impact, making it the best option regarding heart rate stability.*

Answer 12

Answer: **Diltiazem slows the heart by inhibiting the influx of calcium into the myocardial cells.** Explanation The correct answer is diltiazem slows the heart by inhibiting the influx of calcium into the myocardial cells. Diltiazem is a calcium channel blocker used to slow the heart to treat supraventricular tachycardias, hypertrophic cardiomyopathy, and hypertension. *Diltiazem slows the heart by inhibiting the influx of calcium into myocardial cells. It is a calcium channel blocker used to manage supraventricular tachycardias, hypertrophic cardiomyopathy, and hypertension. It does not antagonize beta adrenergic receptors or act as a beta adrenergic agonist.*

Answer 13

Answer: **Acanthocheilonema reconditum** Explanation The correct answer is Acanthocheilonema reconditum (previously Dipetalonema reconditum). Acanthocheilonema reconditum is a blood parasite that looks similar to the microfilariae of Dirofilaria immitis, the agent of Heartworm disease. The two parasites must be differentiated because Acanthocheilonema reconditum is not pathogenic and is therefore not treated. Uncinaria stenocephala, Strongyloides stercoralis, and Filaroides osleri would not be found in the blood.

Answer 14

Answer: **it is a direct measure of blood pressure in the cranial vena cava** Explanation The correct answer is it is a direct measure of blood pressure in the cranial vena cava. Venous blood volume, venous vessel tone, and cardiac output determine the CVP. CVP is an estimate of preload, not a direct measurement. Cardiac output is one of the factors along with venous tone and venous blood volume in obtaining CVP. Afterload is the force against which the myocardium must contract. *Central venous pressure (CVP) is a direct measure of blood pressure in the cranial vena cava. It is influenced by venous blood volume, venous vessel tone, and cardiac output. CVP estimates preload but does not directly measure it. Afterload is the resistance against which the myocardium contracts.*

Answer 15

Answer: **First degree AV block** Explanation The correct answer is first degree AV block as this is a very subtle prolongation between the P and the R wave which can usually only be recognized by evaluation of an ECG strip. *First degree AV block is least likely to be ausculted in a dog, as it involves a subtle prolongation between the P and R wave detectable only via ECG. Other abnormal heart sounds like atrial fibrillation, gallop rhythm, and sinus arrhythmia are more easily ausculted.*

Answer 16

Answer: **Left atrial and left ventricular enlargement with pulmonary hyperperfusion** Explanation The correct answer is left atrial and left ventricular enlargement with pulmonary hyperperfusion. In dogs with a VSD, the shunt occurs during systole when both ventricles are contracting so blood is shunted from the left ventricle almost directly into the pulmonary artery. The right ventricle acts as a conduit between the left ventricle and pulmonary artery and is less commonly affected by the shunted blood. The excess blood flow is found in the pulmonary vasculature, left atrium, and left ventricle, thus enlarging these structures. *The most likely radiographic appearance for a dog with a larger left to right ventricular septal defect and advanced sequelae is left atrial and left ventricular enlargement with pulmonary hyperperfusion. In VSD, blood shunts from the left ventricle to the pulmonary artery during systole, causing excess blood flow in the pulmonary vasculature, left atrium, and left ventricle, enlarging these structures.*

Answer 17

Answer: **Mitral valve prolapse.** Explanation The correct answer is mitral valve prolapse. Note how the mitral valve bends back into the left atrium consistent with mitral valve prolapse. The valve is also thick and mitral regurgitation is likely, which fits with the heart murmur reported. The left ventricular lumen is dilated and walls appear of normal thickness, so concentric hypertrophy is not present. The pulmonic valve is not seen in this image plane. The right ventricle is not well seen either, but in the very near field, the right ventricular wall appears normal. What can be seen of the tricuspid valve does not appear to have any vegetations consistent with endocarditis. *The echocardiogram shows mitral valve prolapse, evidenced by the mitral valve bending back into the left atrium. The valve is thickened, likely causing mitral regurgitation, consistent with the reported heart murmur. The left ventricular lumen is dilated with normal wall thickness, ruling out concentric hypertrophy. The pulmonic valve and right ventricle are not visible, and the tricuspid valve lacks vegetations indicative of endocarditis.*

Answer 18

Answer: **Eccentric hypertrophy of the left atrium and left ventricle** Explanation The correct answer is eccentric hypertrophy of the left atrium and left ventricle. Mitral regurgitation is the process of blood flowing back from the left ventricle to the left atrium due to a defect in the valve. The excess blood flow causes volume overload of the left atrium leading to eccentric hypertrophy or dilation of the chamber. The excess blood volume will then return to the left ventricle during the next diastole, resulting in dilation and eccentric hypertrophy of the left ventricle as well. Concentric hypertrophy occurs in cardiac chambers when they are pressure overloaded, such as in the case of pulmonic stenosis or aortic stenosis. *Mitral regurgitation in dogs leads to eccentric hypertrophy of the left atrium and left ventricle. The regurgitation causes volume overload, resulting in dilation and eccentric hypertrophy of the left atrium. This excess blood then flows into the left ventricle during diastole, causing its dilation and eccentric hypertrophy. Concentric hypertrophy is associated with pressure overload conditions like pulmonic or aortic stenosis.*

Answer 19

Answer: **Polycythemia** Explanation Tetralogy of Fallot is a congenital defect of the heart which includes pulmonic stenosis (not aortic stenosis), dextro-positioned aorta (over-riding), RIGHT ventricular hypertrophy, and a ventricular septal defect. It causes shunting of venous blood across the VSD into the arterial circulation which leads to hypoxemia, and an increased drive for erythropoiesis, causing polycythemia. Affected animals tend be underdeveloped in size and have a history of exercise intolerance, dyspnea, tachypnea, or syncope due to hypoxemia. Thoracic radiographs usually show a normal to mildly enlarged cardiac silhouette with right ventricular enlargement and pulmonary hypoperfusion due to the shunting of venous blood into the arterial circulation. *Polycythemia is consistent with Tetralogy of Fallot in dogs. This congenital defect includes pulmonic stenosis, dextro-positioned aorta, right ventricular hypertrophy, and a ventricular septal defect, leading to venous blood shunting into the arterial circulation. This results in hypoxemia, driving erythropoiesis and causing polycythemia. Affected dogs often exhibit exercise intolerance, dyspnea, tachypnea, or syncope, with thoracic radiographs showing a normal to mildly enlarged cardiac silhouette, right ventricular enlargement, and pulmonary hypoperfusion.*

Answer 20

Answer: **To increase arterial blood pressure** Explanation The correct answer is to increase blood pressure. High doses of dopamine are used as an alpha agonist to increase peripheral resistance and increase blood pressure. It is often used during anesthesia and emergency situations to alleviate hypotension. *Dopamine is often used to increase arterial blood pressure. At high doses, dopamine acts as an alpha agonist, increasing peripheral resistance and blood pressure. It is commonly administered during anesthesia and in emergency situations to counteract hypotension.*

Answer 21

Answer: Surgical ligation is the most appropriate form of treatment for a cylinder-shaped PDA Explanation The correct answer is surgical ligation of the PDA is the most appropriate form of treatment. A large cylindrical PDA is unlikely amenable to closure via traditional coil embolization. Most canine PDAs are funnel-shaped with the smaller end of the funnel attached to the pulmonary artery, and the wider end attached to the aorta. The funnel shape is what allows the coils to lodge in place and cause closure of the PDA. Coils would not stay in place in a large, cylindrical PDA, so surgical ligation is the treatment of choice for this patient. There are newer nickel-titanium devices (Amplatz Canine Ductal Occluder) that show promise for minimally-invasive closure of PDAs which do not taper, but this answer was not provided. Ameroid constrictor rings are typically used for ligating hepatic shunts, and not for PDAs. Medical management with diuretics and heart drugs are only indicated prior to correction of the PDA if the dog is in heart failure. Surgical ligation is the most appropriate treatment for a large, cylinder-shaped PDA in a 1-year-old German Shepherd Dog. Traditional coil embolization is ineffective for cylindrical PDAs, as coils require a funnel shape to lodge properly. Newer devices like the Amplatz Canine Ductal Occluder show promise but weren't options here. Ameroid constrictor rings are for hepatic shunts, and medical management with diuretics and heart drugs is only for pre-correction heart failure.

Answer 22

Answer: Hypotension. Explanation The correct answer is hypotension. Phenothiazines cause sedation, but do not provide analgesia. They may decrease hematocrit due to splenic sequestration of red blood cells. They decrease the sensitivity of the myocardium to catecholamine-induced arrhythmias. Phenothiazines cause hypotension in dogs. They provide sedation without analgesia, may decrease hematocrit due to splenic sequestration of red blood cells, and decrease myocardial sensitivity to catecholamine-induced arrhythmias.

Answer 23

Answer: Atrial fibrillation Explanation Patients with enlarged atria can develop the arrhythmia atrial fibrillation. Atrial fibrillation is characterized by a rapid irregularly irregular rhythm. Primary atrial fibrillation occurs idiopathically in some large-breed dogs, and patients are usually asymptomatic. Secondary atrial fibrillation is more common and occurs secondary to underlying cardiac disease. Atrial fibrillation is the heart rhythm described by the "tennis shoes in a dryer" sound in a 7-year-old Doberman with dilated cardiomyopathy. It is characterized by a rapid, irregularly irregular rhythm and commonly occurs in dogs with enlarged atria due to underlying cardiac disease.

Answer 24

Answer: Hemangiosarcoma. Explanation The correct answer is hemangiosarcoma. Hemangiosarcoma of the heart has a predilection for the right auricle of dogs, with Golden Retrievers being predisposed. Stabilization of this patient will require pericardiocentesis; prognosis is guarded and may include chemotherapy, pericardiectomy, or rarely auriculectomy. Chemodectoma arises from the ascending aorta and heart base; lymphoma is rare in the heart of dogs and is more commonly metastatic than a single mass. Idiopathic pericardial hemorrhage is incorrect because of the clear evidence of a mass. The likely diagnosis is hemangiosarcoma. Hemangiosarcoma often affects the right auricle in dogs, with Golden Retrievers being predisposed. Stabilization involves pericardiocentesis; prognosis is guarded and may involve chemotherapy, pericardiectomy, or rarely auriculectomy. Chemodectoma arises from the ascending aorta and heart base. Lymphoma in the heart is rare and typically metastatic. Idiopathic pericardial hemorrhage is excluded due to the evident mass.

Answer 25

Answer: Furosemide. Explanation The correct answer is furosemide. Sodium-restricted diets, ACE inhibitors such as enalapril, and diuretics such as furosemide decrease blood volume and preload. ACE inhibitors also reduce afterload by preventing production of angiotensin-ll. a potent vasoconstrictor. Pimobendan is also beneficial in the management of congestive heart failure in the dog due to its positive inotropic effects. Lidocaine is used for treating ventricular arrhythmias. Mirtazapine is an appetite stimulator and not a drug used to treat CHF.

Answer 26

Answer: Mosquito. Dirofilaria immitis or heartworm is the parasite in dogs that resides in the pulmonary artery and can cause congestive heart failure if not recognized and treated. Mosquitoes carrying infective heartworm larvae transmit the infection through bites. The larvae then grow and develop over several months to become sexually mature worms. They then release offspring (microfilariae) into the blood stream.

Answer 27

Answer: No anti-arrhythmic therapy is necessary at this time There are several general guidelines/recommendations regarding treatment of ventricular premature contractions which is what is shown on the ECG strip. These include a heart rate of over 180 bpm, pulse deficits, clinical signs, and VPCs for over 20 seconds in duration. In this case, the heart rate is visible on the recording and clearly not elevated. The patient's physical exam findings are not suggestive of an immediate problem secondary to the arrhythmia. There are many dogs with intermittent VPCs that are not of clinical importance. However, it is recommended that the patient be evaluated regularly and ideally have a consultation with a cardiologist to ensure the progression of heart disease is being minimized. Furosemide is not indicated as there is not an indication that the patient is fluid overloaded or in fulminant heart failure. Mexiletine is a Class IB anti-arrhythmic and is not necessary given the lack of severity in the ECG findings. No anti-arrhythmic therapy is necessary at this time. The ECG shows ventricular premature contractions (VPCs) without clinical signs such as an elevated heart rate over 180 bpm, pulse deficits, or sustained VPCs over 20 seconds. Regular evaluation and cardiologist consultation are recommended to monitor heart disease progression. Furosemide is unnecessary as there's no indication of fluid overload or heart failure. Mexiletine, a Class IB anti-arrhythmic, is also not needed given the mild ECG findings.

Answer 28

Answer: Pacemaker implantation Explanation The correct answer is pacemaker implantation. The rhythm is complete heart block (also known as 3rd degree AV block). There is no consistent PR interval; the ventricular beats are escape beats. Atropine can be considered, but is typically not effective in 3rd degree AV block. The only way to restore a normal heart rate in this patient is by implanting a pacemaker, which will require referral to a cardiologist. Sotalol is a ventricular antiarrhythmic, which would actually be dangerous in this patient because it may suppress the ventricular escape focus. Furosemide and doxycycline will not prove beneficial for this rhythm disturbance. Pacemaker implantation is the treatment of choice for a 6-year-old Beagle with complete heart block (3rd degree AV block), indicated by a heart rate of 25 bpm and an ECG showing no consistent PR interval with escape beats. Atropine is typically ineffective in 3rd degree AV block. Sotalol, a ventricular antiarrhythmic, could suppress the ventricular escape focus, making it dangerous. Furosemide and doxycycline are not beneficial for this rhythm disturbance.

Answer 29

Answer: Mexiletine Explanation The correct answer is mexiletine. The Holter ECG shows a couplet of ventricular premature complexes. If frequent ventricular ectopy is seen, particularly with runs or R-on-T episodes, treatment is advised with oral ventricular antiarrhythmics. Mexiletine is an oral class I antiarrhythmic that is well-tolerated in dogs. Pimobendan improves systolic function, but does not treat arrhythmias. Amlodipine is a calcium channel blocker used for patients with systemic hypertension. Diltiazem is used for supraventricular tachycardias to slow conduction down the AV node. Furosemide is a diuretic used in the treatment of heart failure, it does not have antiarrhythmic properties. The correct treatment recommendation for the arrhythmia is mexiletine. The Holter ECG shows a couplet of ventricular premature complexes, and frequent ventricular ectopy, particularly with runs or R-on-T episodes, warrants treatment with oral ventricular antiarrhythmics. Mexiletine, a class I antiarrhythmic, is well-tolerated in dogs. Pimobendan, amlodipine, diltiazem, and furosemide do not address ventricular arrhythmias and serve different cardiac or hypertensive conditions.

Answer 30

Answer: Mitral and aortic valves Explanation The correct answer is mitral and aortic valves. Dogs with endocarditis are most commonly affected on the mitral and aortic valves. The tricuspid and pulmonary valves are rarely affected in dogs and cats, but are the more common sites of infection in large animal species. The mitral and aortic valves are most commonly affected in dogs with infective endocarditis. In contrast, the tricuspid and pulmonary valves are rarely involved in dogs and cats but are more commonly infected in large animal species. Thus, in a 7-year-old Doberman Pinscher with signs suggestive of endocarditis, focus on the mitral and aortic valves.

Answer 31

Answer: **Pericardiocentesis** The radiograph and findings are consistent with pericardial effusion. Note the markedly enlarged globoid cardiac silhouette on the DV projection. Pericardiocentesis is necessary for therapeutic and diagnostic purposes. Atenolol and furosemide would be contraindicated. While this dog is showing signs of heart failure, furosemide would decrease preload on the heart and make diastolic filling even worse in cases of pericardial effusion. Atenolol would decrease contractility. This is not a case of heartworm. Radiographic signs of heartworm include right sided cardiac hypertrophy and prominent pulmonary arteries. Taurine levels could be measured in dogs with dilated cardiomyopathy but will take days to get back and this dog needs to be treated immediately. If facilities permit, even a brief echocardiogram could be performed to confirm pericardial effusion and/or to guide the pericardiocentesis. *Pericardiocentesis is the appropriate treatment for a 9-year-old Greyhound with a cough, respiratory difficulty, and a markedly enlarged globoid cardiac silhouette on thoracic radiographs, indicating pericardial effusion. Atenolol and furosemide are contraindicated as they would worsen diastolic filling and decrease contractility, respectively. Heartworm test and taurine level measurement are unnecessary in this immediate context. An echocardiogram can confirm the diagnosis and guide pericardiocentesis.*

Answer 32

Answer: Myxomatous mitral valve degeneration Explanation The correct answer is myxomatous mitral valve degeneration. This disease is the most common cardiac disease in veterinary medicine and affects up to 60% of dogs older than 8 years of age. It commonly occurs in small breed dogs and can clinically range from having only a soft murmur to being in congestive heart failure. It is caused by degeneration and accumulation of acid-staining mucopolysaccharides in the cardiac valves and most commonly affects the mitral valve. A dog with bacterial endocarditis would show signs of systemic illness such as fever and lethargy. Congenital mitral dysplasia would usually result in more marked cardiac changes (louder murmur, more regurgitation, dilated heart chambers) at a much earlier age. Systolic anterior motion or SAM of the mitral valve occurs with hypertrophic cardiomyopathy as one of the leaflets of the mitral valve obstructs the left ventricular outflow tract as the chamber contracts. The most likely cause of mitral regurgitation in this 11-year-old Shih Tzu is myxomatous mitral valve degeneration. This common cardiac disease in dogs over 8 years old, especially small breeds, ranges from a soft murmur to congestive heart failure. It involves degeneration and mucopolysaccharide accumulation in the mitral valve. Bacterial endocarditis, congenital mitral dysplasia, and systolic anterior motion are less likely due to their distinct presentations and associated symptoms.

Answer 33

Answer: Pentoxifylline Explanation Dermatomyositis (DMS) is a relatively unusual condition that results in skin lesions as well as myositis. The skin lesions initially appear as papules and vesicles which then rupture, ulcerate, and may progress to crusty alopecic lesions. The myositis sets in a little later, and atrophy of the temporalis muscle is often seen. In more severe cases, the muscles of the distal extremities become involved, and megaesophagus may be observed. Since muscle changes usually lag, other diagnostic tests such as a skin scraping and cytology are performed first to rule out other common conditions. The condition has a variable prognosis, as the clinical signs may wax and wane. Medical management usually consists of pentoxifylline, prednisone, and cyclosporine. Prednisone and cyclosporine serve as immunomodulatory medications. Pentoxifylline is used to help improve blood flow. Hycodan contains hydrocodone and is used as a cough suppressant. Meloxicam would be contraindicated in a patient on steroids. Although it looks similar to a zinc-responsive dermatosis, zinc would not be a treatment for DMS. Pentoxifylline is the recommended additional medication for treating dermatomyositis (DMS) in this 5-month-old mixed breed dog, along with immunosuppressive steroids like prednisone. DMS causes skin lesions and myositis, with symptoms such as papules, vesicles, and facial muscle atrophy. Pentoxifylline improves blood flow, aiding treatment. Hycodan (a cough suppressant), meloxicam (contraindicated with steroids), and zinc (not effective for DMS) are not suitable for this condition.

Answer 34

Answer: **Desmopressin acetate** Explanation The correct answer is *desmopressin acetate (DDAVP)*. Administration of desmopressin results in release of von Willebrand factor, which will help this patient with clotting. Given this dog's breed and elevated BMBT there is a very strong likelihood she is afflicted with von Willebrand's disease. In Dobermans this results in an inability to form a clot. This can be life threatening if the dog is taken to surgery. A whole blood transfusion does not provide an adequate source of von Willebrand factor but may be necessary if the patient's bleeding cannot be controlled despite appropriate pre-operative measures. 1,25 dihydrocholecalciferol is the active form of vitamin D which aids intestinal resorption of calcium. The BMBT does not assess factors 2, 7, 9, or 10 and therefore vitamin K is not indicated. Desmopressin acetate (DDAVP) is the appropriate treatment prior to surgery for this 1-year-old Doberman Pinscher, likely affected by von Willebrand's disease, as indicated by an elevated BMBT. DDAVP releases von Willebrand factor to aid clotting. Whole blood transfusions do not provide sufficient von Willebrand factor and are not a primary treatment. 1,25 dihydrocholecalciferol and vitamin K are not indicated, as they do not address the underlying clotting deficiency.

Answer 35

Answer: **5-9 hours** Explanation The correct answer is 5-9 hours. Neutrophil lifespans in all species, as far as we know, are less than 24 hours. Cows-16 hours; Horses- 10-11 hours. Platelets have a circulating half-life of 5-7 days and red blood cells have an approximate life span of 110 days in dogs The approximate life span of red blood cells in other species (in days) is as follows: cats-70, cow-160, horse-145, pig-86, sheep-150. *The mean circulating lifespan of a neutrophil in dogs is approximately 5-9 hours. This lifespan is consistent with other species, generally being less than 24 hours. In contrast, platelets have a half-life of 5-7 days, and red blood cells last around 110 days in dogs.*

Answer 36

Answer: Packed red blood cell transfusion, immunosuppressive doses of corticosteroids Explanation This is most compatible with a case of immune mediated hemolytic anemia (IMHA or IHA). The findings that should lead you to this diagnosis are the clinical signs of lethargy with fever, pale mucous membranes, and blood smear findings. On the blood smear, you should see that there are small numbers of erythrocytes compared to the numbers of platelets and leukocytes. You should appreciate that there is also polychromasia (variation in the color of the erythrocytes) with some red blood cells appearing very pale and others appearing a more purple color, consistent with a regenerative response from the bone marrow. It may be difficult to appreciate spherocytes on this blood smear, but this is another classic finding in cases of IMHA. IMHA can be a primary (idiopathic) condition or can be secondary to other causes including infectious diseases, autoimmune, or neoplastic conditions. Regardless, treatment consists of managing the debilitating anemia with transfusions of red blood cells and suppression of the immune mediated destruction of erythrocytes with immunosuppressive doses of steroids. Searching for an underlying cause and treating it appropriately is also critical. Plasma transfusion or whole blood transfusion with Vitamin K would be appropriate treatments for coagulopathy +/- disseminated intravascular coagulation (DIC), especially secondary to Vitamin K antagonism (i.e. rodenticide). This case should not be confused with rodenticide toxicity due to the fever and red blood cell findings on the smear. Erythropoietin and iron might be appropriate for anemia of chronic disease, especially renal disease, but are not indicated in this case. This animal's fever is not necessarily indicative of infection, as immune-mediated disease can be just as pyrogenic as an infectious process. Ampicillin is a beta lactam antibiotic but is not the critical therapy for this animal at this time. More information such as coagulation times and hematocrit would have helped you in this case and certainly would have been appropriate to run if asked or if managing this case in the real world; however, for a board exam, you may not always be given all of the information you want and must base your decision on the most likely diagnosis for the information that is provided. The most appropriate treatment for this 7-year-old Brittany Spaniel, likely diagnosed with immune-mediated hemolytic anemia (IMHA), is a packed red blood cell transfusion and immunosuppressive doses of corticosteroids. IMHA is suggested by clinical signs of lethargy, fever, pale mucous membranes, and blood smear findings, including polychromasia and a decreased erythrocyte count. Immunosuppressive therapy is crucial to manage the immune-mediated destruction of erythrocytes. Additional treatments like erythropoietin, iron, plasma transfusion, vitamin K, or antibiotics are not indicated for this condition. Further investigation into potential underlying causes is also important.

Answer 37

Answer: **Prednisone** Explanation This is a case of *lymphoma*. The cytology depicts the classic finding of a population of lymphoid cells that are predominantly lymphoblasts based on their size and characteristics. If you were unsure about their size due to magnification, there is a neutrophil in the lower left corner for comparison. The lymphoblasts are considerably larger than the neutrophil. Mature lymphocytes would be smaller than a neutrophil. Note that there is a mitotic figure in the middle of the slide. There are many treatments and protocols for lymphoma and some of the main agents known to have efficacy are prednisone, doxorubicin, cyclophosphamide, vincristine, L-asparaginase, and lomustine. There are many other efficacious chemotherapeutics for lymphoma but carboplatin is not considered a first line treatment for lymphoma in dogs. The other drugs listed are antifungal (itraconazole), antibiotic (doxycycline) and anti-parasitic (milbemycin). *Prednisone is part of the first-line therapy for lymphoma, as seen in the cytology of the fine needle aspirate showing predominantly lymphoblasts. Lymphoma treatments often include prednisone, doxorubicin, cyclophosphamide, vincristine, L-asparaginase, and lomustine. Carboplatin is not a first-line treatment for lymphoma in dogs.* The other options—doxycycline, milbemycin, and itraconazole—are not relevant for lymphoma, as they are an antibiotic, antiparasitic, and antifungal, respectively.

Answer 38

Answer: **Canine thrombopathia** Explanation The correct answer is canine thrombopathia. The disease is an autosomal recessive trait seen in Basset Hounds where platelets fail to aggregate and secrete their granules in response to normal stimuli. These dogs are at an increased risk for bleeding spontaneously, and an injury or surgical procedure could cause excessive hemorrhage. Platelet numbers and coagulation parameters are normal in this condition. It isn't an issue with platelet number, but of function. Rodenticide would cause elevated clotting times. Immune-mediated thrombocytopenia would cause a low platelet count. A nasal foreign body would be less likely to cause a bilateral bleed and would not attribute to the ecchymotic hemorrhages noted on the abdominal skin. *The top differential for the 1-year-old Basset Hound with epistaxis and ecchymotic hemorrhages is canine thrombopathia. This autosomal recessive trait in Basset Hounds results in platelets failing to aggregate and secrete granules normally, leading to increased bleeding risk despite normal platelet numbers and coagulation parameters. Rodenticide toxicity would elevate clotting times, immune-mediated thrombocytopenia would lower platelet count, and a nasal foreign body typically wouldn't cause bilateral bleeding or ecchymotic hemorrhages.*

Answer 39

Answer: **Hemolysis** Explanation The correct answer is *hemolysis*. Zinc causes a Heinz body anemia and hemolysis.

Answer 40

Answer: **Type II** Type I (aka immediate) hypersensitivity reactions occur when re-exposure of an antigen results in an allergic reaction. The antigen is presented and causes B cell production of IgE antibodies. Type Il (aka cytotoxic) occurs when an antigen on a cell surface binds with an antibody and is then recognized by the body as being foreign. The antigen on the cell may have been a normal feature of the cell or it may have been acquired, such as a drug binding to the cell. Macrophages or dendritic cells then recognize the cell and "present the antigen" which then causes B cell proliferation and production of IgG and IgM antibodies. The antibodies bind to the cell and activate the complement cascade which results in cell lysis/destruction. Type Ill (aka immune complex) occurs when there are more antigens than there are antibodies. The antigens float around in the circulation and multiple antigens may bind one antibody, thus forming an immune complex. Large complexes can be cleared by macrophages, but smaller ones may evade the macrophages. Type IV (delayed type hypersensitivity) takes several days to occur and rather than being antibody-mediated, it is actually cell-mediated. Cytotoxic CD8+ T cells and CD4+ helper T cells recognize antigen that is in a complex with major histocompatibility complex 1 or 2. This results in proliferation and activation of the cells. Activated CD8+ T cells then destroy the antigen containing cells while activated macrophages release hydrolytic enzymes. *Immune-mediated hemolytic anemia (IMHA) is associated with a Type II hypersensitivity reaction. In Type II hypersensitivity, antibodies target antigens on cell surfaces, leading to cell destruction. This can occur due to the immune system mistakenly recognizing normal cell surface antigens or acquired antigens, such as those from drug interactions, as foreign. The process involves macrophages or dendritic cells presenting the antigen, leading to B cell production of IgG and IgM antibodies, which activate the complement cascade, resulting in cell lysis. This contrasts with other hypersensitivity types that involve different immune mechanisms.*

Answer 41

Answer: Immune mediated hemolytic anemia Explanation In immune mediated hemolytic anemia red blood cells are coated with immunoglobulins and are then engulfed by macrophages. As a result, the RBC will lose a portion of its cell membrane but not hemoglobin. With the loss of part of the cell membrane, spherocytes appear smaller (without volume loss), no central pallor, and stain deeply red. In iron deficiency, RBC will be hypochromic (less red) and smaller (microcytic) due to less volume. Cobalamin and folate are necessary for DNA synthesis. Giant schnauzers have an inherited cobalamin malabsorption which results in macrocytes and ovalocytes in circulation. Grape and raisin toxicity result in acute renal failure. Spherocytes are consistent with immune-mediated hemolytic anemia (IMHA). In IMHA, red blood cells are coated with immunoglobulins and partially phagocytized by macrophages, leading to a loss of cell membrane but not hemoglobin. This results in smaller, deeply red cells without central pallor. In iron deficiency, red blood cells are hypochromic and microcytic. Cobalamin and folate deficiencies lead to macrocytes and ovalocytes, and grape and raisin toxicity cause acute renal failure, not changes in red blood cell morphology.

Answer 42

Answer: Azathioprine Explanation The mainstays of therapy are immunosuppression with corticosteroids and other drugs such as azathioprine or cyclosporine. Transfusions with whole blood, packed red blood cells, or oxyglobin may be necessary. Piroxicam is a non-steroidal anti-inflammatory and is contraindicated in any patient receiving corticosteroids due to risk of cumulative GI toxicity. Enrofloxacin is an antibiotic and would not commonly be prescribed for autoimmune disease. Maropitant (Cerenia) is used to treat nausea and vomiting. Azathioprine is used for treating immune-mediated hemolytic anemia (IMHA) in dogs, often alongside corticosteroids for immunosuppression. Other options include cyclosporine and blood transfusions if needed. Piroxicam, a non-steroidal anti-inflammatory, is contraindicated with corticosteroids due to GI toxicity risk. Enrofloxacin is an antibiotic, and Maropitant (Cerenia) is used for nausea and vomiting, not for IMHA.

Answer 43

Answer: Doxycycline Explanation Doxycycline can result in delayed bone growth and discoloration of the teeth in young growing animals and is thus contraindicated. The other medications listed do not have a direct effect on young growing animals and are safe to administer; however, one must consider the likely pathogen present in the wound, what type of susceptibility pattern it has, as well as the likely penetration of your antibiotic into the area where you want it to exert its effect prior to making a choice.

Answer 44

Answer: Staphylococcus Explanation Bacteria may be a cause of folliculitis. Pustules such as this are commonly associated with Staphylococcus. Dermatophytes, and most species of Demodex, can also infect the hair follicle. Sarcoptes scabiei, which is a non-seasonal, intensely pruritic, transmissible mite, affects the stratum corneum and is less likely to cause a folliculitis. Chyletiella mites feed on the keratin layer of the skin as well and are less likely to cause folliculitis. These mites are known as "walking dandruff" and may cause skin flaking and typically intense pruritis. Trichodectes is a chewing louse, which chews the skin but does not involve the hair follicle.

Answer 45

Answer: Bacterial pyoderma The lesions in the image are pustules, which form with neutrophilic inflammation and are accumulations of dead or dying polymorphonuclear leukocytes. Pustules are seen with differing types of dermatitis ranging from bacterial pyoderma, demodicosis, allergic reaction, and pemphigus. Determining the primary etiology will aid in proper treatment and resolution. Diagnostics that are always appropriate for diagnosing skin infections include skin scraping, impression smears, hair plucking for fungal culture, and biopsies if the preliminary diagnostics are unrewarding. Demodicosis is the only mite infection that has been known to cause pustules or papules. Sarcoptes and Cheyletiella are not known to cause pustules. Sarcoptes is also usually associated with intense pruritis. Dermatophytosis can cause pustules, but this is not routinely seen, which makes bacterial pyoderma the top differential from the given answer choices.

Answer 46

Answer: Burn off Explanation Burning may cause the ticks to become agitated and regurgitate their stomach contents into the surrounding tissues they are feeding from. This will cause severe inflammation and pruritis, and can also lead to tick borne diseases. Burning can also harm the patient. The correct way to remove ticks is to grasp them with forceps just behind their heads and gently apply traction until they release. Twisting will cause the heads to stay lodged under the skin. For large numbers or ticks, as seen in this image, Fipronil pour-ons and Permethin topicals can be used to kill off the ticks. Periodic pour-ons and bathing routinely can also be used in the face of severe infestations.

Answer 47

Answer: The disease is familial, and is often cyclic and will regress. Explanation Familial dermatomyositis is a familial disease seen in Collies, Shetland sheepdogs, and other collie breeds. Diagnosis can be made with skin or muscle biopsies, but can be difficult as the clinical and histopathologic signs can wax and wane. Inciting causes can include vaccinations, sunlight, viral infections, or drugs. Some cases; however, will come and go without obvious inciting causes. Some cases can become severe enough to include muscle atrophy; megaesophagus has also been seen with this disease. Treatments are often symptomatic and supportive and include Vitamin E supplements, Omega 3 fish oils, treatments for any secondary bacterial infections, and pentoxifylline. Prednisone can also be used to get more severe cases under control. Avoiding prolonged sun exposure can also help. Educating the owner on the fact that signs will reoccur despite treatment can alleviate some owner frustrations. Often times signs will regress with or without treatments. Educate owners on neutering animals to prevent propagation of diseased animals.

Answer 48

Answer: Benign Neglect Explanation Histiocytomas are typically benign and will often present as a small, raised mass that may or may not be ulcerated. Fortunately, these masses usually regress on their own, and surgical or medical intervention is typically not necessary. The most reasonable treatment option for a histiocytoma in a 2-year-old Dachshund is benign neglect. Histiocytomas are usually benign and often regress on their own without the need for surgical or medical intervention. They typically present as small, raised masses that may be ulcerated but usually resolve spontaneously.

Answer 49

Answer: Depigmentation of the nasal planum Explanation The correct answer is depigmentation of the nasal planum. Clinical signs consistent with DLE include depigmentation, erythema, scaling, and loss of the "cobblestone" appearance of the nasal planum. Alopecia, crusting, scaling, and ulcerations can also be seen on the face, muzzle, lips, pinnae, and periorbitally. Truncal alopecia would be more common with endocrine disease, such as hypothyroidism or Cushing's disease. Discoid lupus is the cutaneous form, and the joints are not affected like they are with systemic lupus erythematosus (SLE).

Answer 50

Answer: Clindamycin Explanation Since you are suspicious of methicillin resistance, using any cephalosporins such as Convenia or Simplicef would not be useful. Trimethoprim-sulfa will probably be effective; however, this antibiotic should be avoided in Dobermans as they are prone to side effects such as anemia, thrombocytopenia, arthritis, and renal toxicity. These side effects are due to a type-three hypersensitivity. Chloramphenicol may also be effective against the infection, but clindamycin would be a better choice, as it has fewer side effects. Chloramphenicol can cause peripheral neuropathy, gastrointestinal upset, bone marrow suppression, and hepatotoxicity. Additionally, chloramphenicol can also cause aplastic anemia in humans. Clindamycin can also cause gastrointestinal upset but seems to be better tolerated than chloramphenicol.

Answer 51

Answer: Discoid lupus erythematosus Explanation Discoid lupus (along with Pemphigus foliaceus) are autoimmune conditions that can result in ulcerative nasal dermatitis and loss of cobblestone appearance. Dermatophytosis (ringworm) often affects the muzzle. However, it rarely affects the nasal planum, because dermatophytes live in hair follicles and there are no hair follicles on the nasal planum. (This is also why it would not be folliculitis). Zinc-responsive dermatosis typically causes scaling and crusting but not usually erosions or ulcers. The next step for this dog would be to biopsy.

Answer 52

Answer: Skin scrape Explanation Demodex injai typically causes greasy seborrhea, especially on the face and dorsal trunk. Terriers and Shih Tzus may be predisposed. Some dogs may be pruritic. This mite is long and slender when compared with Demodex canis. A diet trial and intradermal skin test may be indicated in the future if the skin scrape is negative. A bacterial culture may be needed if bacteria were seen on cytology. There is no indication to perform a CBC. None of the other tests would be considered part of a dermatological database.

Answer 53

Blastomycosis (Blastomyces dermatiditis) Explanation The correct answer is blastomycosis. These findings are most consistent with blastomycosis. Lymphoma would be a great differential but is less consistent with the nodular lung pattern and suppurative inflammation in the lymph node. Plague is an interesting differential for the lymphadenopathy and cytology findings but is not consistent with the lung pattern or history. This Weimaraner's disease is too severe to be explained by kennel cough alone. While this diagnosis is sometimes made easy by visualization of organisms in aspirates or skin scrapings, it is not always seen as in this case. Remember, Blastomyces is seen as a broad-based budding yeast. The next step to obtain a definitive diagnosis in this patient would be a transtracheal wash or bronchoalveolar lavage.

Answer 54

Answer: 800 kcal/day Explanation The correct answer is 800 kcal/day. There are many formulas for calculating RER and they all should work out to be pretty close to this. The formula used here is body weight (kg) to the 0.75 power times 70. (70 * BW^0.75). Another formula that has been recommended for this calculation is (30 * BW + 70). Note that the results will be different compared to the (70 * BW^0.75) formula but they both should get you close enough to the correct answer. You will have access to an "on screen" calculator during the exam if necessary, but may want to remember multiple ways to do a calculation should there not be access to a "power" (^) function.

Answer 55

Answer: Grippotyphosa, pomona, bratislava Explanation The correct answer is grippotyphosa, pomona, and bratislava. Icterhemorrhagiae and canicola were the most common serovars isolated in the past. The leptospires penetrate mucous membranes or abraded skin and multiply in the blood stream and spread to organs. The antibody response usually limits the response to the renal tubular epithelial cells. Clinical signs include anorexia, pyrexia, vomiting, dehydration, PU/PD, anuria or oliguria. The standard diagnostic test is the microscopic agglutination test (MAT); be careful when interpreting titers. Remember, leptospirosis is zoonotic.

Answer 56

Answer: Morphine and thiopental Explanation In this case, thiopental is contraindicated because the patient is a sighthound. Thiopental is an ultra-short acting barbiturate. Recovery depends on redistribution to tissues, including fat. Because sighthounds have very little fat, they have prolonged recoveries and greater complications with these drugs. Morphine is contraindicated in this patient due to the ulcerating mast cell tumor. Morphine can cause histamine release and should be avoided in mast cell tumor patients.

Answer 57

Answer: 90 ml/kg Explanation The isotonic crystalloids shock dose in dogs is 90 ml/kg. 1/4 to 1/3 of this volume should be administered initially and the patient reassessed. In cats, the isotonic crystalloids shock dose is 40-60 ml/kg. Synthetic colloids can be administered at a dose of 10-20 ml/kg in dogs and 5-10 ml/kg in cats and hypertonic saline at a dose of 5 ml/kg.

Answer 58

Answer: Tetracycline antibiotics Explanation The correct answer is tetracycline antibiotics. The causative agent for the dog's clinical signs is Neorickettsia helminthoeca. Treatment of choice for this rickettsial agent is tetracycline antibiotics. The fluke itself is not responsible for the clinical signs, but may be treated effectively with Praziquantel.

Answer 59

Answer: ONCEPT vaccine！ Explanation The image shows a lymph node with metastatic melanoma (the large cell with black melanin pigment). The ONCEPT vaccine, also commonly referred to as the "melanoma vaccine" was given a conditional product license in 2007 and was USDA approved in 2010 as a therapeutic vaccine for cancer treatment. Palladia is a receptor tyrosine kinase inhibitor approved for use in mast cell tumors in dogs. Doxorubicin, vincristine and mitoxantrone are human chemotherapy drugs commonly used off-label in veterinary oncology but not routinely for melanoma.

Answer 60

Answer: Amputation and treatment with an antifungal Pythium is an aquatic organism that inhabits ponds of the Southeast United States. These organisms have different cell walls than regular fungi, which makes them difficult to treat since most antifungal treatments target fungal cell wall synthesis. Prognosis is extremely poor with this disease and amputation (if the lesions are localized to an affected limb) is currently the best option. Amputation should always be followed with multiple long-term antifungal therapies. Owners should be warned that local postoperative recurrence is common. Dogs are most commonly affected, but this disease can also occur in cats. It has also been reported in humans and horses. Doxycyline is an antibiotic and would not be effective for this disease. Prednisone would be contraindicated for pythium. Lufenuron is a chitin synthesis inhibitor used for flea control and would not be effective. Ivermectin is an anti-parasite drug and would not be effective.

Answer 61

Answer: Blastomycosis (Blastomyces dermatiditis) Explanation The correct answer is blastomycosis. These findings are most consistent with blastomycosis. Lymphoma would be a great differential but is less consistent with the nodular lung pattern and suppurative inflammation in the lymph node. Plague is an interesting differential for the lymphadenopathy and cytology findings but is not consistent with the lung pattern or history. This Weimaraner's disease is too severe to be explained by kennel cough alone. While this diagnosis is sometimes made easy by visualization of organisms in aspirates or skin scrapings, it is not always seen as in this case. Remember, Blastomyces is seen as a broad-based budding yeast. The next step to obtain a definitive diagnosis in this patient would be a transtracheal wash or bronchoalveolar lavage.

Answer 62

Answer: Decreased gastrointestinal tone and motility Explanation Atropine is an anticholinergic, often used during premedication and intraoperatively to increase heart rate. It causes a decrease in tear secretion, salivary secretion, and Gl tone and motility. Atropine reduces the influence of the vagus nerve on the heart but does not block it completely. Lidocaine is used to treat VPCs.

Answer 63

Answer: **Hypesenstvty reaction** Explanation The correct answer is *hypersensitivity reaction*. Doberman Pinschers are more susceptible to hypersensitivity reactions from sulfa drugs as compared to other breeds. Type Ill reactions can result in immune complex disease which can cause arthritis, nephritis, and uveitis. Other possible side effects from this class of antibiotics that are not specific to the Doberman include KCS, hepatitis, and blood dyscrasias.

Answer 64

Answer: Metaphisis Explanation The correct answer is the metaphysis. Hypertrophic osteodystrophy (HOD) is a condition seen in young, growing large breed dogs. It affects the metaphyses of all long bones and appears as an abnormal radiolucent line within the metaphysis. The disease is usually self-limiting but can cause limb deformities or systemic illness. The etiology is unknown but may be correlated with Ca/P levels and balance, vitamin C deficiency, and certain diseases including distemper.

Answer 65

Answer: Urine culture The diagnosis you should have in mind is discospondylitis. Be sure not to confuse this with spondylosis, which is typically not clinically significant and can be expected in most older dogs. The radiographic description is relatively specific for this condition. Neoplasia in the spine should be lower on your differential list because it typically does not cross joints. Disc herniation cannot be ruled out, and advanced imaging would be necessary to know for certain, but given the exam and radiographic findings, discospondylitis should be your top differential. Discospondylitis is usually bacterial in origin, with Staphylococcus being the most common organism involved. Other organisms identified include Brucella canis, E. coli, Pasteurella, Aspergillus, and Streptococcus. In an attempt to identify the causative agent, urine and blood cultures should be considered. The other answer choices are not as high yield in identifying the specific bacterial cause or underlying etiology.

Answer 66

Answer: Temporalis The mass depicted in this three dimensional CT reconstruction involves the coronoid process. The ramus of the mandible consists of three distinct processes, the most dorsal being the coronoid process. It projects into the temporal fossa and provides an area for attachment of the temporalis muscle. The condylar (or condyloid) process is just ventral and slightly caudal to the coronoid process. This process is a point of articulation between the maxilla (retroarticular process) and mandible. Disruption of this region will result in temporomandibular joint luxation. The most ventral process is the angular process. This structure provides an area for attachment of the digastricus muscle. The masseter muscle inserts laterally on the mandible, while the pterygoid muscle inserts medially. The masseter, pterygoid, and temporalis muscles function to close the mouth while the digastricus opens the mouth.

Answer 67

Answer: Corrective osteotomy Explanation The correct answer is corrective osteotomy. Corrective osteotomies of the radius and ulna are often performed to relieve pain and the functional abnormalities induced by angular limb deformities.

Answer 68

Answer: Euthanize immediately and submit for testing or vaccinate immediately and quarantine for 4 months. Explanation Per the 2016 Rabies Guidelines: Since the dog is unvaccinated, it should either be euthanized and tissue submitted for rabies testing OR immediately vaccinated for rabies and quarantined for 4 months. The Direct Fluorescent Antibody Test detects viral antigens and should be tested on two locations from the brain (brainstem and cerebellum) and is the test of choice for rabies diagnosis. If the dog was current on rabies vaccination, the guidelines direct to booster the rabies vaccination immediately and have the owners observe closely for 45 days. If owners are able to provide proof the dog had been previously vaccinated for rabies but is overdue: guidelines direct to booster rabies vaccination immediately and keep the dog under owner observation for 45 days.

Answer 69

Answer: Physicaly punishingl Explanation Owners physically punishing their dogs in an attempt to change the dog's behavior is a common welfare concern.

Answer 70

Answer: Baylisascaris Explanation The correct answer is Baylisascaris. Baylisascaris procyonis is an ascarid parasite of raccoons that causes mild signs in raccoons but can undergo aberrant migration in humans and cause fatal central nervous system signs. Baylisascaris Infection (Raccoon Roundworm): Comprehensive Veterinary Guide Definition: Baylisascaris infection, also known as raccoon roundworm infection, is caused by the nematode Baylisascaris procyonis. It primarily infects raccoons but can also affect humans and other animals, including dogs. Pathophysiology: • Infection Mechanism: Humans and animals become infected by ingesting embryonated eggs from contaminated soil, water, or objects. • Larval Migration: Ingested larvae migrate through tissues, causing damage depending on the site of invasion, such as the brain (neural larva migrans), eyes (ocular larva migrans), or other organs (visceral larva migrans). Causes: • Primary Host: Raccoons are the primary host, shedding eggs in their feces. • Transmission: Eggs become infectious in the environment after 2-4 weeks. Human infection usually occurs through accidental ingestion of contaminated material. Symptoms: • General: Nausea, tiredness, liver enlargement. • Neurological: Loss of coordination, muscle control, and attention; potential for blindness or coma if the brain is affected. Clinical Changes: • Infected individuals may exhibit neurological symptoms or damage to other organs, depending on larval migration pathways. Diagnosis: • Challenges: Diagnosis is difficult due to the rarity of infection and nonspecific symptoms. It is often made by exclusion of other diseases. • Testing: No widely available tests; diagnosis may rely on patient history and clinical signs. Treatment: • Medications: Albendazole, a broad-spectrum anthelmintic, is recommended, though not completely effective. Early treatment can help reduce severe damage. • Supportive Care: Symptomatic treatment based on the affected organs. Prevention: • Environmental Management: Prompt removal of raccoon feces, avoiding contact with raccoons, and hygiene practices like handwashing can reduce the risk of infection.

Answer 71

Answer: Type I HPS, IgE Atopic dermatitis is mediated primarly by IgE and is considered a Type I, or immediate, hypersensitivity reaction. In some species, IgG may also play a role. It is interesting to note that not all atopic patients present with a typical Type 1 hypersensitivity. Some patients with atopic dermatitis do not have measurable IgE against environmental allergens. This syndrome is termed "atopic-like."

Answer 72

Answer: **Start aggressive IV fluid therapy and run a chemistry panel** The correct answer is start aggressive IV fluid therapy and run a chemistry panel. Addisonian patients often present in hypovolemic shock, so the first step to treating this dog is to restore vascular volume with IV fluids and to run a chemistry panel to check the extent of electrolyte abnormalities (hyponatremia, hyperkalemia, and elevated BUN). IV dexamethasone would not take precedence over restoring vascular volume, and subcutaneous fluid treatment is not aggressive enough for treatment of hypovolemia. Abdominal ultrasound would not be a priority in this case but could eventually be helpful in ruling in/out other differentials. Lysodren is used for treating hyperadrenocorticism. One possible complication of Lysodren treatment is to make a dog Addisonian, which often causes the animal to present with the signs described as in the question.

Answer 73

Answer: Surgical replacement will be curative. Consider not breeding. Prolapsed glands of the third eye lid ("cherry eye") are congenital defects and will likely be passed on to future generations. Repair is straight forward with prolapsed gland replacement and tacking to periorbital rim (Kaswan anchoring technique) or using the Morgan pocket technique. Surgical removal is NOT recommend as you will remove the tear gland and predispose to iatrogenic keratoconjunctivits sicca.

Answer 74

Answer: Blood glucose=45 mg/dl, Serum insulin-high Explanation The correct answer is blood glucose-45 mg/dl, serum insulin-high. An insulinoma can result in an animal having normal to high insulin levels in the face of low blood glucose levels because the normal controls of insulin secretion are lost. **Comprehensive NAVLE Preparation: Insulinoma in Dogs** Definitions & Pathophysiology: • Insulinoma: A rare, malignant, functional pancreatic β-cell tumor in dogs, secreting insulin independent of blood glucose levels. This results in persistent hypoglycemia and its associated clinical signs. • Pathophysiology: The neoplastic β-cells lose their ability to regulate insulin secretion in response to hypoglycemia. This unregulated insulin release decreases blood glucose levels, leading to neuroglycopenic and adrenergic effects. Causes: • Insulinomas are malignant and often metastasize to lymph nodes and the liver. The exact cause is unknown, but it is most common in middle-aged to older dogs, with no specific sex predilection. Breeds like Golden Retrievers, Labrador Retrievers, and Boxers are overrepresented. Clinical Signs: • Early Signs: Episodic weakness, lethargy, ataxia, collapse, and seizures. These signs are often precipitated by fasting, exercise, or excitement. • Advanced Signs: Prolonged or severe hypoglycemia can result in coma or death. Peripheral polyneuropathy may also occur, leading to muscle atrophy, paresis, and decreased reflexes. Diagnosis: • Whipple’s Triad: (1) Documented hypoglycemia (<70 mg/dL), (2) Clinical signs consistent with hypoglycemia, (3) Resolution of signs after glucose administration. • Laboratory Findings: Persistent hypoglycemia with inappropriate normal to high insulin levels. • Advanced Imaging: Abdominal ultrasound, CT, and MRI are used to identify pancreatic masses. Somatostatin receptor scintigraphy (SRS) may detect metastases. Differential Diagnosis: • Other causes of hypoglycemia include hypoadrenocorticism, hepatic insufficiency, sepsis, and iatrogenic causes like insulin overdose. Treatment: • Surgical Management: Partial pancreatectomy to remove the primary tumor and resect metastases when possible. Surgical removal improves survival times significantly but is rarely curative due to the high rate of metastasis. • Medical Management: • Dietary: Frequent meals high in protein, fats, and complex carbohydrates to minimize insulin secretion. • Medications: • Prednisone (0.5 mg/kg/day): Increases blood glucose by promoting gluconeogenesis and glycogenolysis. • Diazoxide (5 mg/kg PO q12h): Inhibits insulin release, promotes glycogenolysis, and decreases cellular glucose uptake. • Octreotide (2-4 μg/kg SC q8-12h): A somatostatin analog that inhibits insulin secretion. • Glucagon (CRI 5 ng/kg/min): Used in refractory hypoglycemia to maintain euglycemia. • Streptozocin (500 mg/m² IV q3 weeks with diuresis): Chemotherapeutic agent targeting pancreatic β-cells, used in cases with metastasis. Prognosis: • Surgical Resection: Median survival time is 12-14 months post-surgery, with survival rates higher in dogs without metastasis. • Medical Management Alone: Median survival time is around 6 months. However, combining surgery and medical therapy can extend survival to 2-3 years. Important Points for NAVLE: • Recognize clinical signs associated with hypoglycemia and the significance of Whipple’s Triad in diagnosis. • Understand the role of advanced imaging and laboratory diagnostics in identifying insulinomas. • Familiarize yourself with both surgical and medical management strategies, emphasizing the importance of managing hypoglycemia and the potential for metastasis. • Be aware of the drugs used in managing insulinoma and their mechanisms, including glucocorticoids, diazoxide, and somatostatin analogs, as well as the use of chemotherapeutic agents in metastatic cases.

Answer 75

Answer: ACTH low, cortisol high Explanation The correct answer is ACTH low, cortisol high. Prednisone is a synthetic corticosteroid that cross reacts with assays measuring endogenous cortisol levels, causing an artificially elevated cortisol measurement on blood tests. The feedback mechanism on the pituitary gland inhibits ACTH production, making it low. ACTH low, cortisol high is expected in a dog with iatrogenic Cushing’s disease from high-dose prednisone. Prednisone, a synthetic corticosteroid, cross-reacts with cortisol assays, resulting in artificially elevated cortisol levels. The negative feedback on the pituitary gland suppresses ACTH production, leading to low ACTH levels.

Answer 76

Answer: High-dose dexamethasone suppression test Explanation The correct answer is high-dose dexamethasone suppression test. HDDST will suppress cortisol secretion in about 75% of PDH patients 3-6 hours post dexamethasone administration. Cortisol secretion does not become suppressed with dexamethasone administration with adrenal dependent hyperadrenocorticism. If cortisol secretion is suppressed with a HDDST, PDH is diagnosed. If cortisol is not suppressed, there is a 50-50 chance that the hyperadrenocorticism is due to PDH or an adrenal tumor. LDDST will suppress cortisol secretion in approximately 65% of pituitary dependent hyperadrenocorticism patients. The urine cortisol:creatinine ratio measures the significance of urine cortisol concentration and may be increased with both PDH and ADH. Serum cortisol levels may be affected in many different situations such as stress; therefore they are an unreliable indicator of disease. An elevated serum cortisol level will not differentiate between PDH and ADH. High-dose dexamethasone suppression test (HDDST) is the best diagnostic test to differentiate pituitary-dependent hyperadrenocorticism (PDH) from adrenal-dependent hyperadrenocorticism (ADH) in dogs. In about 75% of PDH cases, cortisol secretion is suppressed 3-6 hours post-dexamethasone administration, confirming PDH. In contrast, cortisol secretion remains unsuppressed in ADH. If suppression occurs, PDH is diagnosed. If not, the hyperadrenocorticism could be either PDH or an adrenal tumor, with a 50-50 chance. Other tests, like LDDST, urine cortisol: creatinine ratio, and serum cortisol levels, are less reliable for distinguishing between PDH and ADH.

Answer 77

Answer: Start aggressive IV fluid therapy and run a chemistry panel Explanation The correct answer is start aggressive IV fluid therapy and run a chemistry panel. Addisonian patients often present in hypovolemic shock, so the first step to treating this dog is to restore vascular volume with IV fluids and to run a chemistry panel to check the extent of electrolyte abnormalities (hyponatremia, hyperkalemia, and elevated BUN). IV dexamethasone would not take precedence over restoring vascular volume, and subcutaneous fluid treatment is not aggressive enough for treatment of hypovolemia. Abdominal ultrasound would not be a priority in this case but could eventually be helpful in ruling in/out other differentials. Lysodren is used for treating hyperadrenocorticism. One possible complication of Lysodren treatment is to make a dog Addisonian, which often causes the animal to present with the signs described as in the question. Start aggressive IV fluid therapy and run a chemistry panel for a dog suspected of having Addison’s disease. Addisonian patients often present in hypovolemic shock, so restoring vascular volume with IV fluids is the top priority. The chemistry panel will help assess electrolyte imbalances, such as hyponatremia, hyperkalemia, and elevated BUN. IV dexamethasone and subcutaneous fluids are insufficient for treating hypovolemia, and abdominal ultrasound, while useful later, is not a priority. Lysodren is for hyperadrenocorticism treatment and not appropriate here.

Answer 78

Answer: Dexamethasone Explanation The correct answer is dexamethasone. Administration of dexamethasone or desoxycorticosterone acetate (DOCA) prior to ACTH stimulation test does not confound the test results. Administration of prednisone, cortisone, prednisolone, and flucortisone acetate would show false elevations in test results. Dexamethasone administration would not adversely affect the results of an ACTH stimulation test. Unlike prednisone, cortisone, prednisolone, and flucortisone acetate, which can cause false elevations, dexamethasone and desoxycorticosterone acetate (DOCA) do not interfere with the test, making them safe to use before the ACTH stimulation test.

Answer 79

Answer: **Regular** Explanation Listed from shortest acting and most potent to longest acting and least potent: Regular, NPH, Lente, PZI, Ultralente. The treatment of DKA involves IV fluids and regular insulin, given either by CRI or the intermittent IM dosing technique. Regular insulin is continued until the patient is eating well and is hydrated, and can be switched to a longer-acting insulin, to be given SQ at home. *Regular insulin is the best choice for treating diabetic ketoacidosis (DKA) in this case. Regular insulin is the shortest acting and most potent, ideal for managing DKA. Treatment involves IV fluids and regular insulin, administered via continuous rate infusion (CRI) or intermittent IM dosing. Once the patient stabilizes, eating well, and hydrated, they can be transitioned to a longer-acting insulin for home use.* **Comprehensive NAVLE Study Guide: Diabetic Ketoacidosis (DKA) in Small Animals** Definitions and Etiology • Diabetic Ketoacidosis (DKA): A life-threatening complication of diabetes mellitus characterized by hyperglycemia, ketonemia, and metabolic acidosis. • Causes: DKA occurs due to absolute or relative insulin deficiency, often precipitated by concurrent illness, such as infection, pancreatitis, or neoplasia. Pathophysiology • Insulin Deficiency: Leads to hyperglycemia due to increased gluconeogenesis, glycogenolysis, and decreased glucose utilization. • Ketogenesis: In the absence of insulin, free fatty acids are converted into ketones in the liver. Accumulation of ketones (e.g., β-hydroxybutyrate, acetoacetate) results in metabolic acidosis. • Counterregulatory Hormones: Glucagon, cortisol, epinephrine, and growth hormone exacerbate hyperglycemia and ketogenesis by promoting lipolysis and gluconeogenesis. • Electrolyte and Acid-Base Disturbances: Significant fluid and electrolyte losses occur due to osmotic diuresis, leading to dehydration, hypokalemia, and metabolic acidosis. Clinical Signs • History: Polyuria, polydipsia, weight loss, and acute symptoms like vomiting, diarrhea, anorexia, lethargy, and dehydration. • Physical Examination: Tachycardia, weak pulses, poor skin turgor, dry mucous membranes, Kussmaul respirations (deep and labored breathing), and possible neurologic signs like weakness or altered mentation. Diagnosis • Laboratory Tests: • Blood Glucose: Marked hyperglycemia (>300 mg/dL). • Ketones: Detected in blood and urine (β-hydroxybutyrate being the primary ketone in blood). • Electrolytes: Hyponatremia, hypokalemia, and hypophosphatemia common. • Acid-Base Status: Metabolic acidosis (pH < 7.3, bicarbonate < 15 mEq/L). • Serum Osmolality: Increased, especially in cases of hyperglycemic hyperosmolar syndrome (HHS). Treatment • Fluid Therapy: • Rehydration: Critical initial step; typically with isotonic crystalloids (e.g., 0.9% NaCl). Adjustments may be needed based on electrolyte status. • Monitoring: Frequent reassessment of hydration status, electrolytes, and acid-base balance. • Insulin Therapy: • Regular Insulin: Administered initially as a low-dose continuous rate infusion (CRI) or intermittent intramuscular injections. • Glucose Monitoring: Target glucose reduction of 50-75 mg/dL per hour; once glucose <250-300 mg/dL, add dextrose to fluids to prevent hypoglycemia while continuing insulin to resolve ketonemia. • Electrolyte Management: • Potassium: Replacement essential as insulin therapy shifts potassium intracellularly. Monitoring is crucial to avoid life-threatening hypokalemia. • Phosphorus: Monitor and replace if hypophosphatemia is severe, as it may lead to hemolysis and weakness. • Bicarbonate: Generally not recommended unless severe acidosis (pH < 7) persists after fluid therapy. • Addressing Concurrent Illnesses: Identifying and treating underlying causes such as infections, pancreatitis, or other comorbidities is essential for successful management. Complications • Cerebral Edema: Rare but severe complication, particularly in overzealous fluid or insulin therapy. It necessitates careful monitoring and gradual correction of hyperglycemia and electrolyte imbalances. • Hypoglycemia: Can occur if insulin therapy is not carefully titrated. Prognosis • Mortality: Depends on the severity of the initial presentation and the presence of concurrent diseases. Mortality rates for DKA range from 20-30%, with worse outcomes in cases complicated by HHS.

Answer 80

Answer: **Correction of acidosis, electrolyte abnormalities, and hyperosmolality** Explanation The correct answer is correction of acidosis, electrolyte abnormalities, and hyperosmolality. Initial treatment of DKA patients is aimed at correcting acidosis by administering bicarbonate (if the total bicarbonate is markedly low), correcting electrolyte abnormalities with IV fluids, potassium and phosphorus supplementation, and correction of hyperosmolality. Regulating blood glucose, getting the animal to eat, controlling obesity and concurrent disease should be addressed after immediate life-threatening issues are resolved. *Correction of acidosis, electrolyte abnormalities, and hyperosmolality is the primary goal in the initial treatment of diabetic ketoacidotic (DKA) dogs. Treatment involves administering bicarbonate for severe acidosis, correcting electrolyte imbalances with IV fluids, potassium, and phosphorus supplementation, and addressing hyperosmolality. Once these life-threatening issues are managed, focus can shift to regulating blood glucose, encouraging eating, and addressing obesity or concurrent disorders.*

Answer 81

Answer: **Catecholamines** Explanation A pheochromocytoma is a tumor of the adrenal medulla. To review, the adrenal gland is composed of the adrenal cortex (outer layer) which is divided into the zona glomerulosa, zona fasciculata, and zona reticularis. The zona glomerulosa is the main site of aldosterone production. The zona fasciculata produces glucocorticoids (mainly cortisol). The zona reticularis is the site of androgen production. The adrenal medulla is the inner part of the adrenal gland and consists of chromaffin cells. These cells are responsible for making catecholamines (epinephrine and norepinephrine). *Catecholamines are secreted by pheochromocytomas, which are tumors of the adrenal medulla. The adrenal gland consists of the adrenal cortex and adrenal medulla. The adrenal medulla, composed of chromaffin cells, produces catecholamines like epinephrine and norepinephrine. These hormones are responsible for the hypertension, tachyarrhythmias, seizures, and collapse seen in affected dogs. Other substances like aldosterone, cortisol, calcium, and estrogen are produced in different parts of the adrenal gland but are not associated with pheochromocytomas.* **Comprehensive NAVLE Study Guide: Pheochromocytoma in Dogs** Definition and Etiology • Pheochromocytoma: A catecholamine-producing tumor that originates from the adrenal medulla or, less commonly, extra-adrenal chromaffin tissue. • Causative Agent: Tumors derived from chromaffin cells that secrete excessive catecholamines, mainly norepinephrine, and epinephrine. • Pathogenesis: Tumors cause excessive and unpredictable catecholamine release, leading to variable clinical signs. These tumors can be slow-growing but often malignant, with a potential for local invasion and metastasis. Clinical Signs • Signs of Catecholamine Excess: Tachycardia, hypertension, tachypnea, panting, cardiac arrhythmias, and episodic collapse. • Nonspecific Signs: Anorexia, weight loss, lethargy, and episodic weakness. • Neurological Signs: Anxiety, muscle tremors, pacing, and seizures. • Signs from Tumor Size/Invasiveness: Abdominal distension, ascites, hind-limb edema, and potential retroperitoneal hemorrhage from tumor rupture. Diagnosis • Clinical Suspicion: Based on clinical signs and detection of an adrenal mass via ultrasonography. • Urine Normetanephrine:Creatinine Ratio: Elevated levels suggest pheochromocytoma. • Imaging: Abdominal ultrasonography, CT, and MRI for tumor localization and assessing invasiveness. • Blood Pressure Measurement: Persistent hypertension is a hallmark but is only present in ~50% of cases. Differential Diagnoses • Other Adrenal Tumors: Cortisol-producing tumors, aldosteronoma, non-functional masses like myelolipoma or cysts. • Systemic Diseases: Conditions affecting the cardiovascular, neuromuscular, and endocrine systems should be considered. Treatment • Adrenalectomy: Surgical removal of the tumor is the treatment of choice. • Preoperative Management: Phenoxybenzamine (α-adrenergic blocker) to reduce perioperative mortality by controlling hypertension and vasoconstriction. • Medical Management: For non-resectable tumors or metastasis, phenoxybenzamine is used to manage clinical signs without affecting tumor growth. Prognosis • Surgical Outcome: Favorable if perioperative complications are managed. Long-term survival is possible. • Medical Management: Limited survival, generally less than a year, with clinical signs controlled but not tumor progression.

Answer 82

Answer: **Sertoli cell tumor** Explanation The correct answer is Sertoli cell tumors. The tumor sometimes secretes estrogen and other hormones, which can lead to this syndrome. *Sertoli cell tumors are most frequently associated with feminization syndrome in dogs, including symptoms like gynecomastia, sexual attraction of males, and bilaterally symmetric alopecia. These tumors can secrete estrogen and other hormones, leading to the observed clinical signs.*

Answer 83

Answer: **It may take up to 3 days to overcome medullary washout from being polyuric and polydipsic** The correct answer is it may take up to 3 days to overcome medullary washout from being polyuric and polydipsic. DAVP is a synthetic ADH used to replace the lacking endogenous hormone. DDAVP does not induce the hypothalamus to make ADH. Medullary washout commonly occurs with CDI from prolonged PU and PD. It may take up to 3 days to get the medullary sodium concentration and concentrating mechanisms back in order. ADH receptors in the kidneys are not affected in CDI. *It may take up to 3 days to overcome medullary washout from being polyuric and polydipsic. In central diabetes insipidus (CDI), prolonged polyuria and polydipsia can lead to medullary washout, impairing the kidney’s ability to concentrate urine. Desmopressin (DDAVP) is a synthetic ADH replacement, but it may take up to 3 days for the medullary sodium concentration and concentrating mechanisms to recover. ADH receptors in the kidneys are not affected in CDI, and DDAVP does not stimulate the hypothalamus to produce ADH.* **Diabetes Insipidus in Animals: Comprehensive Veterinary Guide** Definition: Diabetes insipidus (DI) is a disorder characterized by the inability to concentrate urine, resulting in excessive urination (polyuria) and thirst (polydipsia). It is caused by a deficiency in antidiuretic hormone (ADH) or the kidneys’ inability to respond to ADH. Forms: 1. Central DI: Caused by inadequate production or secretion of ADH due to damage to the hypothalamus, infundibular stalk, or pars nervosa, often from trauma, tumors, or inflammatory lesions. 2. Nephrogenic DI: Due to the kidneys’ failure to respond to ADH, often secondary to genetic mutations or other renal dysfunctions. Pathophysiology: • Central DI: Results from damage to the hypothalamus or pituitary gland, reducing ADH production. • Nephrogenic DI: The kidneys’ receptors for ADH are dysfunctional, preventing water reabsorption despite normal or elevated ADH levels. Symptoms: • Chronic polyuria (large volumes of dilute urine) • Polydipsia (excessive water intake) • Dehydration signs if water intake is insufficient Diagnosis: • Clinical Signs: Persistent polyuria and polydipsia not due to other causes like diabetes mellitus. • Water Deprivation Test: To evaluate the body’s ability to concentrate urine under dehydration. Caution is needed to prevent severe dehydration. • ADH Response Test: Measures urine concentration response to exogenous ADH, distinguishing between central and nephrogenic DI. Treatment: • Central DI: Desmopressin acetate, a synthetic analogue of ADH, is administered to control polyuria and polydipsia. Dosage is tailored to achieve the minimal effective dose, typically given intranasally or orally. • Nephrogenic DI: Managed with dietary changes, thiazide diuretics, and ensuring constant water availability. Key Considerations: • Differential Diagnosis: Exclude other causes of polyuria such as diabetes mellitus, chronic kidney disease, and psychogenic polydipsia. • Prognosis: Lifelong management is typically required, focusing on symptom control and preventing complications like dehydration. [Diabetas insipidus](https://www.merckvetmanual.com/endocrine-system/the-pituitary-gland/diabetes-insipidus-in-animals)

Answer 84

Answer: **Concurrent endocrine disease** Explanation The correct answer is concurrent endocrine disease. Concurrent diseases such as infection, hyperadrenocorticism, and pancreatitis can commonly cause increased insulin resistance, making diabetes difficult to regulate. Amyloid deposition is a cause for DM in cats but does not change the effectiveness of insulin therapy. DM in dogs is not caused by amyloid deposition. Most insulins are supposed to be kept in the refrigerator. Feeding canned food should not contribute, so long as the diet is of good quality and adequate for diabetic regulation. Owners will commonly overdose their animals by administering additional insulin than what had been prescribed or administering insulin when the animal has not eaten. Improper storage, handling, and administration are other common causes of ineffective insulin therapy. *Concurrent endocrine disease is a common problem leading to poor glycemic control in dogs with diabetes mellitus. Conditions like infection, hyperadrenocorticism, and pancreatitis can increase insulin resistance, making diabetes harder to manage. Amyloid deposition affects cats, not dogs, and does not impact insulin therapy effectiveness. Proper insulin storage, including refrigeration, and a quality diet are essential but generally do not cause poor control. Overdosing or improper insulin administration by owners can also contribute to ineffective regulation.*

Answer 85

Answer: **Hypothyroidism** Explanation The correct answer is hypothyroidism. The clinical signs, physical exam findings, and lab work abnormalities are classical for hypothyroidism. Other common abnormalities seen with hypothyroidism include pyoderma, neuromuscular signs (ataxia, knuckling, vestibular signs, etc), markedly elevated triglycerides, and a mild normocytic, normochromic anemia. Hyperthyroidism rarely occurs in dogs. You would expect to see polyuria, polydipsia, and polyphagia with hyperadrenocorticism. *Hypothyroidism is the most likely diagnosis. The dog’s clinical signs, including weight gain despite normal eating, weak pelvic limbs, facial nerve paralysis, and a patchy haircoat, along with lab findings of normocytic, normochromic anemia and significantly elevated cholesterol, are classic for hypothyroidism. Hyperthyroidism is rare in dogs, and hyperadrenocorticism would typically present with polyuria, polydipsia, and polyphagia, not seen here.*

Answer 86

Answer:**No P waves** Explanation Based on the history and the physical exam findings of dehydration and bradycardia, you should be concerned about hypoadrenocorticism. Hypoadrenocorticism patients are typically hyperkalemic. ECG abnormalities with hyperkalemia include wide, flat, or absent P waves, widened QRS complexes, tall spiking T waves, and bradycardia. *No P waves is the expected ECG finding. The dog’s history and physical exam, including dehydration and bradycardia, suggest hypoadrenocorticism, commonly associated with hyperkalemia. Hyperkalemia can cause ECG abnormalities such as wide, flat, or absent P waves, widened QRS complexes, tall spiking T waves, and bradycardia.*

Answer 87

Answer: **Serum sodium and potassium** Explanation The correct answer is serum sodium and potassium. Addisonian patients deficient in mineralocorticoids will usually exhibit the classic findings of hyponatremia and hyperkalemia. Monitoring serum sodium and potassium concentration while treating with exogenous mineralocorticoids is the best way to determine if the level and frequency of dosage is adequate for the patient. An ACTH stimulation test can be used to monitor the efficacy of treatment of a patient with Cushing's disease, but does nothing for an Addisonian. *Serum sodium and potassium should be monitored to assess the efficacy of treatment in an Addisonian dog receiving mineralocorticoids and glucocorticoids. Addisonian patients often present with hyponatremia and hyperkalemia, so monitoring these electrolytes ensures that the dosage and frequency of mineralocorticoid supplementation are appropriate. The ACTH stimulation test is more relevant for monitoring Cushing’s disease, not Addison’s.*

Answer 88

Answer: **The patient's serum calcium should be monitored daily for about a week to check for the development of hypocalcemia.** Explanation The correct answer is the patient's serum calcium should be monitored daily for about a week to check for the development of hypocalcemia. Post-operatively, it is important to monitor for hypocalcemia daily for the first seven days regardless of the absence of clinical signs for hypocalcemia. The higher the pre-operative serum calcium concentration, the more likely the patient will become hypocalcemic post-operatively. Post-operative monitoring of serum calcium should be daily for the first seven days, then weekly for 4 weeks. Vitamin D and calcium supplementation should be given accordingly. Serum calcium concentration should be maintained in the low normal range, not below normal, to stimulate production of PTH by the parathyroid cells. *The patient’s serum calcium should be monitored daily for about a week to check for the development of hypocalcemia. After parathyroid adenoma removal, hypocalcemia can occur, especially if the pre-operative calcium levels were high. Daily monitoring for the first seven days is crucial, followed by weekly checks for four weeks. Calcium and vitamin D supplementation may be necessary, and serum calcium should be maintained in the low normal range to stimulate PTH production by the parathyroid cells.*

Answer 89

Answer: **The production and release of ADH (vasopressin) is controlled by serum osmolality and blood volume in a normal dog.** Explanation The correct answer is the production and release of ADH (vasopressin) is controlled by serum osmolality and blood volume in a normal dog. With central diabetes insipidus, the patient has a problem with the function of the hypothalamus (ADH production) and/or neurohypophysis/posterior pituitary (ADH release) so the patient cannot respond to the changes in serum osmolality or blood volume and pressure. The urine specific gravity of a CDI patient is usually 1.001-1.007. The kidneys have no problem responding to ADH in CDI patients. There is a lack of the hormone, not an over-abundance. *The production and release of ADH (vasopressin) is controlled by serum osmolality and blood volume in a normal dog. In central diabetes insipidus (CDI), the hypothalamus or posterior pituitary fails to produce or release enough ADH, so the dog cannot respond to changes in serum osmolality or blood volume. CDI patients typically have a urine specific gravity of 1.001-1.007, and their kidneys are responsive to ADH, but there is a lack of the hormone, not an excess.*

Answer 90

Answer: **Endocrinopathy** Explanation The lesion distribution is most consistent with endocrinopathy; flea allergy and sarcoptic mange would be extremely pruritic in a patient with these lesions. The dark coloration, although alarming to clients, reflects hyperpigmentation associated with inflammation, not neoplasia. *Endocrinopathy is the most likely cause of the hair loss. The lesion distribution, along with the absence of pruritus and involvement of the face, feet, and tail, is typical for an endocrine disorder. Flea allergy and sarcoptic mange would cause significant itching, and the hyperpigmentation is due to inflammation, not neoplasia like malignant melanoma.*

Answer 91

Answer: **Muscle tremors and seizures.** Explanation Early clinical signs associated with lidocaine toxicity include neurological symptoms such as seizures and tremors. Nausea and vomiting may occur, but is usually transient. Cardiovascular and respiratory depression can also occur, but usually later on in the course of clinical signs. *Lidocaine toxicity in an 8-year-old mixed breed terrier initially presents with neurological symptoms like muscle tremors and seizures. While nausea and vomiting may occur, these are usually transient. Cardiovascular and respiratory depression are possible but typically occur later in the clinical course. Early recognition and intervention are critical to manage toxicity effectively.*

Answer 92

Answer: **Patent ductus arteriosus** Explanation A patent ductus arteriosus typically is associated with a loud, continuous murmur that may be ausculted at the left heart base/axillary region. The sound is sometimes described as sounding like a "washing machine." Subaortic and pulmonic stenosis also typically have loud systolic murmurs heard best at the left heart base. An atrial septal defect is not typically associated with an intense murmur. More commonly, the murmur of ASD is Il-III/VI and is located at the left heart base due to increased flow across the pulmonary valve because of left-to-right shunting. (Note, you do not hear the flow across the atrial septum because it is of very low velocity). The life cycle of the heartworm is approximately 6 months (this patient is only 5 months old), and heartworm does not typically cause this type of murmur. Physiologic murmurs are typically a grade I-II/VI, and are low intensity. *A patent ductus arteriosus (PDA) is likely in this 5-month-old dog, given the loud, continuous "washing machine" murmur at the left heart base. PDA is associated with such murmurs, unlike atrial septal defects, which usually have softer murmurs. Heartworm infection is improbable due to the dog's age, and physiologic murmurs are typically low-intensity.* **Patent Ductus Arteriosus (PDA) in Animals** Concepts Patent ductus arteriosus (PDA) is a congenital heart defect where the ductus arteriosus fails to close after birth, leading to abnormal blood flow between the aorta and pulmonary artery. Etiology • Non-Infectious: Congenital defect present at birth. • Genetic Predisposition: More common in certain dog breeds (e.g., Poodles, German Shepherds). Pathogenesis • Normal Fetal Circulation: Blood bypasses the lungs via the ductus arteriosus. • Postnatal Changes: Ductus arteriosus should close to direct blood through the lungs. If it remains open (patent), it causes left-to-right shunting of blood, leading to volume overload of the left heart and pulmonary circulation. Symptoms • Left-to-Right Shunt: Continuous murmur (machinery murmur) at the left base, bounding pulses, and signs of left heart failure (cough, exercise intolerance). • Right-to-Left Shunt (Reverse PDA): Cyanosis, especially caudal body parts, lethargy, and exercise intolerance. Diagnostic Methods • Clinical Signs: Auscultation revealing continuous murmur, bounding femoral pulses. • Imaging: Radiographs show left atrial and ventricular enlargement; echocardiography confirms diagnosis. • Electrocardiography (ECG): Tall R waves indicating left ventricular enlargement, arrhythmias. Treatment • Left-to-Right Shunt: • Interventional: Transvenous occlusion using devices like the Amplatz Canine Ductal Occluder. • Surgical: Ligation of the ductus arteriosus. • Medical Management: CHF treatment if present. • Right-to-Left Shunt (Reverse PDA): • Medical Management: Focuses on controlling pulmonary hypertension and managing polycythemia. • Interventional/Surgical: Contraindicated unless pulmonary hypertension is managed. Prognosis • Left-to-Right Shunt: Excellent if treated early before significant clinical signs develop. • Right-to-Left Shunt: Guarded to poor due to complications from pulmonary hypertension.

Answer 93

Answer: **Isoproterenol** This ECG shows atrial fibrillation. Atenolol is a beta-blocker and will slow AV nodal conduction to decrease the ventricular response rate to atrial fibrillation. Procainamide is a class 1A anti-arrhythmic and can be used in attempts to convert atrial fibrillation to a normal sinus rhythm, though it is rarely effective. Diltiazem is a calcium channel blocker and can be used to slow AV nodal conduction and ventricular response rate. Digoxin will increase vagal tone to the AV node to slow conduction and decrease the heart rate. Isoproterenol is a nonspecific beta receptor agonist, and will increase the ventricular rate in response to atrial fibrillation, thus is inappropriate in the management of this dysrhythmia. *Isoproterenol is inappropriate for managing atrial fibrillation in small animals as it increases ventricular rate. Atenolol (beta-blocker), Digoxin (increases vagal tone), and Diltiazem (calcium channel blocker) slow AV nodal conduction, decreasing the ventricular response rate. Procainamide (class 1A anti-arrhythmic) attempts to convert atrial fibrillation to sinus rhythm, though rarely effective.*

Answer 94

Answer: **Cough** Explanation The correct answer is cough. Coughing is typically a sign of left heart failure that occurs with the development of pulmonary edema and/or bronchial compression from an enlarged left atrium. In right heart failure, tachypnea and dyspnea can develop due to pleural effusion. Hepatomegaly occurs due to venous congestion from the damming of blood into the liver. Exercise intolerance develops because a decrease in cardiac output causes a decrease in oxygenation of tissues. Muscle wasting occurs from loss of protein into effusions and from hepatic and Gl malfunction. Other signs of right heart failure include lethargy, weakness, venous distention, ascites, and peripheral edema. *Cough is not typical of right heart failure; it's usually associated with left heart failure due to pulmonary edema or bronchial compression. Right heart failure signs include tachypnea, hepatomegaly, exercise intolerance, muscle wasting, lethargy, weakness, venous distention, ascites, and peripheral edema. These result from pleural effusion, venous congestion, and decreased cardiac output.*

Answer 95

Answer: **Vasopressin** Explanation The correct answer is vasopressin. Epinephrine and phenylephrine are adrenergic vasoconstrictors. Isoproterenol and dobutamine cause vasodilation. Vasopressin (also known as anti-diuretic hormone) is a V-1 receptor, non-adrenergic, vasoconstrictor. *Vasopressin is a non-adrenergic vasoconstrictor used in dogs. Unlike epinephrine and phenylephrine, which are adrenergic vasoconstrictors, and isoproterenol and dobutamine, which cause vasodilation, vasopressin acts on V-1 receptors to induce vasoconstriction.*

Answer 96

Answer: **Enalapril** Explanation The correct answer is enalapril. All others would be contraindicated. Enalapril is an ACE-inhibitor, which blunts the adverse effects of the renin-agiotensin-aldosterone system thereby reducing sodium and fluid retention. Additionally, ACE-inhibitors cause mild vasodilation by preventing the production of angiotensin-ll, which reduces ventricular afterload. Lastly, enalapril and other ACE-inhibitors are protective to cardiac muscle by blunting aldosterone and other hormones which induce cardiac remodeling. *Enalapril is indicated for the treatment of dilated cardiomyopathy (DCM) in dogs. As an ACE inhibitor, it reduces the adverse effects of the renin-angiotensin-aldosterone system, decreasing sodium and fluid retention, causing mild vasodilation, and reducing ventricular afterload. Additionally, enalapril helps protect cardiac muscle by preventing harmful cardiac remodeling. Other medications like atropine, prednisone, and adriamycin are contraindicated in this condition.* **Dilated Cardiomyopathy (DCM) in Dogs and Cats** Definitions and Causative Agents: • DCM: A disease characterized by the progressive loss of myocyte number and/or function, leading to decreased cardiac contractility. • Causative Agents: Genetic predispositions, nutritional deficiencies (e.g., taurine in cats), chemical (e.g., doxorubicin), viral (e.g., parvovirus), and idiopathic causes. Clinical Findings: • Symptoms: Often subclinical in early stages; advanced cases exhibit signs of heart failure including cough, dyspnea, exercise intolerance, syncope, and weight loss. • Lesions: Enlarged heart with thin walls, particularly affecting the left ventricle and atrium. • Physical Exam: Soft systolic heart murmur, gallop rhythm, weak femoral pulses, arrhythmias (ventricular ectopy in Doberman Pinschers and Boxers, atrial fibrillation in giant breeds). Diagnosis: • Echocardiography: Best method to confirm diagnosis, showing left ventricular and atrial enlargement and reduced contractility. • ECG: Detects ventricular premature complexes, ventricular tachycardia, and atrial fibrillation. • Radiographs: Reveal cardiomegaly and signs of congestive heart failure (CHF). Treatment: • Medications: • Pimobendan: Increases contractility and reduces preload/afterload. • ACE Inhibitors (e.g., enalapril, benazepril): Mitigate the effects of the renin-angiotensin-aldosterone system (RAAS). • Furosemide: Diuretic for managing CHF. • Antiarrhythmics: Used particularly in breeds prone to ventricular ectopy. • Taurine Supplementation: Effective in taurine-responsive DCM cases. • Supportive Care: Oxygen therapy, dietary management. Prognosis: • Dogs: Poor long-term prognosis, with most dying within 6 months of diagnosis; better outcomes in taurine-responsive cases. • Cats: Severe respiratory signs, poor prognosis in non-taurine-responsive cases, better prognosis if taurine-responsive and treated early.

Answer 97

Answer: **Complete heart block.** The correct answer is complete heart block. The ECG shows frequent P waves and two ventricular escape beats from different foci. Complete heart block typically results from degeneration and fibrosis of the cardiac conduction system. The animal then relies on a slow escape rate, which often results in clinical symptoms of weakness and collapse. Sinus arrest would be seen as periods of flat line on the ECG with no atrial activity; normal sinus rhythm would show conduction of the P waves with QRS complexes following. Ventricular premature complexes is incorrect because the above 2 ventricular beats are escapes, they are not premature. Atrial premature complexes is wrong as the atrial rhythm is normal. *The diagnosis is complete heart block. The ECG shows frequent P waves with two ventricular escape beats from different foci, indicating a complete dissociation between atrial and ventricular activity. Complete heart block is often due to degeneration and fibrosis of the cardiac conduction system, leading to a slow escape rate, which can cause clinical symptoms like weakness and collapse. Sinus arrest, normal sinus rhythm, ventricular premature complexes, and atrial premature complexes do not match this ECG pattern.*

Answer 98

Answer: **Balloon valvuloplasty** Explanation The correct answer is balloon valvuloplasty. This procedure is performed by inserting a catheter into either a jugular vein or a femoral vein and advancing it into the region of stenosis at the pulmonic outflow tract. Once in place, a balloon surrounding the catheter is inflated to stretch the stenotic region open. Surgical valvulotomy or patch grafting is the treatment used for severe cases that cannot be balloon-dilated. *Balloon valvuloplasty is the treatment of choice for pulmonic stenosis in dogs. It involves inserting a catheter through the jugular or femoral vein to the pulmonic outflow tract and inflating a balloon to stretch the stenotic region. Surgical valvulotomy or patch grafting is reserved for severe cases unresponsive to balloon dilation.* **Condition Overview: Pulmonic Stenosis (PS) in Dogs** • Definition: Pulmonic Stenosis (PS) is a congenital heart defect characterized by the obstruction of blood flow from the right ventricle to the pulmonary artery due to narrowing at, below, or above the pulmonary valve. • Classification: • Subvalvular: Below the valve. • Valvular: At the valve (most common). • Supravalvular: Above the valve. • Valvular Subtypes: • Type A: Leaflet fusion with systolic doming. • Type B: Thickened, hypomobile leaflets with annulus hypoplasia (associated with poorer prognosis). Pathophysiology: • Hemodynamic Impact: PS increases resistance to blood flow from the right ventricle, leading to right ventricular hypertrophy and, if severe, right-sided congestive heart failure (RCHF). • Doppler Gradient (DG): • Mild PS: DG < 50 mmHg. • Moderate PS: DG between 50 and 80 mmHg. • Severe PS: DG > 80 mmHg. • Consequences of Severe PS: • Increased right ventricular pressure. • Decreased cardiac output. • Potential for arrhythmias, syncope, RCHF, and sudden death. Clinical Signs: • Symptoms: • Exercise intolerance. • Syncope (fainting). • Signs of RCHF: Ascites, pleural effusion, hepatomegaly. • Prognostic Factors: • Age at Diagnosis: Younger age at diagnosis is associated with worse outcomes. • Valve Morphology: Type B morphology correlates with a poorer prognosis due to more severe malformations. • Presence of Clinical Signs: Clinical signs at diagnosis are a strong predictor of a poorer prognosis. Diagnostic Evaluation: • Echocardiography: • Assess severity of PS, right ventricular hypertrophy, and tricuspid regurgitation. • Valvular Morphology: Important to differentiate between Type A and Type B for prognosis. • Doppler Echocardiography: Measures the peak transvalvular pulmonary gradient to assess the severity of stenosis. Treatment Options: • Pulmonary Balloon Valvuloplasty (PBV): • Indications: • Severe PS (DG > 80 mmHg). • Moderate PS with clinical signs or rapidly worsening condition. • Outcomes: • PBV significantly improves survival in dogs with severe PS. • Dogs with moderate PS may benefit, particularly if symptomatic. • Medical Management: • Beta-blockers (Atenolol): • Dose: 0.5 mg/kg orally every 12-24 hours. • Indications: To manage symptoms in both PBV and non-PBV patients, particularly in moderate to severe PS. • Atenolol may be discontinued post-PBV unless there is a poor reduction in DG or significant right ventricular hypertrophy persists. Prognosis: • Survival Rates: • Severe PS without PBV: High mortality, particularly in the first year (53%). • Severe PS with PBV: Significantly lower mortality (4-6% in the first year). • Moderate PS: Generally favorable prognosis, though clinical signs indicate a higher risk of cardiac-related death. • Long-term Considerations: • Right Ventricular Function: Critical in determining the prognosis post-PBV. Poor right ventricular function often leads to poor outcomes even after intervention. Risk Factors: • Negative Predictors of Survival: • Younger Age at Diagnosis: High hazard ratio (HR 12.82, P<0.01) indicating increased risk of cardiac-related death. • Type B Valve Morphology: Associated with a higher risk of restenosis and poorer outcomes (HR 10.20, P<0.01). • Presence of Clinical Signs: Strongly correlated with cardiac death, particularly in severe PS (HR 5.41, P<0.01). Considerations for Specific Cases: • Right-Sided Congestive Heart Failure (RCHF): • Prognosis: Poor, with a median survival time of 12 months. • Treatment Decisions: PBV may be beneficial, but careful evaluation of right ventricular function is necessary before proceeding. • Syndromic Associations: • Type B PS in brachycephalic breeds (e.g., Bulldogs, Boxers) may resemble genetic syndromes like Noonan syndrome in humans, characterized by congenital cardiac malformations. Clinical Guidelines: • Intervention Timing: Early intervention, particularly before the onset of clinical signs, may improve outcomes. • Post-Treatment Monitoring: Regular echocardiographic evaluations post-PBV are crucial, particularly for monitoring DG and right ventricular function.

Answer 99

Answer: **strict activity restriction of the dog is very important once medical treatment is initiated** Explanation The correct answer is strict activity restriction of the dog is very important once treatment is initiated. Dogs should be restricted in activity at least 4-6 weeks post treatment to decrease the likelihood of thromboembolic events and to allow the lungs to recover from injury due to worm death. Dogs are not as likely to develop right heart failure after treatment of heartworm disease if they were previously clinically normal. Ivermectin is often used to prevent heartworm disease and for treating microfilariae, but the treatment of choice for adult worms is melarsomine IM. Doxycycline is often used to treat the Wolbachia bacteria that are often found with heartworms, but is ineffective at treating the worms themselves. *Strict activity restriction is crucial once heartworm treatment starts, to reduce thromboembolic events and allow lung recovery post worm death. Dogs clinically normal pre-treatment rarely develop right heart failure afterward. Ivermectin prevents heartworm and treats microfilariae, but melarsomine IM treats adult worms. Doxycycline targets Wolbachia bacteria associated with heartworms, not the worms themselves.* **General Information Heartworm disease in animals:** • Causative Agent: Dirofilaria immitis (filarial nematode). • Vector: Mosquitoes (e.g., Aedes, Anopheles, Culex). • Species Affected: Primarily dogs, but also cats, ferrets, and occasionally other species like coyotes and foxes. Pathogenesis: • Life Cycle: Mosquitoes transmit infective larvae (L3), which migrate into the host, molt, and mature into adults in the pulmonary arteries. • Pulmonary Disease: The disease affects the pulmonary arteries, causing inflammation, endarteritis, and pulmonary hypertension. Long-term infections can lead to chronic lesions, scarring, and heart failure. • Immunological Response: Wolbachia bacteria within the heartworms contribute to the inflammatory response and disease severity. Antigenic stimulation leads to immune responses, causing further damage. Clinical Findings: • Dogs: Most common signs include cough, exercise intolerance, and signs of right-sided heart failure (e.g., ascites). Severe cases can lead to caval syndrome with signs like hemolysis, anemia, and hepatorenal dysfunction. • Cats and Ferrets: Often subclinical or mild, but severe cases can present with respiratory distress, weight loss, lethargy, vomiting, and sudden death. Cats can suffer from HARD (heartworm-associated respiratory disease). Diagnosis: • Serology: Antigen testing is the primary method in dogs, while antibody testing is more useful in cats due to the lower sensitivity of antigen tests in cats. • Microfilaria Detection: Direct smear or modified Knott test; useful as an adjunct in dogs. • Imaging: Thoracic radiography, echocardiography (particularly important in cats and ferrets). Treatment: • Dogs: Adulticide therapy with melarsomine (an organic arsenic compound), typically in a three-dose protocol. Adjunct therapy with doxycycline to target Wolbachia. Supportive care and exercise restriction are crucial. • Cats and Ferrets: No safe adulticide therapy; treatment focuses on managing symptoms with corticosteroids, oxygen therapy, and occasionally surgical removal of heartworms. Prevention: • Macrocyclic Lactones: Regular administration of ivermectin, milbemycin, selamectin, or moxidectin for prevention. For dogs, these drugs also serve as microfilaricides. Stages of Disease: 1. Stage I: Subclinical or minimal signs. 2. Stage II: Mild to moderate signs, typically including cough. 3. Stage III: Severe signs, such as weight loss, respiratory distress, and right heart failure. 4. Stage IV: Caval syndrome with severe cardiopulmonary compromise. https://www.merckvetmanual.com/circulatory-system/heartworm-disease/heartworm-disease-in-dogs-cats-and-ferrets

Answer 100

Answer: **Vasopressin** Explanation The correct answer is vasopressin. Epinephrine and phenylephrine are adrenergic vasoconstrictors. Isoproterenol and dobutamine cause vasodilation. Vasopressin (also known as anti-diuretic hormone) is a V-1 receptor, non-adrenergic, vasoconstrictor.

Answer 101

Answer: **Medical management with Beta Blockers** Explanation The correct answer is medical management with beta blockers. Beta blockers such as atenolol are often used to reduce myocardial oxygen demand, thus reducing the frequency of ventricular arrhythmias. The owners should also be warned that the dog will need prophylactic antibiotics for any situation in which the dog may develop a bacteremia, since it is at high risk of developing infective endocarditis. Balloon dilation by catheterization can be attempted in some patients, but the results are usually no better than medical therapy with beta blockers. Surgical repair is difficult, expensive, and does not give very good results either. There is no indication for furosemide unless the dog is in heart failure. *Medical management with beta blockers, such as atenolol, is the most common treatment for aortic stenosis in dogs. Beta blockers reduce myocardial oxygen demand and ventricular arrhythmias. Prophylactic antibiotics are needed to prevent infective endocarditis. Balloon dilation offers no better results than beta blockers, and surgical repair is challenging and less effective. Furosemide is only indicated for heart failure.*

Answer 102

Answer: **Echocardiogram** The breed, clinical history of syncope, radiographic findings, and auscultation findings are most consistent with aortic stenosis. Echocardiography would be the best method for diagnosing the disease in which you would find left ventricular concentric hypertrophy, stenosis of the aortic outflow tract, and post-stenotic dilatation of the ascending aorta. A Holter monitor is the test of choice for arrhythmogenic right ventricular cardiomyopathy (ARVC) which is also seen in Boxers and causes syncope but does not fit with the physical exam or radiographic findings. Also called Boxer cardiomyopathy, ARVC is a disease associated with fibrofatty infiltrate into the right ventricle resulting in electrical conduction disturbances and resultant VPCs. A CT scan would not add more information, and cardiac motion typically causes resolution problems on thoracic CT scans. The signs are not consistent with heartworm, which is primarily a right heart problem, or with hemolytic anemia, which a Coombs' test might be useful for. *Echocardiogram is best for confirming aortic stenosis in this 1.5-year-old Boxer, given the breed, syncope, and findings of a grade 4/6 systolic murmur, left ventricular and atrial enlargement, and ascending aorta dilation. It reveals left ventricular concentric hypertrophy, aortic outflow tract stenosis, and post-stenotic dilation. Holter ECG monitors are for arrhythmogenic right ventricular cardiomyopathy, which doesn't match this case's findings.*

Answer 103

Answer: **Aortic stenosis** Explanation The correct answer is aortic stenosis. The breed, clinical history of syncope, radiographic findings, and auscultation findings are most consistent with aortic stenosis. Echocardiography would be the best method for diagnosing the disease in which you would find left ventricular hypertrophy, stenosis of the aortic outflow tract, and post-stenotic dilatation of the aorta. Pulmonic stenosis would result in changes in the right heart and pulmonary outflow tract. Myxomatous degeneration of the mitral valve typically occurs in older animals, results in a murmur heard best at the left apex, and would not cause a dilation of the ascending aorta. Boxer cardiomyopathy (or arrhythmogenic right ventricular cardiomyopathy) is principally an electrical disease causing frequent VPCs to occur. Dilation of the heart may occur in 10-15% of cases. The best way to diagnose Boxer cardiomyopathy is with a 24 hour cardiac Holter monitor. *The most likely diagnosis is aortic stenosis. The breed, syncope, radiographic findings (mildly enlarged left ventricle and atrium, segmental enlargement of the ascending aorta), and auscultation (4/6 left systolic murmur at heart base) support this. Echocardiography reveals left ventricular hypertrophy, aortic outflow tract stenosis, and post-stenotic aorta dilation. Pulmonic stenosis affects the right heart, myxomatous mitral valve degeneration affects older dogs with a murmur at the left apex, and Boxer cardiomyopathy involves frequent VPCs and is diagnosed with a Holter monitor.*

Answer 104

Answer: **Atrial septal defect with systemic hypertension** Explanation The correct answer is atrial septal defect with systemic hypertension. This dog's polycythemia developed due to shunting of venous blood into the arterial circulation (aka right-to-left shunting) leading to hypoxemia and an increased drive for erythropoiesis and secondary polycythemia. This can be caused by any of the other 3 answer choices. An atrial septal defect with systemic hypertension results in oxygenated blood shunting into the venous circulation or left-to-right shunting, which usually does not cause hypoxemia. *Atrial septal defect with systemic hypertension cannot explain the findings. This condition causes left-to-right shunting, leading to oxygenated blood entering the venous circulation, not hypoxemia. The dog's polycythemia (hematocrit 70%) suggests right-to-left shunting, leading to hypoxemia and increased erythropoiesis. This can be caused by PDA with pulmonary hypertension, atrial septal defect with tricuspid stenosis, or Tetralogy of Fallot.*

Answer 105

Answer: **Atrial septal defect with systemic hypertension** Explanation The correct answer is atrial septal defect with systemic hypertension. This dog's polycythemia developed due to shunting of venous blood into the arterial circulation (aka right-to-left shunting) leading to hypoxemia and an increased drive for erythropoiesis and secondary polycythemia. This can be caused by any of the other 3 answer choices. An atrial septal defect with systemic hypertension results in oxygenated blood shunting into the venous circulation or left-to-right shunting, which usually does not cause hypoxemia. *Atrial septal defect with systemic hypertension cannot explain the findings. This condition causes left-to-right shunting, leading to oxygenated blood entering the venous circulation, not hypoxemia. The dog's polycythemia (hematocrit 70%) suggests right-to-left shunting, leading to hypoxemia and increased erythropoiesis. This can be caused by PDA with pulmonary hypertension, atrial septal defect with tricuspid stenosis, or Tetralogy of Fallot.* **Key Information on Patent Ductus Arteriosus (PDA) in Animals** Definitions • Patent Ductus Arteriosus (PDA): A congenital heart defect where the ductus arteriosus fails to close after birth, causing abnormal blood flow between the aorta and pulmonary artery. Pathophysiology • Fetal Circulation: Blood bypasses the lungs via the ductus arteriosus. • Postnatal Changes: Normally closes to become the ligamentum arteriosum. • PDA Pathology: Persistent patency causes left-to-right shunting, leading to volume overload and left heart failure. Clinical Findings • Symptoms: Continuous murmur, bounding femoral pulses, left heart failure (pulmonary edema). • Reverse PDA: Right-to-left shunting, differential cyanosis, polycythemia. • Diagnostic Tests: Radiography (left atrial/ventricular enlargement), echocardiography (turbulent flow in pulmonary artery). Diagnosis • Electrocardiography: Tall R waves in lead II. • Radiography: Aortic ductus diverticulum, left heart enlargement. • Echocardiography: Continuous turbulence in pulmonary artery, left heart enlargement. Treatment • Early Closure: Recommended to prevent heart failure. • Methods: Interventional transvenous occlusion (ACDO), surgical ligation. • Reverse PDA Management: Medical management of pulmonary hypertension and polycythemia, not closure. https://www.merckvetmanual.com/circulatory-system/congenital-and-inherited-anomalies-of-the-cardiovascular-system/patent-ductus-arteriosus-in-animals?redirectid=27882 **Tetralogy of Fallot in Animals** Definition: • Congenital heart defect with four components: pulmonic stenosis, ventricular septal defect, right ventricular hypertrophy, and overriding aorta. Affected Species: • Dogs (e.g., Keeshonds, English Bulldogs), cats. Clinical Signs: • Cyanosis, exercise intolerance, stunted growth, collapse, seizures. • Loud ejection heart murmur, precordial thrill. Diagnosis: • Echocardiography: Confirms structural defects. • Radiographs: Right heart enlargement. • ECG: Right ventricular enlargement. Treatment: • Beta-adrenergic blockers to manage outflow obstruction. • Periodic phlebotomy for polycythemia. • Surgical options: Palliative techniques, valvuloplasty. Control: • Manage based on severity, supportive care, and specific surgical interventions. https://www.merckvetmanual.com/circulatory-system/congenital-and-inherited-anomalies-of-the-cardiovascular-system/tetralogy-of-fallot-in-animals?query=tetralogy%20of%20fallot

Answer 106

Answer: **Surgical ligation is the most appropriate form of treatment for a cylinder-shaped PDA** Explanation The correct answer is surgical ligation of the PDA is the most appropriate form of treatment. A large cylindrical PDA is unlikely amenable to closure via traditional coil embolization. Most canine PDAs are funnel-shaped with the smaller end of the funnel attached to the pulmonary artery, and the wider end attached to the aorta. The funnel shape is what allows the coils to lodge in place and cause closure of the PDA. Coils would not stay in place in a large, cylindrical PDA, so surgical ligation is the treatment of choice for this patient. There are newer nickel-titanium devices (Amplatz Canine Ductal Occluder) that show promise for minimally-invasive closure of PDAs which do not taper, but this answer was not provided. Ameroid constrictor rings are typically used for ligating hepatic shunts, and not for PDAs. Medical management with diuretics and heart drugs are only indicated prior to correction of the PDA if the dog is in heart failure. *Surgical ligation is the most appropriate treatment for a large, cylinder-shaped PDA. Traditional coil embolization is ineffective for cylindrical PDAs, as coils need a funnel shape to lodge properly. The newer Amplatz Canine Ductal Occluder might be effective but wasn't an option. Ameroid constrictor rings are for hepatic shunts, and medical management with furosemide and enalapril is only for pre-correction heart failure.* **Heartworm Disease in Small Animals.** Causative Agent: • Dirofilaria immitis: A parasitic nematode transmitted by mosquitoes, causing heartworm disease in dogs, cats, and ferrets. Life Cycle: • Mosquitoes acquire microfilariae from infected hosts, developing into L3 larvae. These larvae migrate to the heart and pulmonary arteries, maturing into adults in 6-7 months. Pathophysiology: • Adult heartworms cause pulmonary artery inflammation, vascular damage, and pulmonary hypertension. Severe infections lead to right-sided heart failure and caval syndrome. In cats, heartworm-associated respiratory disease (HARD) is due to the immune response to dying larvae. Clinical Signs: • Dogs: Cough, exercise intolerance, weight loss, dyspnea, hemoptysis, syncope, ascites. • Cats: Coughing, dyspnea, vomiting, weight loss, sudden death. • Ferrets: Similar to dogs but with more pronounced signs due to their small size. Diagnosis: • Serology: Antigen tests (dogs, cats, ferrets), antibody tests (cats). • Microfilaria Detection: Direct smear, modified Knott test. • Imaging: Thoracic radiography, echocardiography (especially important in cats). Treatment: • Dogs: Melarsomine (3 injections), doxycycline (to eliminate Wolbachia), supportive care. Preventive medications like ivermectin, milbemycin, moxidectin, or selamectin. • Cats/Ferrets: Primarily supportive care. Doxycycline may help, but adulticide therapy is generally avoided. Prevention: • Macrocyclic lactones: Regular prophylaxis is crucial (e.g., ivermectin, milbemycin). Special Considerations: • Wolbachia: Symbiotic bacteria essential for heartworm survival, targeted with doxycycline to enhance treatment efficacy.

Answer 107

Answer: **Ivermectin once a month** Explanation The correct answer is ivermectin once monthly. Diethylcarbamazine (DEC) can be used to prevent heartworm, but is administered once daily. Milbemycin oxime is another preventative used once monthly. *Ivermectin once a month is the correct heartworm prevention treatment. Diethylcarbamazine (DEC) is used daily, and Milbemycin oxime is another monthly preventative. Other options, like Milbemycin twice daily or Ivermectin daily, are incorrect.*

Answer 108

Answer: **Propofol** Explanation The correct answer is propofol. Ketamine causes an increase in heart rate and blood pressure. It is considered seizureogenic and has poor muscle relaxation effects, however it provides good analgesia. Thiopental is an ultra fast acting thiobarbiturate that causes an increased heart rate, increased blood pressure, and decreased cardiac contractility. It is also an arrhythmogenic agent. Morphine is an opioid that causes bradycardia. Propofol does not result in any significant cardiac changes. It is ultra-short in duration, can cause apnea and myoclonus, and is considered anticonvulsive. It may cause a mild bradycardia but you mainly see that when used in combination with other opiates. More recently propofol has been associated with myocardial depression and hypotension in critically ill dogs and may not be the induction agent of choice as a result. Despite these findings, propofol still has the least effect on heart rate. *Propofol has the least effect on heart rate. Ketamine increases heart rate and blood pressure, Thiopental increases heart rate and blood pressure but decreases cardiac contractility, and Morphine causes bradycardia. Propofol primarily causes mild bradycardia when combined with other opiates and has minimal cardiac impact, making it the best option regarding heart rate stability.*

Answer 109

Answer: **Diltiazem slows the heart by inhibiting the influx of calcium into the myocardial cells.** Explanation The correct answer is diltiazem slows the heart by inhibiting the influx of calcium into the myocardial cells. Diltiazem is a calcium channel blocker used to slow the heart to treat supraventricular tachycardias, hypertrophic cardiomyopathy, and hypertension. *Diltiazem slows the heart by inhibiting the influx of calcium into myocardial cells. It is a calcium channel blocker used to manage supraventricular tachycardias, hypertrophic cardiomyopathy, and hypertension. It does not antagonize beta adrenergic receptors or act as a beta adrenergic agonist.*

Answer 110

Answer: **Acanthocheilonema reconditum** Explanation The correct answer is Acanthocheilonema reconditum (previously Dipetalonema reconditum). Acanthocheilonema reconditum is a blood parasite that looks similar to the microfilariae of Dirofilaria immitis, the agent of Heartworm disease. The two parasites must be differentiated because Acanthocheilonema reconditum is not pathogenic and is therefore not treated. Uncinaria stenocephala, Strongyloides stercoralis, and Filaroides osleri would not be found in the blood. *The parasite that must be ruled out in a dog with microfilariae in the peripheral blood is Acanthocheilonema reconditum. This blood parasite resembles Dirofilaria immitis (heartworm), but unlike heartworm, A. reconditum is not pathogenic and does not require treatment.*

Answer 111

Answer: **Acanthocheilonema reconditum** Explanation The correct answer is Acanthocheilonema reconditum (previously Dipetalonema reconditum). Acanthocheilonema reconditum is a blood parasite that looks similar to the microfilariae of Dirofilaria immitis, the agent of Heartworm disease. The two parasites must be differentiated because Acanthocheilonema reconditum is not pathogenic and is therefore not treated. Uncinaria stenocephala, Strongyloides stercoralis, and Filaroides osleri would not be found in the blood. *The parasite that must be ruled out in a dog with microfilariae in the peripheral blood is Acanthocheilonema reconditum. This blood parasite resembles Dirofilaria immitis (heartworm), but unlike heartworm, A. reconditum is not pathogenic and does not require treatment.*

Answer 112

Answer: **it is a direct measure of blood pressure in the cranial vena cava** Explanation The correct answer is it is a direct measure of blood pressure in the cranial vena cava. Venous blood volume, venous vessel tone, and cardiac output determine the CVP. CVP is an estimate of preload, not a direct measurement. Cardiac output is one of the factors along with venous tone and venous blood volume in obtaining CVP. Afterload is the force against which the myocardium must contract. *Central venous pressure (CVP) is a direct measure of blood pressure in the cranial vena cava. It is influenced by venous blood volume, venous vessel tone, and cardiac output. CVP estimates preload but does not directly measure it. Afterload is the resistance against which the myocardium contracts.*

Answer 113

Answer: **First degree AV block** Explanation The correct answer is first degree AV block as this is a very subtle prolongation between the P and the R wave which can usually only be recognized by evaluation of an ECG strip. *First degree AV block is least likely to be ausculted in a dog, as it involves a subtle prolongation between the P and R wave detectable only via ECG. Other abnormal heart sounds like atrial fibrillation, gallop rhythm, and sinus arrhythmia are more easily ausculted.*

Answer 114

Answer: **Left atrial and left ventricular enlargement with pulmonary hyperperfusion** Explanation The correct answer is left atrial and left ventricular enlargement with pulmonary hyperperfusion. In dogs with a VSD, the shunt occurs during systole when both ventricles are contracting so blood is shunted from the left ventricle almost directly into the pulmonary artery. The right ventricle acts as a conduit between the left ventricle and pulmonary artery and is less commonly affected by the shunted blood. The excess blood flow is found in the pulmonary vasculature, left atrium, and left ventricle, thus enlarging these structures. *The most likely radiographic appearance for a dog with a larger left to right ventricular septal defect and advanced sequelae is left atrial and left ventricular enlargement with pulmonary hyperperfusion. In VSD, blood shunts from the left ventricle to the pulmonary artery during systole, causing excess blood flow in the pulmonary vasculature, left atrium, and left ventricle, enlarging these structures.*

Answer 115

Answer: **Mitral valve prolapse** Explanation The correct answer is mitral valve prolapse. Note how the mitral valve bends back into the left atrium consistent with mitral valve prolapse. The valve is also thick and mitral regurgitation is likely, which fits with the heart murmur reported. The left ventricular lumen is dilated and walls appear of normal thickness, so concentric hypertrophy is not present. The pulmonic valve is not seen in this image plane. The right ventricle is not well seen either, but in the very near field, the right ventricular wall appears normal. What can be seen of the tricuspid valve does not appear to have any vegetations consistent with endocarditis. *The echocardiogram shows mitral valve prolapse, evidenced by the mitral valve bending back into the left atrium. The valve is thickened, likely causing mitral regurgitation, consistent with the reported heart murmur. The left ventricular lumen is dilated with normal wall thickness, ruling out concentric hypertrophy. The pulmonic valve and right ventricle are not visible, and the tricuspid valve lacks vegetations indicative of endocarditis.*

Answer 116

Answer: **Eccentric hypertrophy of the left atrium and left ventricle** Explanation The correct answer is eccentric hypertrophy of the left atrium and left ventricle. Mitral regurgitation is the process of blood flowing back from the left ventricle to the left atrium due to a defect in the valve. The excess blood flow causes volume overload of the left atrium leading to eccentric hypertrophy or dilation of the chamber. The excess blood volume will then return to the left ventricle during the next diastole, resulting in dilation and eccentric hypertrophy of the left ventricle as well. Concentric hypertrophy occurs in cardiac chambers when they are pressure overloaded, such as in the case of pulmonic stenosis or aortic stenosis. *Mitral regurgitation in dogs leads to eccentric hypertrophy of the left atrium and left ventricle. The regurgitation causes volume overload, resulting in dilation and eccentric hypertrophy of the left atrium. This excess blood then flows into the left ventricle during diastole, causing its dilation and eccentric hypertrophy. Concentric hypertrophy is associated with pressure overload conditions like pulmonic or aortic stenosis.*

Answer 117

Answer: **Polycythemia** Explanation Tetralogy of Fallot is a congenital defect of the heart which includes pulmonic stenosis (not aortic stenosis), dextro-positioned aorta (over-riding), RIGHT ventricular hypertrophy, and a ventricular septal defect. It causes shunting of venous blood across the VSD into the arterial circulation which leads to hypoxemia, and an increased drive for erythropoiesis, causing polycythemia. Affected animals tend be underdeveloped in size and have a history of exercise intolerance, dyspnea, tachypnea, or syncope due to hypoxemia. Thoracic radiographs usually show a normal to mildly enlarged cardiac silhouette with right ventricular enlargement and pulmonary hypoperfusion due to the shunting of venous blood into the arterial circulation. *Polycythemia is consistent with Tetralogy of Fallot in dogs. This congenital defect includes pulmonic stenosis, dextro-positioned aorta, right ventricular hypertrophy, and a ventricular septal defect, leading to venous blood shunting into the arterial circulation. This results in hypoxemia, driving erythropoiesis and causing polycythemia. Affected dogs often exhibit exercise intolerance, dyspnea, tachypnea, or syncope, with thoracic radiographs showing a normal to mildly enlarged cardiac silhouette, right ventricular enlargement, and pulmonary hypoperfusion.*

Answer 118

Answer: **Polycythemia** Explanation Tetralogy of Fallot is a congenital defect of the heart which includes pulmonic stenosis (not aortic stenosis), dextro-positioned aorta (over-riding), RIGHT ventricular hypertrophy, and a ventricular septal defect. It causes shunting of venous blood across the VSD into the arterial circulation which leads to hypoxemia, and an increased drive for erythropoiesis, causing polycythemia. Affected animals tend be underdeveloped in size and have a history of exercise intolerance, dyspnea, tachypnea, or syncope due to hypoxemia. Thoracic radiographs usually show a normal to mildly enlarged cardiac silhouette with right ventricular enlargement and pulmonary hypoperfusion due to the shunting of venous blood into the arterial circulation. *Polycythemia is consistent with Tetralogy of Fallot in dogs. This congenital defect includes pulmonic stenosis, dextro-positioned aorta, right ventricular hypertrophy, and a ventricular septal defect, leading to venous blood shunting into the arterial circulation. This results in hypoxemia, driving erythropoiesis and causing polycythemia. Affected dogs often exhibit exercise intolerance, dyspnea, tachypnea, or syncope, with thoracic radiographs showing a normal to mildly enlarged cardiac silhouette, right ventricular enlargement, and pulmonary hypoperfusion.*

Answer 119

Answer: **Tricuspid dysplasia** Explanation The correct answer is tricuspid dysplasia. Tricuspid dysplasia is similar to mitral valve dysplasia in the irregular valve leaflets, chordae tendinae, or papillary muscles of the valve. Labrador Retrievers, German Shepherd Dogs, and other large breed males are predisposed to the disease. Signs of right heart failure, such as ascites and hepatomegaly occur in advanced disease. The prognosis for these animals is guarded to poor depending on the severity of the regurgitation. Pulmonic stenosis causes a pressure overload of the right heart and causes concentric hypertrophy, which may or may not be detectable by radiography. The murmur with PS is heard better at the left heart base. Hemangiosarcoma and hepatocellular carcinoma are less likely in a 7 month old puppy. *Tricuspid dysplasia is the most likely diagnosis for the 7-month-old Labrador Retriever presenting with lethargy, distended abdomen, and exercise intolerance. The condition involves irregular tricuspid valve leaflets, chordae tendineae, or papillary muscles, leading to right atrial and ventricular enlargement, ascites, and hepatomegaly. Labrador Retrievers and other large breed males are predisposed. Pulmonic stenosis would cause right heart concentric hypertrophy and a murmur at the left heart base. Hemangiosarcoma and hepatocellular carcinoma are less likely in such a young dog.*

Answer 120

Answer: **To increase arterial blood pressure** Explanation The correct answer is to increase blood pressure. High doses of dopamine are used as an alpha agonist to increase peripheral resistance and increase blood pressure. It is often used during anesthesia and emergency situations to alleviate hypotension. *Dopamine is often used to increase arterial blood pressure. At high doses, dopamine acts as an alpha agonist, increasing peripheral resistance and blood pressure. It is commonly administered during anesthesia and in emergency situations to counteract hypotension.*

Answer 121

Answer: **Surgical ligation is the most appropriate form of treatment for a cylinder-shaped PDA** Explanation The correct answer is surgical ligation of the PDA is the most appropriate form of treatment. A large cylindrical PDA is unlikely amenable to closure via traditional coil embolization. Most canine PDAs are funnel-shaped with the smaller end of the funnel attached to the pulmonary artery, and the wider end attached to the aorta. The funnel shape is what allows the coils to lodge in place and cause closure of the PDA. Coils would not stay in place in a large, cylindrical PDA, so surgical ligation is the treatment of choice for this patient. There are newer nickel-titanium devices (Amplatz Canine Ductal Occluder) that show promise for minimally-invasive closure of PDAs which do not taper, but this answer was not provided. Ameroid constrictor rings are typically used for ligating hepatic shunts, and not for PDAs. Medical management with diuretics and heart drugs are only indicated prior to correction of the PDA if the dog is in heart failure. *Surgical ligation is the most appropriate treatment for a large, cylinder-shaped PDA in a 1-year-old German Shepherd Dog. Traditional coil embolization is ineffective for cylindrical PDAs, as coils require a funnel shape to lodge properly. Newer devices like the Amplatz Canine Ductal Occluder show promise but weren't options here. Ameroid constrictor rings are for hepatic shunts, and medical management with diuretics and heart drugs is only for pre-correction heart failure.*

Answer 122

Answer: **Hypotension** Explanation The correct answer is hypotension. Phenothiazines cause sedation, but do not provide analgesia. They may decrease hematocrit due to splenic sequestration of red blood cells. They decrease the sensitivity of the myocardium to catecholamine-induced arrhythmias. *Phenothiazines cause hypotension in dogs. They provide sedation without analgesia, may decrease hematocrit due to splenic sequestration of red blood cells, and decrease myocardial sensitivity to catecholamine-induced arrhythmias.*

Answer 123

Answer: **Atrial fibrillation** Explanation Patients with enlarged atria can develop the arrhythmia atrial fibrillation. Atrial fibrillation is characterized by a rapid irregularly irregular rhythm. Primary atrial fibrillation occurs idiopathically in some large-breed dogs, and patients are usually asymptomatic. Secondary atrial fibrillation is more common and occurs secondary to underlying cardiac disease. *Atrial fibrillation is the heart rhythm described by the "tennis shoes in a dryer" sound in a 7-year-old Doberman with dilated cardiomyopathy. It is characterized by a rapid, irregularly irregular rhythm and commonly occurs in dogs with enlarged atria due to underlying cardiac disease.*

Answer 124

Answer: **Hemangiosarcoma** Explanation The correct answer is hemangiosarcoma. Hemangiosarcoma of the heart has a predilection for the right auricle of dogs, with Golden Retrievers being predisposed. Stabilization of this patient will require pericardiocentesis; prognosis is guarded and may include chemotherapy, pericardiectomy, or rarely auriculectomy. Chemodectoma arises from the ascending aorta and heart base; lymphoma is rare in the heart of dogs and is more commonly metastatic than a single mass. Idiopathic pericardial hemorrhage is incorrect because of the clear evidence of a mass. *The likely diagnosis is hemangiosarcoma. Hemangiosarcoma often affects the right auricle in dogs, with Golden Retrievers being predisposed. Stabilization involves pericardiocentesis; prognosis is guarded and may involve chemotherapy, pericardiectomy, or rarely auriculectomy. Chemodectoma arises from the ascending aorta and heart base. Lymphoma in the heart is rare and typically metastatic. Idiopathic pericardial hemorrhage is excluded due to the evident mass.*

Answer 125

Answer: **Furosemide** Explanation The correct answer is furosemide. Sodium-restricted diets, ACE inhibitors such as enalapril, and diuretics such as furosemide decrease blood volume and preload. ACE inhibitors also reduce afterload by preventing production of angiotensin-ll. a potent vasoconstrictor. Pimobendan is also beneficial in the management of congestive heart failure in the dog due to its positive inotropic effects. Lidocaine is used for treating ventricular arrhythmias. Mirtazapine is an appetite stimulator and not a drug used to treat CHF.

Answer 126

Answer: **Pericardiocentesis** Explanation The correct answer is pericardiocentesis. This radiograph and case are a good example of pericardial effusion with the classic finding of a markedly enlarged heart with a globoid shape. The most common type of effusion by far is hemorrhage which can be idiopathic or from neoplasia such as hemangiosarcoma. Based on this finding, in conjunction with the dog's tachycardia, a pericardial tap for both diagnostic and therapeutic purposes is indicated. Furosemide is contraindicated in cases of pericardial effusion because it will decrease preload in the right side of the heart and can promote circulatory failure. Melarsomine is the treatment for heartworm. Antibiotics are very unlikely to help this dog unless the effusion is from some sort of infectious pericarditis, which would be extremely unusual in dogs. Annotations: Red: The cardiac silhouette is globoid. Yellow: Note the pulmonary metastatic nodules. Green: Concurrent pleural effusion.

Answer 127

Answer: **Mosquito** Dirofilaria immitis or heartworm is the parasite in dogs that resides in the pulmonary artery and can cause congestive heart failure if not recognized and treated. Mosquitoes carrying infective heartworm larvae transmit the infection through bites. The larvae then grow and develop over several months to become sexually mature worms. They then release offspring (microfilariae) into the blood stream.

Answer 128

Answer: **No anti-arrhythmic therapy is necessary at this time** There are several general guidelines/recommendations regarding treatment of ventricular premature contractions which is what is shown on the ECG strip. These include a heart rate of over 180 bpm, pulse deficits, clinical signs, and VPCs for over 20 seconds in duration. In this case, the heart rate is visible on the recording and clearly not elevated. The patient's physical exam findings are not suggestive of an immediate problem secondary to the arrhythmia. There are many dogs with intermittent VPCs that are not of clinical importance. However, it is recommended that the patient be evaluated regularly and ideally have a consultation with a cardiologist to ensure the progression of heart disease is being minimized. Furosemide is not indicated as there is not an indication that the patient is fluid overloaded or in fulminant heart failure. Mexiletine is a Class IB anti-arrhythmic and is not necessary given the lack of severity in the ECG findings. *No anti-arrhythmic therapy is necessary at this time. The ECG shows ventricular premature contractions (VPCs) without clinical signs such as an elevated heart rate over 180 bpm, pulse deficits, or sustained VPCs over 20 seconds. Regular evaluation and cardiologist consultation are recommended to monitor heart disease progression. Furosemide is unnecessary as there's no indication of fluid overload or heart failure. Mexiletine, a Class IB anti-arrhythmic, is also not needed given the mild ECG findings.*

Answer 129

Answer: **Pacemaker implantation** Explanation The correct answer is pacemaker implantation. The rhythm is complete heart block (also known as 3rd degree AV block). There is no consistent PR interval; the ventricular beats are escape beats. Atropine can be considered, but is typically not effective in 3rd degree AV block. The only way to restore a normal heart rate in this patient is by implanting a pacemaker, which will require referral to a cardiologist. Sotalol is a ventricular antiarrhythmic, which would actually be dangerous in this patient because it may suppress the ventricular escape focus. Furosemide and doxycycline will not prove beneficial for this rhythm disturbance. *Pacemaker implantation is the treatment of choice for a 6-year-old Beagle with complete heart block (3rd degree AV block), indicated by a heart rate of 25 bpm and an ECG showing no consistent PR interval with escape beats. Atropine is typically ineffective in 3rd degree AV block. Sotalol, a ventricular antiarrhythmic, could suppress the ventricular escape focus, making it dangerous. Furosemide and doxycycline are not beneficial for this rhythm disturbance.*

Answer 130

Answer: **Mexiletine** Explanation The correct answer is mexiletine. The Holter ECG shows a couplet of ventricular premature complexes. If frequent ventricular ectopy is seen, particularly with runs or R-on-T episodes, treatment is advised with oral ventricular antiarrhythmics. Mexiletine is an oral class I antiarrhythmic that is well-tolerated in dogs. Pimobendan improves systolic function, but does not treat arrhythmias. Amlodipine is a calcium channel blocker used for patients with systemic hypertension. Diltiazem is used for supraventricular tachycardias to slow conduction down the AV node. Furosemide is a diuretic used in the treatment of heart failure, it does not have antiarrhythmic properties. *The correct treatment recommendation for the arrhythmia is mexiletine. The Holter ECG shows a couplet of ventricular premature complexes, and frequent ventricular ectopy, particularly with runs or R-on-T episodes, warrants treatment with oral ventricular antiarrhythmics. Mexiletine, a class I antiarrhythmic, is well-tolerated in dogs. Pimobendan, amlodipine, diltiazem, and furosemide do not address ventricular arrhythmias and serve different cardiac or hypertensive conditions.*

Answer 131

Answer: **Mitral and aortic valves** Explanation The correct answer is mitral and aortic valves. Dogs with endocarditis are most commonly affected on the mitral and aortic valves. The tricuspid and pulmonary valves are rarely affected in dogs and cats, but are the more common sites of infection in large animal species. *The mitral and aortic valves are most commonly affected in dogs with infective endocarditis. In contrast, the tricuspid and pulmonary valves are rarely involved in dogs and cats but are more commonly infected in large animal species. Thus, in a 7-year-old Doberman Pinscher with signs suggestive of endocarditis, focus on the mitral and aortic valves.*

Answer 132

Answer: **Pericardiocentesis** The radiograph and findings are consistent with pericardial effusion. Note the markedly enlarged globoid cardiac silhouette on the DV projection. Pericardiocentesis is necessary for therapeutic and diagnostic purposes. Atenolol and furosemide would be contraindicated. While this dog is showing signs of heart failure, furosemide would decrease preload on the heart and make diastolic filling even worse in cases of pericardial effusion. Atenolol would decrease contractility. This is not a case of heartworm. Radiographic signs of heartworm include right sided cardiac hypertrophy and prominent pulmonary arteries. Taurine levels could be measured in dogs with dilated cardiomyopathy but will take days to get back and this dog needs to be treated immediately. If facilities permit, even a brief echocardiogram could be performed to confirm pericardial effusion and/or to guide the pericardiocentesis. *Pericardiocentesis is the appropriate treatment for a 9-year-old Greyhound with a cough, respiratory difficulty, and a markedly enlarged globoid cardiac silhouette on thoracic radiographs, indicating pericardial effusion. Atenolol and furosemide are contraindicated as they would worsen diastolic filling and decrease contractility, respectively. Heartworm test and taurine level measurement are unnecessary in this immediate context. An echocardiogram can confirm the diagnosis and guide pericardiocentesis.*

Answer 133

Answer: **Myxomatous mitral valve degeneration** Explanation The correct answer is myxomatous mitral valve degeneration. This disease is the most common cardiac disease in veterinary medicine and affects up to 60% of dogs older than 8 years of age. It commonly occurs in small breed dogs and can clinically range from having only a soft murmur to being in congestive heart failure. It is caused by degeneration and accumulation of acid-staining mucopolysaccharides in the cardiac valves and most commonly affects the mitral valve. A dog with bacterial endocarditis would show signs of systemic illness such as fever and lethargy. Congenital mitral dysplasia would usually result in more marked cardiac changes (louder murmur, more regurgitation, dilated heart chambers) at a much earlier age. Systolic anterior motion or SAM of the mitral valve occurs with hypertrophic cardiomyopathy as one of the leaflets of the mitral valve obstructs the left ventricular outflow tract as the chamber contracts. *The most likely cause of mitral regurgitation in this 11-year-old Shih Tzu is myxomatous mitral valve degeneration. This common cardiac disease in dogs over 8 years old, especially small breeds, ranges from a soft murmur to congestive heart failure. It involves degeneration and mucopolysaccharide accumulation in the mitral valve. Bacterial endocarditis, congenital mitral dysplasia, and systolic anterior motion are less likely due to their distinct presentations and associated symptoms.*

Answer 134

Answer: **Provide a lidocaine bolus followed by a continuous infusion of lidocaine** Explanation This patient is exhibiting premature ventricular contractions which is commonly observed after splenectomy. Any patient that has a splenectomy should be monitored closely for that reason. Most of the time these are not severe enough to require treatment. There are some general guidelines for when to treat VPCs which include excessive pulse deficits, the patient is clinically affected, a heart rate greater than 180 bpm, or greater than 20 second stretch of continuous VPCs. In this case it is important to know that the patient was just given a dose of post-operative pain medication (at an appropriate dose) which rules out an elevated heart rate secondary to pain. The patient is anemic, but he is not anemic to the point of requiring an emergency transfusion. Transfusions are usually not administered unless there is expected ongoing blood loss (which is not the case) or the PCV is less than 20. Lidocaine is an anti-arrhythmic and is typically the drug of choice for treatment of VPCs. A bolus is administered first to determine if the rhythm is responsive to lidocaine and then a CRI is initiated at 20-80 micrograms per kilogram per minute. *The best treatment option is to provide a lidocaine bolus followed by a continuous infusion of lidocaine. This Golden Retriever is experiencing premature ventricular contractions (VPCs), common after splenectomy. Lidocaine, an anti-arrhythmic, is the drug of choice for VPCs, especially when the heart rate exceeds 180 bpm. Although the patient is anemic, the PCV level does not indicate the need for an emergency transfusion, and the recent hydromorphone dose rules out pain as the cause of the elevated heart rate.* **Antiarrhythmics for Use in Animals: Comprehensive Overview** Definitions and Classes of Antiarrhythmics • Antiarrhythmics: Drugs used to treat abnormal heart rhythms. • Classes: Based on the Vaughan Williams classification. • Class I: Sodium channel blockers. • Class II: Beta-blockers. • Class III: Potassium channel blockers. • Class IV: Calcium channel blockers. Class I: Sodium Channel Blockers • Examples: Quinidine, Procainamide, Lidocaine. • Mechanism: Inhibit sodium influx, reducing excitability and conduction. • Uses: Atrial and ventricular arrhythmias. Class II: Beta-Blockers • Examples: Propranolol, Atenolol. • Mechanism: Block beta-adrenergic receptors, reducing heart rate and contractility. • Uses: Supraventricular and ventricular tachyarrhythmias. Class III: Potassium Channel Blockers • Examples: Amiodarone, Sotalol. • Mechanism: Prolong repolarization by inhibiting potassium channels. • Uses: Atrial fibrillation, ventricular tachycardia. Class IV: Calcium Channel Blockers • Examples: Verapamil, Diltiazem. • Mechanism: Inhibit calcium influx, reducing conduction through the AV node. • Uses: Supraventricular tachyarrhythmias. Indications and Contraindications • Indications: Based on specific arrhythmias. • Contraindications: Vary per drug class and individual drug profiles. Monitoring and Side Effects • Monitoring: ECG, blood pressure, and heart rate. • Side Effects: Hypotension, bradycardia, gastrointestinal disturbances, hepatotoxicity. Diagnostics • ECG: Essential for diagnosing type and severity of arrhythmia. • Holter Monitoring: For intermittent arrhythmias. Treatment Protocols • Acute Management: IV administration in emergency situations. • Chronic Management: Oral medications for long-term control. Summary Points for BCSE Test • Understand Drug Classes: Mechanisms, examples, and uses. • Monitoring and Side Effects: Critical for safe administration. • Diagnostics: ECG and Holter monitoring. • Treatment Protocols: Acute vs. chronic management.

Answer 135

Answer: **Balloon valvuloplasty** Explanation The correct answer is balloon valvuloplasty. This procedure is performed by inserting a catheter into either a jugular vein or a femoral vein and advancing it into the region of stenosis at the pulmonic outflow tract. Once in place, a balloon surrounding the catheter is inflated to stretch the stenotic region open. Surgical valvulotomy or patch grafting is the treatment used for severe cases that cannot be balloon-dilated. *The treatment of choice for pulmonic stenosis in dogs is balloon valvuloplasty. This procedure involves inserting a catheter into a vein and inflating a balloon at the stenotic pulmonic outflow tract to widen the narrowed area. Surgical valvulotomy or patch grafting is reserved for severe cases not responsive to balloon dilation.*

Answer 136

Answer: **Immiticide (Melarsomine)** Explanation The correct answer is Immiticide (melarsomine). The dog in this radiograph has the classic findings for heartworm disease, including right sided ventricular enlargement with very prominent pulmonary arteries. Heartworm in the dog is caused by Dirofilaria immitis. The treatment of choice for heartworm is Immiticide which is given by intramuscular injection. Furosemide is a treatment for congestive heart failure, which this dog shows no evidence of. Terbutaline is a bronchodilator, which would be of little use in this case. Broad-spectrum antibiotics are useful for the treatment of pneumonia and other infections but are not effective against heartworm. Pericardiocentesis is obviously the treatment for pericardial effusion, but this dog's radiographs do not show the classic globoid heart you might see with pericardial effusion. Annotations: Green arrow: apex of the heart shifted towards the left hemithorax indicative of right cardiac enlargement Blue: right sided cardiac enlargement of right atrium and right ventricle Yellow: Severely enlarged main pulmonary artery Red: pulmonary arteries are enlarged and mildly tortuous. All the changes are indicative of pulmonary hypertension secondary to heartworm disease. Throughout the lungs there is a moderate diffuse bronchointerstial pattern throughout, most suggestive of eosinophilic pneumonitis. Radiographs provided by Adrien Hespel, DVM, MS, DACVR and University of Tennessee College of Veterinary Medicine. *** PowerPage: Heartworm disease *The treatment of choice for this case is Immiticide (melarsomine). The dog’s radiographs and clinical findings, including right ventricular enlargement and prominent pulmonary arteries, are indicative of heartworm disease caused by *Dirofilaria immitis*. Immiticide is administered via intramuscular injection to treat heartworm. Other treatments, such as furosemide, terbutaline, antibiotics, or pericardiocentesis, are not appropriate for this diagnosis, as they address different conditions.* **Heartworm disease in dogs, cats, and ferrets. Comprehensive list of key points relevant for the NAVLE:** General Information: • Causative Agent: Dirofilaria immitis (filarial nematode). • Vector: Mosquitoes (e.g., Aedes, Anopheles, Culex). • Species Affected: Primarily dogs, but also cats, ferrets, and occasionally other species like coyotes and foxes. Pathogenesis: • Life Cycle: Mosquitoes transmit infective larvae (L3), which migrate into the host, molt, and mature into adults in the pulmonary arteries. • Pulmonary Disease: The disease affects the pulmonary arteries, causing inflammation, endarteritis, and pulmonary hypertension. Long-term infections can lead to chronic lesions, scarring, and heart failure. • Immunological Response: Wolbachia bacteria within the heartworms contribute to the inflammatory response and disease severity. Antigenic stimulation leads to immune responses, causing further damage. Clinical Findings: • Dogs: Most common signs include cough, exercise intolerance, and signs of right-sided heart failure (e.g., ascites). Severe cases can lead to caval syndrome with signs like hemolysis, anemia, and hepatorenal dysfunction. • Cats and Ferrets: Often subclinical or mild, but severe cases can present with respiratory distress, weight loss, lethargy, vomiting, and sudden death. Cats can suffer from HARD (heartworm-associated respiratory disease). Diagnosis: • Serology: Antigen testing is the primary method in dogs, while antibody testing is more useful in cats due to the lower sensitivity of antigen tests in cats. • Microfilaria Detection: Direct smear or modified Knott test; useful as an adjunct in dogs. • Imaging: Thoracic radiography, echocardiography (particularly important in cats and ferrets). Treatment: • Dogs: Adulticide therapy with melarsomine (an organic arsenic compound), typically in a three-dose protocol. Adjunct therapy with doxycycline to target Wolbachia. Supportive care and exercise restriction are crucial. • Cats and Ferrets: No safe adulticide therapy; treatment focuses on managing symptoms with corticosteroids, oxygen therapy, and occasionally surgical removal of heartworms. Prevention: • Macrocyclic Lactones: Regular administration of ivermectin, milbemycin, selamectin, or moxidectin for prevention. For dogs, these drugs also serve as microfilaricides. Stages of Disease: 1. Stage I: Subclinical or minimal signs. 2. Stage II: Mild to moderate signs, typically including cough. 3. Stage III: Severe signs, such as weight loss, respiratory distress, and right heart failure. 4. Stage IV: Caval syndrome with severe cardiopulmonary compromise.

Answer 137

Answer: **Arterial oxygen pressure is 60 mm Hg, and oxygen saturation may drop precipitously if it decreases further** Explanation When assessing an anesthetized patient with pulse oximetry, it is important to realize several things: The shape of the oxygen saturation curve is sigmoid, and until you reach oxygen pressures of ‹ 60 mm Hg, there is very little change in oxygen saturation. Because an anesthetized patient breathing 100% oxygen should have about 500 mm Hg oxygen in the arterial blood, this can drop a long way before a dramatic change to oxygen saturation occurs. However, the time to intervene is early when you see saturation percentages decrease because it means that your patient is oxygenating very poorly, especially if they are breathing 100% oxygen, and even a relatively small further decline could dramatically reduce their oxygen saturation, resulting in tissue hypoxia and dangerous consequences. - An oxygen saturation of 98-100% corresponds to > 100 mm Hg oxygen in arterial blood - An oxygen saturation of 95% corresponds to 80 mm Hg An oxygen saturation of 90% corresponds to 60 mm Hg - An oxygen saturation of 50% corresponds to 30 mm Hg - An oxygen saturation of 10% corresponds to 10 mm Hg By the way, in room air, arterial oxygen pressure should normally be 80-100 mm Hg and oxygen saturation is 95-100% *The patient's oxygen saturation of 90% indicates that the arterial oxygen pressure is approximately 60 mm Hg. This is concerning because further decreases could result in a rapid and dangerous drop in oxygen saturation, potentially leading to tissue hypoxia. Since the patient is under anesthesia and likely breathing 100% oxygen, this saturation level is lower than expected and warrants immediate attention to prevent serious complications.*

Answer 138

Answer: **Supraventricular tachycardias may progress to atrial fibrillation and cause progressive left ventricular dysfunction, whereas ventricular tachycardias may lead to ventricular fibrillation and death.** Explanation Supraventricular tachycardia can lead to atrial fibrillation, which is not life threatening. With atrial fibrillation, the atrial depolarization rate in a dog is usually from 400-700/minute. Usually, about one third of depolarizations get through the AV node to the ventricles to cause a ventricular contraction. Rapid supraventricular arrhythmias can wear out the LV myocardium causing LV dysfunction. Ventricular tachycardias, however, can cause electrical instability and progress to ventricular fibrillation, which leads to cardiovascular collapse and death if not rapidly converted back to a normal rhythm. *Supraventricular tachycardias are less clinically important than ventricular tachycardias because, while supraventricular tachycardias can lead to atrial fibrillation and progressive left ventricular dysfunction, they are generally not life-threatening. Ventricular tachycardias, however, can cause severe electrical instability, potentially progressing to ventricular fibrillation, which can result in cardiovascular collapse and death if not treated promptly.*

Answer 139

Answer: **Heartworm antigen test** Based on the radiograph, you should be concerned about the likelihood of heartworm disease. On the V/D projection, the heart shape is a reverse D, indicative of right sided heart enlargement. There is enlargement of the caudal pulmonary arteries and a caudodorsal pulmonary interstitial pattern. There is no evidence of right heart failure in the films, but these changes are suggestive of heartworm. The antigen test is a sensitive test for this disease in dogs. Serum lead levels are not important as the dog has no signs of lead toxicity. A fecal flotation would be a good idea in this dog with an eosinophilia, but given the radiographic findings, heartworm is a much more important condition to identify and rule out as a cause first. A TLI is the test for exocrine pancreatic insufficiency. This dog is underweight, but this is likely due to previous neglect. If he does not gain weight now that he has a good home, you should investigate. A serum electrophoresis would be a test to evaluate for a monoclonal gammopathy. The hyperglobulinemia in this case is much more likely due to heartworm and the chronic antigenic stimulation than an immunoglobulin-secreting cancer. A urine cortisol:creatinine ratio to screen for hyperadrenocorticism is not indicated in this patient. Annotations: - green arrow: apex of the heart shifted towards the left hemithorax indicative of right cardiac enlargement - Blue: right sided cardiac enlargement RA and RV - Right:Left caudal pulmonary artery is enlarged and mildly tortuous. All the changes are indicative of pulmonary hypertension, most commonly HW Left: Pulmonary artery of the left cranial is also enlarged and mildly tortuous Radiographs provided by Adrien Hespel, DVM, MS, DACVR and University of Tennessee College of Veterinary Medicine *The most important additional diagnostic test to recommend is a heartworm antigen test. The thoracic radiographs show a reverse D-shaped heart, indicative of right-sided heart enlargement, along with enlarged and tortuous pulmonary arteries, suggesting pulmonary hypertension commonly seen with heartworm disease. While eosinophilia warrants consideration of fecal flotation, heartworm testing takes priority due to the radiographic findings. Other tests, such as TLI or serum lead levels, are less relevant for this case.*

Answer 140

Answer: **7-10 days** The correct answer is 7-10 days. *Canine parvovirus* mainly affects puppies and young dogs less than a year of age. Transmission of the virus is through contact with infected feces and fomites such as hands, toys, the dog's hair coat. The virus is very resilient in the environment and is resistant to many types of disinfectants. It replicates in the crypt epithelium of the gut and causes epithelial necrosis and hemorrhagic diarrhea. The virus can also affect the heart of young puppies, causing myocarditis. This occurs less commonly now since most bitches are immunized against the virus, which allows for maternal antibodies to protect young puppies from this form of the disease.

Answer 141

Answer: **Iron deficiency** Explanation The correct answer is iron deficiency. The CBC shows a microcytic, hypochromic, non-regenerative anemia. Reticulocyte counts under 60,000/ul are typically considered non-regenerative in most labs. This is consistent with chronic iron deficiency. This most common reason for chronic blood loss is gastrointestinal tract disease such as an ulcer or cancerous lesion.

Answer 142

Answer: **Halfway between the greater and lesser curvature of the stomach** Explanation The correct answer is halfway between the greater and lesser curvature. At this site, you avoid any major bleeding and retain good blood supply from both sides to help with the healing of your incision. Cutting along the greater and lesser curvature is not recommended due to the need to avoid blood vessels. Cutting along the pylorus has a risk of disturbing the sphincter and causing the formation of a pyloric stricture. Additionally, this does not provide a good view inside the stomach. ***PowerLecture: Surgery Of The Stomach

Answer 143

Answer: **The lymph node aspirate results are a negative prognostic indicator** Explanation You should never find sheets of epithelial cells in a lymph node unless it is infiltrated with metastasis (or unless you aspirated something else on accident, like a salivary gland). Metastasis of mammary gland tumors in dogs is a negative prognostic indicator, whereas none of the other choices above are thought to directly influence prognosis.

Answer 144

Answer: **At least 20 mg/dl less than the blood glucose** Explanation The correct answer is at least 20 mg/dL less than the blood glucose. The image depicts a perforated colon, which will result in a septic abdomen due to the normal colonic flora emptying into the abdomen. A concentration difference > 20 mg/dL between blood and peritoneal fluid glucose concentration provides a rapid and reliable means to differentiate a septic peritoneal effusion from a nonseptic peritoneal effusion in dogs and cats.

Answer 145

Answer: **Fecal float** Explanation Hookworms (Ancylostoma and Uncinaria) are intestinal parasites that suck blood and can cause anemia, enteritis, coughing during larval migration, and dermatitis. Any young dog that is failing to thrive and/or has pale mucous membranes should be tested for intestinal parasites. Hookworm dermatitis, also called Ancylostomiasis is typically seen in conditions with poor sanitation and/or in kennels. Hookworms can be transmitted in utero, during nursing, or via 3rd stage larva penetrating the skin. The most commonly affected skin areas are the pads and interdigital spaces of the feet, but can include any surface that contacts the ground. The larva migrate through the dog's tissues before arriving in the intestines. They cause significant anemia, failure to thrive, or sudden death in young dogs. In mild cases, deworming protocols are often enough; with severe cases blood transfusions and parenteral treatments are often necessary. Skin scraping and impression smears of the affected skin areas are typically unrewarding for isolating parasites. A PCV/TP would show signs of anemia, but not the underlying etiology. Complete blood cell count and chemistry will often show anemia that is regenerative and an eosinophilia. Radiographs would be unrewarding in this case. A biopsy may show migrating larva if biopsied soon after trauma, however this is not a diagnostic test routinely used **Hookworms in Small Animals - Comprehensive Veterinary Information** Definitions and Terminology: • Hookworms: Intestinal nematodes, primarily affecting dogs and cats, leading to significant health issues. Causative Agents: • Species: • Ancylostoma caninum (dogs) • Ancylostoma tubaeforme (cats) • Ancylostoma braziliense (dogs and cats) • Ancylostoma ceylanicum (dogs and cats) • Uncinaria stenocephala (dogs and cats in cooler regions) Physiopathology: • Life Cycle: Eggs pass in feces, hatch in soil, and larvae infect hosts through ingestion, skin penetration, or transmammary routes. • Larval Migration: Skin penetration, blood to lungs, coughed up, swallowed, mature in intestines. Arrested larvae in tissues can reactivate. Clinical Findings: • Acute Anemia: Normocytic, normochromic progressing to hypochromic, microcytic in puppies. • Chronic Infections: Anemia, melena, hypoproteinemia, weakness, diarrhea. • Lesions: Hemorrhagic enteritis, pneumonia in pups, dermatitis (interdigital spaces). Diagnosis: • Fecal Flotation: Detects thin-shelled, oval eggs. • Antigen Tests: For hookworm detection. • Postmortem: Examination of intestines for adult worms. Treatment: • Anthelmintics: • Fenbendazole • Moxidectin • Pyrantel pamoate • Milbemycin • Nitroscanate • Supportive Care: Blood transfusions, iron supplements, high-protein diet for severe anemia. • Drug Resistance: Monitor efficacy post-treatment, especially in A. caninum cases. Control and Prevention: • Regular Deworming: Based on age and risk factors. • Sanitation: Dispose of feces promptly, maintain clean environments. • Preventive Measures: Treat pregnant bitches, routine fecal checks. Key Points: • Zoonotic Potential: A. braziliense and A. ceylanicum can infect humans. • Drug Resistance: Emerging problem, particularly in the southeastern US.

Answer 146

Answer: **PU/PD** Explanation The answer is polyuria and polydipsia. Estrogen secreting Sertoli cell tumors are quite common in cryptorchid testes and cause the clinical signs of truncal alopecia, hyperpigmentation, gynecomastia, urinating in a female position, and bone marrow dyscrasias such as aplastic anemia. Attraction of other males can also occur. PU/PD is a sign commonly seen with endocrinopathies but not this one.

Answer 147

Answer: **Elevated liver enzymes** Explanation Ketoconazole is hepatotoxic and can cause elevated liver enzymes. It is a potent inhibitor of P450 enzymes and can significantly affect metabolism of other drugs. It can cause adrenal insufficiency and actually is sometimes used as an alternative treatment for Cushing's. Anorexia is a common and important side effect, especially in cats. The kidneys and GFR are not significantly bothered by ketoconazole. Facial excoriation is a potential side effect of methimazole, not ketoconazole.

Answer 148

Answer: **Antihistamines, corticosteroids, and epinephrine** Explanation The dog has angioedema +/- anaphylaxis, likely caused by an insect bite or sting. A snake bite should also be ruled out by trying to visualize the bite or questioning the owners. This is a type I hypersensitivity reaction and is treated by removing the offending agent if possible and providing supportive care with anthistamines, corticosteroids, and epinephrine as needed.

Answer 149

Answer: **Mast cell tumors** Explanation The correct answer is mast cell tumors. Many of the clinical signs of mast cell tumors are related to the factors released by mast cells including histamine, heparin, and other vasoactive amines. Histamine can cause ulcers via activation of H2 receptors on gastric parietal cells. Heparin can cause coagulopathy. Histamine and other vasoactive amines can lead to vasodilation and hypotension.

Answer 150

Answer: **Mast cell tumors** Explanation The correct answer is mast cell tumors. Many of the clinical signs of mast cell tumors are related to the factors released by mast cells including histamine, heparin, and other vasoactive amines. Histamine can cause ulcers via activation of H2 receptors on gastric parietal cells. Heparin can cause coagulopathy. Histamine and other vasoactive amines can lead to vasodilation and hypotension.

Answer 151

Answer: **Weight loss, controlled leash walks, omega-3 fatty acid supplementation** Explanation Given that Manny is lame after intense exercise and is an older, overweight, large-breed dog, he is probably dealing with degenerative joint disease (DJD). It is not uncommon for owners to decline diagnostics when they just think their dog is getting old. Unfortunately this makes treating the patient appropriately a bit more difficult. Ideally you would like to rule out evidence of a primary bone tumor, cruciate ligament tear, and see evidence of DJD on a radiograph. In certain regions of the country Lyme disease is a common cause of lameness, and a simple blood test can screen for exposure to this disease. Prior to starting Manny on long-term medications, you would recommend blood work to make sure there are no underlying diseases that could be worsened from medications like NSAIDs. Management of DJD or osteoarthritis consists of weight management, controlled exercise, and neutraceuticals that decrease inflammation such as glucosamine/chondroitin, Omega-3 fatty acid supplementation or diets that contain these nutrients. Some patients will show dramatic improvements with these simple changes, saving the pain medications for later. Physical therapy and swimming can also be helpful to strengthen the muscles, but punishing activities like sprinting, jumping and rough play should be avoided.

Answer 152

Answer: **Cutaneous histiocytoma** Explanation The correct answer is cutaneous histiocytoma. Cutaneous histiocytomas in dogs occurs early in life at less than 3 years of age. The lesions are alopecic, raised, nodules that often ulcerate and regress on their own. Treatment is not needed unless the lesions persist. Treatment for persistent lesions is surgery. The other tumor types do not regress, although mast cell tumors may grow and shrink over time.

Answer 153

Answer: **Immunosuppressive doses of glucocorticoids** Explanation This is a classic clinical presentation for juvenile cellulitis (puppy strangles). This disease is characterized by sterile granulomas and pustules that respond dramatically to glucocorticoids. The cause is thought to be an underlying immune dysfunction. Immunosuppressive glucocorticoid therapy should not be started until other infectious diseases have been ruled out. At a minimum a deep skin scrape, skin cytology, and trichogram should be performed to rule out Demodex, bacteria, and fungal infection.

Answer 154

Answer: **Owner is not applying the product properly, owner is not treating the environment, and other pets in the household are not on flea control** Explanation This question is a review of the most common reasons for failure of a flea product to work. Education is extremely important when starting flea treatment. Always question how the owner applies the product, whether the environment is being treated, and make sure all pets in the household are undergoing treatment. One is often surprised how many owners apply topical products just to the hair of their animals. Many owners (and veterinarians) blame lack of response to resistance against flea adulticides; however, it is much more likely (in the majority of cases) that it is due to one of these 3 listed reasons. PowerPage: Flea Allergy Dermatitis

Answer 155

Answer: **Immunofluorescent assay on affected epithelium** Explanation The correct answer is *immunofluorescent assay* on affected epithelium. Although the clinical signs are supportive for distemper, the definitive diagnosis is examination of blood or tissue by immunofluorescent assay. This can be performed on tracheal, vaginal, respiratory, or other epithelium. These samples may be negative if the dog is only showing neurologic signs or if a circulating antibody is present. The diagnosis can then be made by serology for distemper IgM or increased CSF to serum virus specific IgG. In addition, a distemper PCR test is now available and is performed on swabs of ocular or nasal discharge. The test can have false positives in some vaccinated animals; however, animals showing signs consistent with distemper that are PCR positive should be considered likely infected with distemper.

Answer 156

Answer: **The lesion should resolve with topical antibiotic treatment** Explanation Most acral lick lesions are solitary and affect the carpus or metacarpus. About 50% will be diagnosed as idiopathic or psychogenic, but other diseases must be ruled out first including bacteria, fungal, demodicosis, trauma, allergy, and underlying joint disease. A full work-up may include skin cytology, fungal culture, biopsy, diet trial, skin testing, radiographs of the joint, and addressing behavioral disorders. Most of these lesions will have a deep bacterial infection and treatment should include systemic antibiotics based on a deep culture sample. Topical antibiotics may not penetrate the area well enough to resolve the infection. Management also includes treating the underlying cause. Many veterinarians will also prescribe topical or intralesional steroids. If no cause is found, then antidepressants or anxiolytics may be started. These lesions will rarely go away unless the underlying cause is identified and properly treated.

Answer 157

Answer: **Periodontal ligament** Explanation The periodontal ligament is made of collagen fibers and creates a strong connection between the root of the tooth and the alveolar bone. It can be extremely difficult to breakdown during a healthy tooth extraction, as in the case of a complicated crown root fracture.

Answer 158

Answer: **Peritoneopericardial diaphragmatic hernia** Explanation The answer is peritoneopericardial diaphragmatic hernia. Pleuroperitoneal diaphragmatic hernias or what most of us think of as regular diaphragmatic hernias can be congenital or traumatic in origin. Trauma can cause an abrupt increase in intra-abdominal pressure forcing the lungs to rapidly deflate causing a large pleuroperitoneal pressure gradient. This pressure gradient can cause the diaphragm to tear at its weakest point, typically the muscular portions. Peritoneopericardial hernias are always congenital in dogs and cats (interestingly, they can be caused by trauma in humans). Hopefully, rib fractures and pulmonary contusions were obvious. ***PowerPage: Thoracic Trauma

Answer 159

Answer: **You are concerned about a vaccine reaction; biopsy** Explanation The lesion is highly suggestive of a vaccine reaction; particularly post-rabies vaccination panniculitis (inflammation of the sub-cutaneous) due to location and description of the lesion. Rabies vaccine is often given in the right hind limb. Initially, this condition presents with a nodule where the vaccine occurred and then complete alopecia occurs 1-3 months afterward. Many times there is a long delay between vaccination and clinical signs (up to 6 months). Lesions usually resolve on their own, but use of pentoxifylline or prednisone can be effective. Definitive diagnosis would require a skin biopsy. An allergic reaction or endocrinopathy is less likely since the lesion is focal. Endocrinopathies usually result in bilaterally symmetrical alopecia. Hair loss due to allergies is usually a result of pruritus, which was not mentioned in the patient's history. This would be an atypical location and lesion for an autoimmune condition.

Answer 160

Answer: **Central diabetes insipidus** Explanation The correct answer is central diabetes insipidus. Diabetes mellitus is ruled out with a normal blood glucose on the chemistry panel and lack of glucose in the urine on the urinalysis. Chronic renal failure is ruled out because there is no azotemia on the chemistry panel. Fanconi syndrome usually occurs in Basenjis and is ruled out because there is no glucose in the urine. ***PowerPage: Polyuria and Polydipsia

Answer 161

Answer: **Ancylostoma** Explanation The correct answer is Ancylostoma. These are hookworms; when they come in contact with unprotected skin, the infective larvae penetrate the epidermis but generally cannot penetrate the basement membrane. They therefore migrate aimlessly, and the disease is usually self-limiting in humans.

Answer 162

Answer: **Prednisone** Explanation This is a case of lymphoma. The cytology depicts the classic finding of a population of lymphoid cells that are predominantly lymphoblasts based on their size and characteristics. If you were unsure about their size due to magnification, there is a neutrophil in the lower left corner for comparison. The lymphoblasts are considerably larger than the neutrophil. Mature lymphocytes would be smaller than a neutrophil. Note that there is a mitotic figure in the middle of the slide. There are many treatments and protocols for lymphoma and some of the main agents known to have efficacy are prednisone, doxorubicin, cyclophosphamide, vincristine, L-asparaginase, and lomustine. There are many other efficacious chemotherapeutics for lymphoma but carboplatin is not considered a first line treatment for lymphoma in dogs. The other drugs listed are antifungal (itraconazole), antibiotic (doxycycline) and anti-parasitic (milbemycin).

Answer 163

Answer: **Prednisone** Explanation This is a case of lymphoma. The cytology depicts the classic finding of a population of lymphoid cells that are predominantly lymphoblasts based on their size and characteristics. If you were unsure about their size due to magnification, there is a neutrophil in the lower left corner for comparison. The lymphoblasts are considerably larger than the neutrophil. Mature lymphocytes would be smaller than a neutrophil. Note that there is a mitotic figure in the middle of the slide. There are many treatments and protocols for lymphoma and some of the main agents known to have efficacy are prednisone, doxorubicin, cyclophosphamide, vincristine, L-asparaginase, and lomustine. There are many other efficacious chemotherapeutics for lymphoma but carboplatin is not considered a first line treatment for lymphoma in dogs. The other drugs listed are antifungal (itraconazole), antibiotic (doxycycline) and anti-parasitic (milbemycin).

Answer 164

Answer: **Donor red blood cells, recipient plasma** Explanation The correct answer is donor red blood cells, recipient plasma. In a major crossmatch, you are looking to see if the factors in the plasma of the recipient are going to react to the donated red blood cells. A minor crossmatch involves recipient red blood cells and donor plasma.

Answer 165

Answer: **Donor red blood cells, recipient plasma** Explanation The correct answer is donor red blood cells, recipient plasma. In a major crossmatch, you are looking to see if the factors in the plasma of the recipient are going to react to the donated red blood cells. A minor crossmatch involves recipient red blood cells and donor plasma.

Answer 166

Answer: **Uveal cyst** Explanation The correct answer is uveal cyst. This description is most consistent with a uveal cyst and not a melanoma because it is free-floating. It is often difficult to distinguish these two conditions because cysts can also be attached to the pupillary margin or posterior iris. The other way to try to distinguish the two is with transillumination. Melanomas will not transilluminate while many cysts will. Also, cysts are usually very spherical or ovoid and smooth while melanomas are usually fleshier-appearing masses.

Answer 167

Answer: **Uveal cyst** Explanation The correct answer is uveal cyst. This description is most consistent with a uveal cyst and not a melanoma because it is free-floating. It is often difficult to distinguish these two conditions because cysts can also be attached to the pupillary margin or posterior iris. The other way to try to distinguish the two is with transillumination. Melanomas will not transilluminate while many cysts will. Also, cysts are usually very spherical or ovoid and smooth while melanomas are usually fleshier-appearing masses.

Answer 168

Answer: **It can cause esophageal stricture formation if the drug remains in the esophagus for an extended time** Explanation Doxycycline is a tetracycline antibiotic that can cause esophageal stricture formation if it remains in the esophagus for an extended period of time. A small amount of food or water is usually given after the pill to ensure the tablet is not lodged in the esophagus. It can also cause teeth abnormalities in growing animals and often causes Gl upset. It is not an anti-fungal and is not used to treat inflammatory bowel disease. Fluoroquinolone antibiotics such as enrofloxacin can cause cartilage formation abnormalities in growing animals.

Answer 169

Answer: **Indistinct lesion margins** Explanation The correct answer is indistinct lesion margins. The radiographic characteristics of an aggressive bone lesion are poorly-defined transition zones between normal and abnormal bone, moth-eaten appearance to the bone, and active periosteal reaction, especially heterogeneous reaction. The other answer choices in this question are characteristics of nonaggressive bone lesions.

Answer 170

Answer: **Rabies** Explanation The correct answer is rabies. If it sounds like it could be rabies, diagnose it until proven otherwise. The signs to focus on are attacked by a wild animal, a behavior change, and a voice change. This should put rabies at the top of your list. This dog is exhibiting signs of the prodromal stage of rabies. Canine distemper is a potential differential, but you will most likely see other symptoms such as respiratory and Gl signs. Tetanus will manifest itself as rigidity and botulism as flaccid paralysis. Remember that any animal with an acute behavioral change or flaccid paralysis is a rabies suspect.

Answer 171

Answer: **Correction of acidosis, electrolyte abnormalities, and hyperosmolality** Explanation The correct answer is correction of acidosis, electrolyte abnormalities, and hyperosmolality. Initial treatment of DKA patients is aimed at correcting acidosis by administering bicarbonate (if the total bicarbonate is markedly low), correcting electrolyte abnormalities with IV fluids, potassium and phosphorus supplementation, and correction of hyperosmolality. Regulating blood glucose, getting the animal to eat, controlling obesity and concurrent disease should be addressed after immediate life-threatening issues are resolved.

Answer 172

Answer: **Via tick vector** Explanation This is a case of Babesia gibsoni. Babesia sp. are protozoa that parasitize erythrocytes, causing anemia. Many different species exist. B. cans and B. gibsoni are two organisms commonly known to infect dogs, both organisms have Ixodid tick vectors. Babesia gibsoni, as seen here, is a small ring shaped parasite. Bites from other dogs during dog fights is also thought to be an important mode of transmission, possibly explaining the increased incidence of the disease in pit bulls and staffordshire terriers.

Answer 173

Answer: **Before the first estrus** Explanation Development of mammary tumors in the dog is hormone-dependent. As such, ovariohysterectomy before a heat cycle prevents the hormonal effects on the mammary glands that predispose them to developing tumors. Dogs spayed prior to an estrus are 0.05% times as likely to develop a mammary tumor as an intact dog. That risk rises to 8% and 26% after one and two heats respectively with no decrease in risk if they are spayed subsequent to a third heat.

Answer 174

Answer: **Surgical exploratory laparotomy** Explanation This dog has a septic abdomen and requires surgical intervention. Sepsis is suspected if the glucose in the ascites is at least 20mg/dL less than the peripheral blood. A blood lactate level of 2.0mmol/L lower than the ascites lactate level is also highly suggestive of a septic abdomen. The presence of intracellular bacteria would also be diagnostic for a septic abdomen. The hypotension, bradycardia, and hypothermia can be attributed to the sepsis as well. An abdominal ultrasound may help to determine the source. Rehydration and antibiotics are necessary components of treatment but ultimately surgical exploration is necessary.

Answer 175

Answer: **Regenerative anemia** Explanation The correct answer is regenerative anemia. Spherocytes, autoagglutination, and positive Coombs are all specific for IMHA, but a regenerative anemia could be seen in either instance.

Answer 176

Answer: **Struvite** Explanation The correct answer is struvite. Struvite or magnesium ammonium phosphate crystals form in alkaline urine, whereas most other crystal types form in acidic urine. The cocci present are urease positive bacteria that cleave urea to ammonia causing the urine pH to rise and making the environment more favorable for struvite crystals to form. Cysteine crystals form as a result of a genetic defect of the renal tubules, and are almost exclusively seen only in males. Urate crystals only form in Dalmatians (due to a genetic defect in urate metabolism) and animals with portosystemic shunts or liver dysfunction. Urates are less likely in this patient, since it is not a Dalmatian and shows no signs of liver disease. ***PowerPage: Urolithiasis

Answer 177

Answer: **Pre- and post-prandial bile acids** Explanation Based on the breed and young age of the animal with these neurologic signs and ammonium biurate crystalluria, a portosystemic shunt should immediately be your top differential. A pre- and post-prandial bile acid test assesses hepatic function. The enterohepatic circulation is highly effective in normal animals but not animals with shunts. Bile salts excreted in bile return to the liver by intestinal absorption and portal blood. High pre- and post-prandial bile acids indicate a decrease in hepatic function. In congenital and acquired portal systemic shunts, bile acids are allowed to bypass the liver and enter systemic blood. This results in markedly elevated post-prandial bile acid levels. ALT is a liver specific leakage enzyme; however, it does not reflect liver function. ALT may be within reference intervals in animals with decreased hepatic mass. AST is also a hepatocyte leakage enzyme but does not reflect liver function. It is not as liver-specific and is found in erythrocytes and cardiac and skeletal muscles. The animal's neurologic signs are likely from hepatic encephalopathy from a portosystemic shunt so an MRI would not confirm your diagnosis. TLI is the test of choice to diagnose exocrine pancreatic insufficiency. ***PowerPage: Portosystemic Shunt ***PowerLecture: Portosystemic Shunts

Answer 178

Answer: **Hookworms** Explanation The correct answer is hookworms. When Ancylostoma comes in contact with unprotected skin, the infective larvae penetrate the epidermis but generally cannot penetrate the basement membrane. They therefore migrate aimlessly, and the disease is usually self-limiting in humans.

Answer 179

Answer: **Oxytetracycline** Explanation The correct answer is oxytetracycline. Salmon poisoning commonly occurs in the Pacific Northwest (Washington, Oregon, Northern California, and southern Vancouver Island in Canada). Dogs contract the disease by ingesting raw fish containing the fluke Nanophyetus salmincola which carries the rickettsial organism Neorickettsia helminthoeca. The most common vector is raw salmon, hence the name. Other cases have occurred from the ingestion of freshwater trout and salamanders. Clinical signs include fever, vomiting, diarrhea, enlarged lymph nodes, and depression. Rare cases can develop neurologic signs such as seizures and muscle twitching. Because the signs are caused by a rickettsial organism, treatment is with a tetracycline-type of drug. Left untreated, 90% of dogs will die. Praziquantel is usually given to eliminate the fluke in order to prevent contamination of other waterways.

Answer 180

Answer: **It causes decreased colonic pH, preventing ammonia absorption.** Explanation The correct answer is that it decreases colonic pH preventing absorption of ammonia. Lactulose is an easily fermented carbohydrate that is metabolized to an acid in the gut. This lowers colonic pH, which keeps ammonia in its ionized form, NH4+, rather than as NH3. The ionized form is not absorbed and is excreted. Lactulose also acts through a number of other mechanisms. It is a cathartic and causes decreased intestinal transit time, leading to decreased absorption of ammonia. It also prevents ammonia formation through a process known as catabolite repression. Finally, it is a carbohydrate source which can be used by colonic flora as an alternative to protein, preventing ammonia formation.

Answer 181

Answer: **Submucosa** Explanation The correct answer is the submucosa. At one time, it was thought that the mucosa was the holding layer, but it has now been shown that it is the submucosa. The submucosa is essentially the holding layer for all hollow viscera.

Answer 182

Answer: **Preputialis muscle** Explanation The correct answer is preputialis muscle. This muscle is usually cut when making a midline incision in male dogs and should be incorporated into the closure to avoid penile deviation.

Answer 183

Answer: **There is a hypoechoic pancreas with hyperechoic surounding mesentery** Explanation The correct answer is there is a hypochoic pancreas with hyperechoic surrounding mesentery. Sometimes, the pancreas will also be enlarged and may appear mottled. The pancreas appears hypochoic due to edema, and the mesentery appears hyperechoic due to focal peritonitis.

Answer 184

Answer: **Roundworm** Explanation The correct answer is roundworm. The roundworm, Toxocara canis, is the most common cause of visceral larval migrans in humans. Transmission is usually fecal-oral. Puppies may acquire the disease transplacentally. ***PowerPage: Selected Parasites of Small Animal Species: Nematodes

Answer 185

Answer: **Active abdominal contactions indicates voming** Explanation The correct answer is active abdominal contractions indicates vomiting. Regurgitation is a passive event that does not have abdominal contractions. pH can be variable with either regurgitation or vomiting, depending on the food eaten and whether the vomiting is gastric or duodenal in origin. Salivation is a sign of nausea that generally indicates vomiting rather than regurgitation. Regurgitation can occur hours after a meal, especially in cases of megaesophagus, where the food sits in the esophagus until the animal positions itself in such a way that the expulsion of food occurs.

Answer 186

Answer: **The dog should be treated for fleas and tapeworms** Explanation The correct answer is the dog should be treated for fleas and tapeworms. Fleas are a required intermediate host of Dipylidium caninum. Dogs become infected by swallowing fleas that carry the tapeworm eggs. Finding proglottids of this tapeworm in the feces or perianally indicates the presence of fleas on the dog.

Answer 187

Answer: **PT (prothrombin time), PTT (activated partial thromboplastin time), FDP (fibrin degradation product)** Explanation Diseases that cause severe inflammation can induce disseminated intravascular coagulation (DIC) complex. The severe inflammation from pancreatitis can cause massive endothelial injury, resulting in vasculitis. This starts the coagulation cascade, which can be so severe that it uses up all the clotting factors; the patient then becomes susceptible to bleeding disorders. DIC can be difficult to diagnose especially in the early stages of the disease, when the clinician would most like to discover it. Patients with clinical signs and the 3 of the following 4 laboratory findings have DIC (increased PT, increased PTT, increased FDP and decreased PLT)

Answer 188

Answer: **TLI (trypsin-like immunoreactivity)** Explanation The correct answer is TLI. This is a sensitive test for pancreatic exocrine function. PLI is a test used more for diagnosing pancreatitis. Vitamin B12/folate levels would be a useful test to do in cases of EPI because of possible malabsorption of folate or concurrent bacterial overgrowth in the small intestine affecting these factors, but it is not a very sensitive test for diagnosing EPI. Fecal examination is also an unreliable way to try to diagnose pancreatic disease but may be useful for ruling out other causes of diarrhea. ***PowerPage: Pancreatitis and Exocrine Pancreatic Insufficiency

Answer 189

Answer: **Urine protein: creatinine ratio** Explanation Patients with protein-losing nephropathy should be monitored closely for increasing levels of proteinuria using the urine protein:creatinine ratio. This test is superior to the simple dipstick protein level, as it is not affected by urine-specific gravity. Checking blood albumin levels and monitoring for signs of azotemia are also useful for these patients. You would consider a urine culture and sensitivity to rule out an underlying urinary tract infection or an abdominal ultrasound to search for abnormalities of the kidneys and bladder. The BUN:creatinine ratio gives limited information regarding whether azotemia is renal or pre-renal in origin but would not help you monitor increases in protein levels in the urine. Blood pressure is always a good value to keep track of in a patient with renal disease, but again, it would not help to determine changes in protein.

Answer 190

Answer: **End expiratory thorax** Explanation The correct answer is end expiratory thorax. An end inspiratory view should be part of any normal thoracic radiograph series. An end-expiratory view is needed to document tracheal collapse in order to demonstrate intrathoracic tracheal narrowing because intrathoracic pressure is highest at end expiration which may worsen intrathoracic airway collapse. Standing lateral views are sometimes used to look for pleural effusion or pneumothorax. Oblique thorax projections are not used ***PowerPage: Collapsing Trachea

Answer 191

Answer: **LOW FIO2** Explanation The correct answer is low FIO2. If you note a low FIO2, the animal will not be obtaining enough oxygen and will ultimately become hypoxemic. Hypoventilation (not hyperventilation) will lead to a lack of oxygen. Manual ventilation (or mechanical ventilation) would not cause hypoxemia, it would help to lower the CO2 when a patient is hypoventilating.

Answer 192

Answer: **Histopathology** Explanation The correct answer is histopathology. Diagnosis of nasal aspergillosis is based on demonstrating the organism in diseased tissue. A CT is great for looking at turbinate destruction but can look very similar if there is a nasal tumor. Cytology usually does not reveal fungal hyphae. Fungal culture is very unreliable; about one third of dogs with nasal tumors may have growth on fungal culture. Serology is also riddled with false negatives and positives. Histopathology usually reveals pyogranulomatous inflammation and necrosis with numerous fungal hyphae. The yield of biopsies can be greatly improved with assistance from rhinoscopy where white fungal plaques are often visualized. Diagnosis is sometimes made from rhinoscopy alone although this is less definitive than histopathology.

Answer 193

Answer: **Aspiration pneumonia** Explanation Lucy's presentation is typical for a dog with laryngeal paralysis. The arytenoid cartilages fail to abduct during inspiration, resulting in upper airway obstruction. These patients often present with acute clinical signs even though the disease is chronic in nature. Surgical arytenoid lateralization (tie-back) is the treatment of choice but with the chronically opened airway, aspiration pneumonia can be a common side effect. If surgery is not an option, prednisone can be given to help reduce laryngeal inflammation.

Answer 194

Answer: **Doxapram** Explanation Doxapram is a central nervous stimulant that has effects on respiratory centers. It is thought that it may work by stimulating the reflex activation of carotid and aortic chemoreceptors. At one point, it was used in critical care patients during resuscitation efforts; however, this has fallen out of favor since doxapram results in increased work associated with respiration without an increased amount of arterial oxygenation. When performing a laryngeal exam, the goal is to have the patient just deep enough so you can perform a laryngeal exam. Injectable anesthetics such as thiopental or propofol are used. Overzealous administration of these can result in a false diagnosis of laryngeal paralysis and it is therefore recommended to administer Doxapram to help stimulate respiration and definitively confirm your diagnosis. Ketamine is an NMDA antagonist and can result in increased jaw tone as well as overall muscle tone. Although its cardiopulmonary effects are minimal, it does not stimulate respiration. Dopamine is a precursor to norepinephrine and acts on alpha and beta-1 receptors. It is typically used in critical care settings to help increase blood pressure. Diphenhydramine is the antihistamine also known as Benadryl. It competitively inhibits histamine at H1 receptors. Along with its antihistamine properties, it has sedative and anti-tussive effects. Propofol is a rapid acting injectable anesthetic which can result in hypotension, bradycardia, and apnea. ***PowerPage: Laryngeal Paralysis

Answer 195

Answer: **Excision with wide surgical margins** Explanation The correct answer is excision with wide surgical margins. If a primary lung tumor can be excised with wide margins, usually with a lung lobectomy, this is the best chance for a cure. Chemotherapy may be useful in cases where the tumor cannot be excised. Long-term prognosis is still guarded because benign pulmonary neoplasia is uncommon.

Answer 196

Answer: **Actinomyces** Explanation The correct answer is Actinomyces. This is a filamentous, branching, gram positive bacteria that is a normal inhabitant of the mouth and oropharynx. It is commonly associated with grass awn migration. These are usually contaminated in the oropharynx and then migrate through the body from the respiratory or Gl tracts. Many times it takes months to years to make a diagnosis. Nocardia is a ubiquitous soil saprophyte found everywhere and is usually introduced via the respiratory tract.

Answer 197

Answer: **Doxapram** Explanation Doxapram is a central nervous stimulant that has effects on respiratory centers. It is thought that it may work by stimulating the reflex activation of carotid and aortic chemoreceptors. At one point, it was used in critical care patients during resuscitation efforts; however, this has fallen out of favor since doxapram results in increased work associated with respiration without an increased amount of arterial oxygenation. When performing a laryngeal exam, the goal is to have the patient just deep enough so you can perform a laryngeal exam. Injectable anesthetics such as thiopental or propofol are used. Overzealous administration of these can result in a false diagnosis of laryngeal paralysis and it is therefore recommended to administer Doxapram to help stimulate respiration and definitively confirm your diagnosis. Ketamine is an NMDA antagonist and can result in increased jaw tone as well as overall muscle tone. Although its cardiopulmonary effects are minimal, it does not stimulate respiration. Dopamine is a precursor to norepinephrine and acts on alpha and beta-1 receptors. It is typically used in critical care settings to help increase blood pressure. Diphenhydramine is the antihistamine also known as Benadryl. It competitively inhibits histamine at H1 receptors. Along with its antihistamine properties, it has sedative and anti-tussive effects. Propofol is a rapid acting injectable anesthetic which can result in hypotension, bradycardia, and apnea. ***PowerPage: Laryngeal Paralysis

Answer 198

Answer: **Meibomian adenoma** Explanation The correct answer is meibomian adenoma. The description fits the appearance and location of a meibomian gland adenoma. This is the most common ocular tumor of the dog and is usually benign. A chalazion is an obstruction of the meibomian gland and appears as a swelling within the eyelid rather than projecting from it. Entropion is an infolding of the eyelid. Melanoma is a reasonable differential but is less common, especially with the location of this mass at the eyelid margin.

Answer 199

Answer: **Blood urea nitrogen (BUN)** Explanation The correct answer is blood urea nitrogen (BUN). ALT and ALP are liver enzymes and can indicate ongoing damage to the liver or cholestasis but do not tell you anything about liver function. Creatinine is produced by muscle and cleared by the kidney so it tells you nothing about liver function. Urea is produced by the liver and is one measure of liver function; it will be low in cases of liver failure. Other tests of liver function on a routine chemistry panel are cholesterol, glucose, bilirubin, and albumin. Bile acids also test liver function but are not on a routine chemistry panel. It is important to realize that in cases of end-stage liver failure, the liver function parameters will be affected, while frequently, liver enzymes will be normal. ***PowerLecture: Liver Enzymes

Answer 200

Answer: **Physis** Explanation The correct answer is the physis. A type I Salter-Harris fracture is physeal only. Type Il involves the physis and metaphysis, type Ill involves the physis and epiphysis, type IV involves physis, metaphysis, and epiphysis, and type V is a compression injury to the physis.

Answer 201

Answer: **4-Methylpyrazole** Explanation The correct answer is 4-Methylpyrazole (4-MP). It is used to inhibit alcohol dehydrogenase and is considered the preferred treatment for treating ethylene glycol toxicoses in dogs. 4-MP does not cause hyperosmolality, metabolic acidosis, and CNS depression like ethanol treatment can. 4-MP is given to dogs IV over a 36-hour period. The initial dose is 20 mg/kg (slow IV over 15-30 minutes), then 15mg/kg (slow IV) at 12 and 24 hours, and then 5mg/kg is given at 36 hours. 4-MP is not effective in cats. *** PowerPage: Toxins in the Garage (ethylene glycol, household cleaners)

Answer 202

Answer: **Alkalizing diet and allopurinol therapy** Explanation The stones in the image are most consistent with the appearance of urate stones, but even without recognizing their appearance, you should be able to guess that the dog has urate stones based on the Dalmatian breed, as they are highly predisposed to forming urate stones, and the apparent radiolucency of the stones since they were not visible radiographically. Urate stone formation is promoted by acidic urine and diets high in purines which are metabolized to uric acid. Generally a low-purine alkalizing diet is recommended. Allopurinol therapy may also be used to reduce uric acid production but it requires monitoring as it may predispose dogs to different types of stones (Xanthine). Soy is high in purines and is not recommended for dogs prone to forming urate stones. Cuprimine and 2-MPG are treatments used for cystine stones. A low salt diet is sometimes used for dogs with calcium phosphate stones because high sodium intake increases urinary calcium.

Answer 203

Answer: **Topical administration of imidacloprid and permethrin** Based on the signalment, history, and physical findings, you should be most suspicious of flea allergy dermatitis (FAD). FAD can occur in any aged dog but typically dogs over 6 months of age. Unlike canine atopy and food allergies which usually have a gradual onset of pruitic signs, FAD can have a rapid onset, as described in this case. Additionally, the distribution and description of the lesions over the caudal half of the body are classic for canine FAD. The most common sites affected for atopy or food allergy are the face, paws, distal extremities, ears, and ventrum. There are many treatment options for FAD including: - Imidacloprid (Advantage), also available with 44% permethrin as "Advantix". - Fipronil & S-Methoprene (Frontline Plus) - Selamectin (Revolution) - Nitenpyram (Capstar) - Lufenuron (Program), also available with milbemycin as (Sentinel) - Spinosad (Comfortis) - Dinotefuran, Permethin & Pyriproxifen (Vectra 3D) - Afoxolaner (Nexgard) In addition to insecticidal treatments, flea allergy sometimes needs to be treated with anti-pruritic or antibiotic drugs to address secondary infection; however, the question is specifically asking for treatment of the primary underlying etiology, which, in this case, is the presence of fleas. Hyposensitization injections would be the treatment for atopic dermatitis. A dietary change would be appropriate for food allergy. Antibiotics would be appropriate for a primary pyoderma. Cyclosporine is an adjunct therapy used in atopic dogs. ***PowerPage: Flea Allergy Dermatitis

Answer 204

Answer: **The puppy likely has canine scabies, which is zoonotic. Contact with the puppy should be limited and gloves should be worn when handling the dog.** Explanation The correct answer is the puppy likely has canine scabies which is zoonotic. Contact with the puppy should be limited and gloves should be worn when handling the dog. It is not uncommon for skin scrapings of a scabies patient to be negative for the mite. The signalment, lesion distribution, and clinical impression are sufficient for diagnosing a scabies infestation. Scabies infections are not associated with a genetic defect and are usually responsive to treatment with agents like ivermectin, amitraz, milbemycin oxime, or selamectin. Although the mites are fairly host-specific, they are still considered zoonotic and precautions should be taken when handling the animal.

Answer 205

Answer: **Subarachnoid space** Explanation A myelogram is a positive-contrast radiographic study where a contrast agent such as iohexol or iopamidol is injected into the subarachnoid space where CSF accumulates.

Answer 206

Answer: **Most dogs with FCE usually get better on their own with nursing care** Explanation The correct answer is most dogs with FCE usually get better on their own with nursing care. FCE is caused by an embolus of disc material in the spinal vasculature. It is unknown how the disc material gets into the vasculature. The prognosis of dogs with FCE varies. Most dogs get better with supportive and nursing care. The loss of pain perception and lower motor neuron signs are poor prognostic indicators.

Answer 207

Answer: **Most dogs with FCE usually get better on their own with nursing care** Explanation The correct answer is most dogs with FCE usually get better on their own with nursing care. FCE is caused by an embolus of disc material in the spinal vasculature. It is unknown how the disc material gets into the vasculature. The prognosis of dogs with FCE varies. Most dogs get better with supportive and nursing care. The loss of pain perception and lower motor neuron signs are poor prognostic indicators.

Answer 208

Answer: **Right lateral recumbency abdominal radiograph** Explanation A typical GDV occurs with repositioning of the pylorus to the left dorsal abdomen. A right lateral radiographic image is the best position for revealing a gas filled left dorsally-displaced pylorus with a gas-filled ventral fundus separated by a soft tissue band (compartmented stomach). Although the features of a malpositioned stomach may be observed on the other radiographic views, they are often more difficult to interpret than that represented by the right lateral recumbency view. The severe amount of gas within the Gl tract that is associated with GDV would make ultrasound exam interpretation extremely difficult at best. *** Gastric Dilatation Volvulus

Answer 209

Answer: **Right trigeminal neuropathy** Explanation The correct answer is right trigeminal neuropathy. Hopefully, you were able to identify the presence of significant muscle atrophy of the right masseter and temporalis musculature. The nerve innervating these muscles is the trigeminal nerve. Recall that the trigeminal nerve (cranial nerve V) has primarily a sensory function, with the exception of innervating the muscles of mastication. The facial nerve (CN VII) innervates the muscles of facial expression and is the main motor nerve innervating the face but is not responsible for the muscles that are atrophied in this case. Masticatory muscle myositis is an autoimmune condition that chronically leads to atrophy of the same muscle group, but what differentiates this case is that the signs are unilateral. Idiopathic polyradiculoneuritis is the medical term for a condition sometimes referred to as Coonhound paralysis, which is a condition that diffusely affects all motor nerves.

Answer 210

Answer: **Right trigeminal neuropathy** Explanation The correct answer is right trigeminal neuropathy. Hopefully, you were able to identify the presence of significant muscle atrophy of the right masseter and temporalis musculature. The nerve innervating these muscles is the trigeminal nerve. Recall that the trigeminal nerve (cranial nerve V) has primarily a sensory function, with the exception of innervating the muscles of mastication. The facial nerve (CN VII) innervates the muscles of facial expression and is the main motor nerve innervating the face but is not responsible for the muscles that are atrophied in this case. Masticatory muscle myositis is an autoimmune condition that chronically leads to atrophy of the same muscle group, but what differentiates this case is that the signs are unilateral. Idiopathic polyradiculoneuritis is the medical term for a condition sometimes referred to as Coonhound paralysis, which is a condition that diffusely affects all motor nerves.

Answer 211

Answer: **Fluconazole, free T4** Explanation From the options listed, fluconazole is the best treatment plan for this dog's Malassezia dermatitis. Griseofulvin is an antifungal but is expensive and causes myelosuppression and gastrointestinal upset; it is not the first choice for Malassezia dermatitis. Other azoles like itraconazole and ketoconazole are also good choices. Terbinafine is being used more often for Malassezia dermatitis since it has fewer side effects than azoles. Ketoconazole, itraconazole, and fluconazole can be hepatotoxic. Underlying causes of Malassezia dermatitis include allergies, endocrinopathy, immunodeficiency syndromes, and other systemic illnesses. This dog is presenting with classic signs of an endocrinopathy with initially non-pruritic symmetrical alopecia. The clinical signs of lethargy and weight gain along with the blood work results is indicative of hypothyroidism, and your next diagnostic step would be a free T4. Intradermal testing is not recommended at this time, since the dog was initially not itchy and only became pruritic presumably after infection with Malassezia. Doxycycline would not be indicated since it is an antibiotic.

Answer 212

Answer: **Fluconazole, free T4** Explanation From the options listed, fluconazole is the best treatment plan for this dog's Malassezia dermatitis. Griseofulvin is an antifungal but is expensive and causes myelosuppression and gastrointestinal upset; it is not the first choice for Malassezia dermatitis. Other azoles like itraconazole and ketoconazole are also good choices. Terbinafine is being used more often for Malassezia dermatitis since it has fewer side effects than azoles. Ketoconazole, itraconazole, and fluconazole can be hepatotoxic. Underlying causes of Malassezia dermatitis include allergies, endocrinopathy, immunodeficiency syndromes, and other systemic illnesses. This dog is presenting with classic signs of an endocrinopathy with initially non-pruritic symmetrical alopecia. The clinical signs of lethargy and weight gain along with the blood work results is indicative of hypothyroidism, and your next diagnostic step would be a free T4. Intradermal testing is not recommended at this time, since the dog was initially not itchy and only became pruritic presumably after infection with Malassezia. Doxycycline would not be indicated since it is an antibiotic.

Answer 213

Answer: **Siberian Husky** Explanation The correct answer is Siberian Husky. This syndrome has also been seen in Alaskan Malamutes. They develop a crusting skin disease referred to as Zinc Responsive Dermatosis, where there is scaling, crusting, and alopecic dermatitis most frequently around the eyes, ears, prepuce, scrotum and vulva. Absolute dietary deficiency of Zinc is rare. Zinc responsive dermatosis is related to defective intestinal absorption of Zinc. Oral Zinc supplementation can bring rapid resolution in most patients.

Answer 214

Answer: **Indolent corneal ulcer** Explanation The correct answer is indolent corneal ulcer. The 2-week duration and staining pattern are typical of indolent ulcers. Boxers are also frequently affected by this condition. An indolent ulcer occurs due to a defect in the ability of the corneal epithelium to adhere. PowerLecture: Indolent Corneal Ulcers

Answer 215

Answer: **Sebaceous gland tumor** Explanation The correct answer is sebaceous gland tumor. These are actually the most common skin tumor in the dog. This group of tumors includes sebaceous hyperplasia, sebaceous epithelioma, sebaceous adenoma, and sebaceous adenocarcinoma. They are usually found in older dogs and are especially common in Cockers, Beagles, Poodles, and Miniature Schnauzers. They usual look like wart- or cauliflower-like lesions < 1 cm and can occur anywhere but usually are seen on the limbs, trunk, and eyelids.

Answer 216

Answer: **Ixodes pacificus** Explanation The correct answer is Ixodes pacificus. Ticks acquire the infection at any stage and are most likely to get it from the white-footed mouse, Peromyscus leucopus. Dermacentor variabilis and Dermacentor andersoni are known to transmit Rocky Mountain Spotted Fever. Amblyomma americanum may transmit canine granulocytic ehrlichiosis which is caused by E. ewingii and Anaplasma phagocytophila. Rhipicephalus sanguineus is known to transmit Ehrlichia canis.

Answer 217

Answer: **Confine the dog and observe it for 10 days** Explanation The correct answer is confine pet and quarantine for 10 days. With a healthy, vaccinated dog, the 10 day confinement period can be carried out in the owner's home. You would only need to euthanize and test if the dog is an unvaccinated stray. If the dog was not up-to-date on vaccinations, you would either euthanize and test or quarantine for 10 days in an approved facility. The answer choice to vaccinate the dog immediately and quarantine for 45 days would be recommended if the dog were bitten by an animal that was rabid or suspected to be rabid.

Answer 218

Answer: **L-asparaginase - anaphylaxis** Explanation L-asparaginase is a protein enzyme and therefore may elicit an immune response. Anaphylaxis is rare but usually would occur only after a patient had received a prior dose and developed antibodies to it. Vincristine is associated with paralytic ileus. Lomustine is associated with hepatotoxicity. Doxorubicin is associated with cardiotoxicity. Cystitis is associated with cyclophosphamide. Pancreatitis is associated with L-asparaginase or doxorubicin.

Answer 219

Answer: **0.1 mg/kg preservative free morphine given epidurally** Explanation Epidural morphine is an effective analgesic for 12-24 hours, while lidocaine lasts only several hours. Fentanyl is a short acting opioid and would only be effective over 12 hours if given repeatedly or as a constant rate infusion (CRI). The effects of hydromorphone last only 4-6 hours.

Answer 220

Answer: **A thin female dog** Explanation The correct answer is a thin female dog. Urohydropropulsion is the expulsion of cystic calculi after anesthetizing an animal by application of manual pressure to the urinary bladder to expel the stone through the urethra. Urohydropropulsion should not be attempted in male dogs because they have long, narrow urethras compared to females and an os penis which increases the likelihood of the calculi becoming lodged in the urethra. Obesity (and large size in general) makes it more difficult to manipulate the bladder effectively.

Answer 221

Answer: **Catecholamines** Explanation A pheochromocytoma is a tumor of the adrenal medulla. To review, the adrenal gland is composed of the adrenal cortex (outer layer) which is divided into the zona glomerulosa, zona fasciculata, and zona reticularis. The zona glomerulosa is the main site of aldosterone production. The zona fasciculata produces glucocorticoids (mainly cortisol). The zona reticularis is the site of androgen production. The adrenal medulla is the inner part of the adrenal gland and consists of chromaffin cells. These cells are responsible for making catecholamines (epinephrine and norepinephrine). ***PowerLecture: Pheochromocytomas

Answer 222

Answer: **Struvite urolithiasis. Treat with culture-based antibiotics, and either dietary dissolution or surgical removal of stones.** Explanation Large bladder stones in the presence of UTI and alkaline urine are usually struvite, particularly when accompanied by struvite (magnesium ammonium phosphate) crystalluria. In dogs, struvite stones are almost invariably infection-associated. The infecting organisms are usually urease-producers (Staphylococus, Proteus, Klebsiella, some E. coli) which alkalinize the urine and favor struvite formation. The single most important long-term management is prevention of infection. Calcium oxalate stones are usually small (1 cm or less), are often present in the absence of UTI, and cannot be dissolved. Cystine stones occur most often in Newfoundland dogs, dachshunds, and bulldogs. They are radiolucent and occur due to metabolic defects. Urate stones are usually small and many. They are frequently radiolucent and can be related to underlying liver disease.

Answer 223

Answer: **Fluids, low protein diet, and gastric protectants** Explanation The image shows polycystic kidneys. This is an inherited disease that most commonly affects Persian cats. Other breeds such as Himalayans and British shorthairs are occasionally affected as well. The responsible gene is autosomal dominant. The homozygous form is lethal in utero and all affected living cats are heterozygotes. The disease is diagnosed most reliably by ultrasound and treatment is similar to that of other causes of chronic renal disease with fluids, a low protein diet, gastric protectants (such as famotidine), maropitant, and appetite stimulants. Cyclophosphamide, doxorubicin, vincristine, and prednisone are treatments for lymphoma, which can also affect kidneys bilaterally, but generally the lesions would not be cystic in appearance such as those in the picture. Typically, the cysts are diffuse throughout both kidneys so surgical excision is not an option. Antibiotics such as ampicillin and enrofloxacin are not usually necessary unless a concurrent infection is found. Lithotripsy is a form of treatment used to break up urinary calculi which is not commonly employed in animals.

Answer 224

Answer: **Blastomycosis (Blastomyces dermatiditis)** Explanation The correct answer is blastomycosis. These findings are most consistent with blastomycosis. Lymphoma would be a great differential but is less consistent with the nodular lung pattern and suppurative inflammation in the lymph node. Plague is an interesting differential for the lymphadenopathy and cytology findings but is not consistent with the lung pattern or history. This Weimaraner's disease is too severe to be explained by kennel cough alone. While this diagnosis is sometimes made easy by visualization of organisms in aspirates or skin scrapings, it is not always seen as in this case. Remember, Blastomyces is seen as a broad-based budding yeast. The next step to obtain a definitive diagnosis in this patient would be a transtracheal wash or bronchoalveolar lavage.

Answer 225

Answer: **20 cmH2O** Explanation Pressures above 20cm H20 may result in barotrauma. In an otherwise healthy patient it is not recommended to exceed this pressure. In patients with chronic atelectasis, anesthetists will be much more apprehensive about over ventilating or ventilating the lungs too quickly, as acute expansion can trigger re-expansion pulmonary edema, which may then lead to acute respiratory distress syndrome and death.

Answer 226

Answer: **Removing a fragment from the medial aspect of the ulna** Explanation Elbow dysplasia is a global term for several congenital conditions which can occur. These include an ununited anconeal process, osteochondrosis of the humeral condyle, elbow incongruency, and a fragmented medial coronoid process. The fragmented medial coronoid process tends to be the most commonly encountered condition. Left untreated, the abnormal region may not only be fragmented and painful, but can also result in eventual cartilage eburnation of the apposing humeral condyle. The coronoid process is located on the ulna. In elbow dysplasia, osteochondrosis dissecans is always associated with the medial humeral condyle. Osteochondrosis dissecans does not occur at the level of the medial coronoid process of the ulna. One theory of why dogs develop a fragmented medial coronoid process is that excessive stress along the medial aspect of the limb results in overloading of the medial coronoid process, which leads to its eventual fragmentation.

Answer 227

Answer: **Epiphysis and physis** Explanation The correct answer is the epiphysis and physis. A type I Salter-Harris fracture is physeal only. Type Il involves the physis and metaphysis, type Ill involves the physis and epiphysis, type IV involves physis, metaphysis, and epiphysis, and type V is a compression injury to the physis.