Dogs Flashcards
A 6-year old male neutered terrier mix weighing 10kg presents to you after having ingested 3 pieces of sugar-free gum containing xylitol. What bloodwork abnormality are you expecting to find?
Hypernatremia
Hyperglycemia
Hypoglycemia
Hypocalcemia
Hyponatremia
Answer: Hypoglycrmia
Explanation
Xylitol is a sugar alcohol present in sugar-free gum that, when ingested, causes a rapid release of insulin in dogs.
After ingestion, clinically significant hypoglycemia can develop within 30 minutes and can last for more than 12 hours. Acute hepatic necrosis and failure after higher doses of xylitol ingestion can occur as well.
A 6-year old female spayed English Pointer presents for lethargy and weight gain. The owner notes that the dog is eating and drinking a normal amount, but the dog is still gaining weight. A physical exam reveals weak pelvic limbs, facial nerve paralysis, a symmetrically patchy haircoat, and seborrhea. Lab work reveals a normocytic, normochromic anemia with a PCV of 29% (35-57%), lipemic serum, and cholesterol of 1090 mg/dl (135-278 mg/dl). What is the most likely diagnosis?
Hypothyroidism
Hyperthyroidism
Pituitary dependent hyperadrenocorticism
Adrenal dependent hyperadrenocorticism
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.
A 1-year old German Shepherd Dog presents for its first physical exam. Cardiac auscultation reveals a continuous murmur. Thoracic radiographs and echocardiography lead you to the diagnosis of a very large, cylinder-shaped patent ductus arteriosus with left-to-right shunting of blood. Which of the following statements is most true?
Furosemide and enalapril are the most appropriate forms of treatment for a cylinder-shaped PDA
Coil embolization is the most appropriate form of treatment for a cylinder-shaped PDA
Surgical ligation is the most appropriate form
of treatment for a cylinder-shaped PDA
Placement of constrictor ring is the most appropriate form of treatment for a cylinder-shaped PDA
Answer: Surgical ligation is the most appropriate form
of treatment for a cylinder-shaped PDA
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.
A 12 year old female spayed Spaniel mix presents for progressive lethargy over the last week. This morning, the owner noticed the dog was having a hard time breathing and had pale gums. A blood smear from the dog is shown below.
The larger arrow is pointing to which type of cell?
Nucleated red blood cell
Monocyte
Lymphocyte
Myelocyte
Answer: Nucleated red blood cell
The larger arrow is pointing to a nucleated red blood. These are immature erythrocytes that have been released early from the bone marrow in response to the dog’s anemia and increased need for oxygen carrying capacity.
These cells are typically larger than a mature erythrocyte, have a very dark purple nucleus, and have basophilic cytoplasm. There are 3 nucleated red blood cells in this picture.
Monocytes are essentially macrophages found in the blood whose function is phagocytosis. They have a blue-gray cytoplasm and a lobulated or bean shaped nucleus.
Lymphocytes are typically about the size of a red blood cell and are mostly made up of a nucleus with just a slender rim of cytoplasm. They are involved with antibody production as well as cell mediated immunity.
Myelocytes are immature granulocytes that should normally only be found in the bone marrow.
A 12-year-old male intact English bulldog presents to your hospital for a drop of blood noted coming from the penis. The dog has no other prior medical history. On examination, both testicles are descended and palpate normal in size. A rectal exam reveals a large, but symmetrical prostate gland. You extrude the penis and note what is illustrated in the image below. What is your recommendation to the owner?
There is an abscess of the penile tip, likely of bacterial origin. We should begin antibiotic therapy once we obtain a culture.
This is a urethral prolapse and can be repaired by performing a urethropexy.
There is a mass at the tip of the penis, which will likely respond to radiation therapy.
There is a mass at the tip of the penis suspicious for a mast cell tumor. You should amputate the tip and submit it for histopathology.
Answer: This is a urethral prolapse and can be repaired by performing a urethropexy.
The image is classic for a urethral prolapse. This condition is almost exclusive to young English bulldogs. It is interesting that this patient was incidentally 12 years of age. The cause of urethral prolapse is not always determined but may be secondary to excessive masturbation, sexual excitement, or an infection. Treatment involves either urethropexy to replace the prolapse or amputation of the tip. The patient should be examined closely to ensure there is no evidence of concurrent neoplasia or infection.
Lucy is an 11 year-old female spayed Labrador retriever presenting in acute respiratory distress after playing fetch on a hot summer day. On initial exam, Lucy is panting heavily and a loud stridor is audible. Upon further history-taking the owners tell you that Lucy’s bark has changed over the past couple of months. What is the most common complication/side effect of the recommended treatment for Lucy’s condition?
Drooling
Megaesophagus
Aspiration pneumonia
Tracheal collapse
Kidney disease
Answer: Aspiration Neumonia.
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.
A 2-year-old neutered male greyhound presents for crusting along his ear pinnae and elbows. The owner also explains that the dog is intensely pruritic. The dog mainly lives indoors but is also let outside into the backyard. The owner lives on a large rural property that is heavily wooded. You perform cytology, which returns negative for bacteria and yeast. You are highly suspicious of Sarcoptes. Which of the following would be most useful to help in your diagnosis of Sarcoptic mange?
Superficial skin scrape, histopathology, trichogram
Deep skin scrape, pinnal-pedal reflex, clinical signs
Histopathology, deep skin scrape, trichogram
Pinnal-pedal reflex, clinical signs, superficial skin scrape
Clinical signs, superficial skin scrape, trichogram
Answer: Pinnal-pedal reflex, clinical signs, superficial skin scrape
A superficial skin scrape is most useful. A deep skin scrape is used for Demodex mites, which reside in the hair follicles. Superficial skin scraping is indicated for Sarcoptic mange, since this mite lives in the stratum corneum.
Pinnal-pedal reflex can be positive in 70% of Sarcoptic mange infestation but can also be positive in any dog with pruritus. Clinical signs are helpful because Sarcoptes typically infects the non-haired portions of the skin such as the ear pinnae, elbows, hocks, and ventral abdomen. If the mite is not found on skin scraping and you have clinical signs indicative of Sarcoptes then a therapeutic trial is warranted. Keep in mind that in most cases you will not be able to find the mite.
A trichogram would not be indicated. This method can be used to diagnose dermatophytosis and sometimes Demodex. Histopathology will reveal a perivascular dermatitis that is non-specific. Rarely are the mites found on histopathology.
A 10 year old female spayed Schipperke dog presents to your emergency clinic for profuse vomiting for several days and weakness. You perform initial bloodwork and find that her blood pH is 7.6 (7.35-7.45) and her potassium is 1.8 mmol/L (3.4-4.9 mmol/L). She weighs 12 kg. You immediately start her on intravenous fluids supplemented with potassium. What is the maximum rate of intravenous potassium that would be considered safe to administer to this dog?
6 mEq/hr
12 mEq/hr
24 mEq/hr
18 mEq/hr
3 mEq/hr
Answer: 6mEq/hr
Explanation
The maximum safe rate of potassium infusion is 0.5 mEq/kg/hr. As this dog weighs 12 kg, the maximum is 6 mEq/hr. This is one of those rates that you need to know. Administering potassium more rapidly than this can result in fatal arrhythmias.
The best diagnostic test to differentiate pituitary dependent hyperadrenocorticism from adrenal dependent hyperadrenocorticism in dogs is which of the following?
Urine cortisol: creatinine ratio
Serum cortisol
Low-dose dexamethasone suppression test
High-dose dexamethasone suppression test
Answer: High-dose dexamethasone suppression test
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.
Which is a cause of primary bacterial pneumonia in dogs?
Bacillus spp.
Bordetella bronchisepica
Pasteurella multocida
Pseudomonas spp.
Answer: Bordetella bronchiseptica.
Explanation
Although not common, Bordetella infections can develop into a primary pneumonia, particularly if the dog has a weakened immune system. The other choices require an underlying problem such as aspiration, foreign body, viral infection, neoplasia, etc. to be present in order to create an infection.
Secondary bacterial infections can be extremely severe and need to be diagnosed and treated appropriately and aggressively.
Which of the following is the most likely side effect of KBr therapy in epileptic dogs?
Sedation
Pancreatitis
Vomiting
Polyuria and polydipsia
Answer: Sedation.
Explanation
The correct answer is sedation. Possible side effects of KBr therapy include polyphagia, polyuria and polydipsia, ataxia, skin reactions, pancreatitis, and vomiting. However, sedation is more likely to occur than these.
A 7 year old Poodle presents for a left sided head tilt, a ventral strabismus on the left, and right horizontal nystagmus. The dog is obtunded, has conscious proprioception deficits in both right limbs, and a right sided facial paralysis. Where is the lesion?
Peripheral nerve on the right
Central nervous system on the right
Central nervous system on the left
Peripheral nerve on the left
Answer: Central nervous system on the right
Explanation
The correct answer is central nervous system on the right. This dog has paradoxical vestibular disease. This disease is usually caused by a destructive lesion in the CNS in which there is loss of inhibition of the vestibular output on the side of the lesion. There is therefore a relative increase in vestibular output on the side of the lesion, causing vestibular signs on the side opposite the lesion (yes, this can be confusing). In this case, the right sided lesion has vestibular signs that would normally localize the lesion to the left side. When the lesion causes vestibular signs and proprioceptive deficits, the lesion is ipsilateral to the side with the proprioceptive deficits.
A 9-year old female spayed German Shepherd presented for extreme lethargy. Physical examination and diagnostics were consistent with a hemoabdomen.
The patient was taken to surgery and a splenic mass was found (see image). The remainder of your abdominal exploration was unremarkable. What is the most common malignant tumor of the spleen in the dog?
Transitional cell carcinoma
Hemangiosarcoma
Lymphoma
Mast cell tumor
Answer: Hemangiosarcoma
The correct answer is hemangiosarcoma. This tumor accounts for approximately 2/3 of malignant splenic masses and will have metastasized in >90% of cases by the time they are diagnosed. Chemotherapy would be recommended for adjunct therapy after surgical removal of the spleen. Lymphoma is not as commonly found in the spleen in dogs, and you would have expected enlarged lymph nodes to be mentioned in the question. Mast cell tumors occur with some frequency in the spleen of cats but not so often in dogs. Transitional cell carcinomas are typically found in the urinary bladder, since that is where transitional cells are located.
A 3-year old Husky bitch comes to your clinic. The owner tells you that the bitch is in heat and has been receptive to males. Which of the following would you expect to see on vaginal cytology?
B
D
C
A
Answer: C
Dogs in estrus should have cellular vaginal cytology consisting predominantly (>90%) of cornified epithelial cells. This corresponds to image
C.
Image A is from a dog in anestrus, note that it is less cellular. Image B is from a dog in early diestrus.
Image D is from a dog in diestrus.
On routine physical exam, you find Dipylidium caninum segments on the perianal region of a dog. Which of the following assumptions can be made?
The dog was infected in utero by transplacental transmission
The dog acquired the infection by coprophagia
The dog acquired the infection by eating uncooked beef
The dog should be treated for fleas and
tapeworms
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.
Which of the following is an appropriate objective in the repair of an articular fracture in a dog?
6-8 weeks of strict post-operative rest
Early return to function
Avoid rigid fixation of the fracture
50% or greater alignment
Answer: Early return to function.
Explanation
The correct answer is early return to function. With articular fractures, the 3 major goals of the clinician are:
Rigid fixation of the fracture fragments; neglecting to do this will result in loose fracture fragments within the joints that will promote osteoarthritis.
Anatomic realignment (50% or even 75% is not adequate with articular fractures, in contrast to long bone fractures)
Early return to function. With long bone fractures, extended rest is recommended to promote stability and healing of the bone. The opposite is true in articular fractures where prolonged rest after repair will promote fibrosis, causing decreased range of motion in the joint.
Which digit has been partially amputated in the picture below? (hint: this is the right forelimb of a dog)
5th digit
3rd digit
4th digit
1st digit
2nd digit
Answer: 3rd digit
Explanation
The correct answer is 3rd digit. Remember that a dog’s digits are numbered from 1 to 5, starting medially with the small 1st metacarpal that is associated with the dewclaw (essentially like the thumb on a primate). This digit is not well visible in the photograph, but you should still be able to see that it is the third digit that has had the ungual crest and process amputated.
You are treating an 8-year old mix breed terrier for ventricular tachycardia post splenectomy. You determine that you’ve given too much lidocaine to the patient. What clinical signs or laboratory findings are you most likely to see initially?
Muscle tremors and seizures
Bradycardia and hypotension
Increased respiratory rate and difficulty breathing
Methemoglobinemia
Diarrhea
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.
You are treating an 8-year old mix breed terrier for ventricular tachycardia post splenectomy. You determine that you’ve given too much lidocaine to the patient. What clinical signs or laboratory findings are you most likely to see initially?
Muscle tremors and seizures
Bradycardia and hypotension
Increased respiratory rate and difficulty breathing
Methemoglobinemia
Diarrhea
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.
A recently adopted 5-month-old female spayed mixed breed dog presents for vaccines, and you auscult a V/VI murmur at the left heart base. It is a very loud continuous murmur, which sounds like a washing machine. The owner reports normal activity, energy, and appetite. Her gums are pink with good refill. She has strong synchronous pulses. Based on your assessment, you most suspect which of the following?
Patent ductus arteriosus
Heartworm infection
Physiologic murmur
Atrial septal defect
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.
All of the following drugs are appropriate in the management of tachycardia associated with this arrhythmia in small animal patients except:
Isoproterenol
Atenolol
Digoxin
Procainamide
Diltiazem
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.
A 10-year old male castrated Collie presents for what the owner calls heart failure. Which of the following is not a typical sign of right heart failure?
Exercise intolerance
Muscle wasting
Hepatomegaly
Tachypnea
Cough
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.
Which of the following is a non-adrenergic vasoconstrictor that can be used in dogs?
Dobutamine
Isoproterenol
Vasopressin
Epinephrine
Phenylephrine
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.
Dilated cardiomyopathy is a common disease seen in dogs. Which one of the following medications is indicated for the treatment of DCM?
Atropine
Prednisone
Enalapril
Adriamycin
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.
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: 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.
Which of the following is the treatment of choice for pulmonic stenosis in the dog?
Valvulotomy by catheterization device
Balloon valvuloplasty
Surgical valvulotomy
Patch grafting of the outflow tract
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.
A 4-year old male Australian Shepherd is presented to your clinic for treatment of heartworm disease. Which of the following statements about heartworm disease is true?
strict activity restriction of the dog is very important once medical treatment is initiated
Doxycycline can be used to treat heartworms
Ivermectin is the treatment of choice for adult worms
The owners should be informed that dogs often can develop right heart failure post treatment even if the dog was clinically normal pre treatment
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.
Which of the following is a non-adrenergic vasoconstrictor that can be used in dogs?
Epinephrine
Phenylephrine
Vasopressin
Dobutamine
Isoproterenol
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.
Which of the following is the most common treatment for aortic stenosis in a dog?
Surgical repair
Medical management with beta blockers
Medical management with furosemide
Balloon dilation of the stenotic region by catheterization
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.
A 1.5-year old male castrated Boxer presents for exercise intolerance and syncopal episodes. Cardiac auscultation reveals a grade 4/6 left systolic murmur heard best at the base of the heart. Thoracic radiographs show a mildly enlarged left ventricle and left atrium, and segmental enlargement of the ascending aorta. What test will best help you to confirm your tentative diagnosis?
Heartworm antigen test
CT scan
24 hour Holter ECG monitor
Coombs test
Echocardiogram
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.
A 2 year old male castrated Boxer presents for exercise intolerance and syncopal episodes. Cardiac auscultation reveals a 4/6 left systolic murmur heard best at the base of the heart. Thoracic radiographs show a mildly enlarged left ventricle and left atrium, and segmental enlargement of the ascending aorta. What is the most likely diagnosis?
Pulmonic stenosis
Aortic stenosis
Myxomatous degeneration of the mitral valve
Boxer cardiomyopathy
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.
A 9 month old shepherd cross presents for lethargy and exercise intolerance. Your physical exam reveals dark red mucous membranes and a heart murmur. A CBC reveals a hematocrit of 70% (35-57%). Which of the following could NOT explain the given findings?
Atrial septal defect with tricuspid stenosis
PDA with pulmonary hypertension
Atrial septal defect with systemic hypertension
Tetralogy of Fallot
Answer: Atrial septal defect with tricuspid stenosis
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.
A 1-year old German Shepherd Dog presents for its first physical exam. Cardiac auscultation reveals a continuous murmur. Thoracic radiographs and echocardiography lead you to the diagnosis of a very large, cylinder-shaped patent ductus arteriosus with left-to-right shunting of blood. Which of the following statements is most true?
Placement of constrictor ring is the most appropriate form of treatment for a cylinder-shaped PDA
Coil embolization is the most appropriate form of treatment for a cylinder-shaped PDA
Furosemide and enalapril are the most appropriate forms of treatment for a cylinder-shaped PDA
Surgical ligation is the most appropriate form of treatment for a cylinder-shaped PDA
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.
Which of the following drugs and treatment intervals are appropriate for preventing heartworm disease in dogs?
Milbemycin twice daily
Ivermectin once a month
Milbemycin oxime once daily
Ivermectin once daily
Diethylcarbamazine once monthly
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.
Which of the following has the least effect on heart rate?
Morphine
Ketamine
Propofol
Thiopental
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.
Which of the following is true about diltiazem?
Diltiazem slows the heart by antagonizing beta adrenergic receptors.
Diltiazem speeds up the heart because it is a beta adrenergic agonist.
Diltiazem slows the heart by inhibiting the influx of calcium into the myocardial cells.
Diltiazem speeds up the heart rate by increasing the influx of calcium into the myocardial cells.
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.
A 2-year old male castrated Beagle presents for vomiting and diarrhea. The blood smear for a CBC shows microfilariae in the peripheral blood. Which of the following parasites must be ruled out?
Acanthocheilonema reconditum
Filaroides osleri
Strongyloides stercoralis
Uncinaria stenocephala
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.
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.
Which of the following statements is true about central venous pressure?
It is a direct measure of preload
It is an estimation of afterload
it is a direct measure of blood pressure in the cranial vena cava
The measurement is independent of cardiac output
The measurement is independent of venous vessel tone
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.
Which abnormal heart sound are you least likely to be able to auscult in a dog?
Atrial fibrillation
Gallop rhythm
First degree AV block
Sinus arrhythmia
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.
You diagnose a dog with a larger left to right ventricular septal defect with advanced sequelae to the abnormality. Which of the following is the most likely radiographic appearance of this dog’s thorax?
Right ventricular and left atrial enlargement with pulmonary vasculature hypoperfusion
Left atrial and left ventricular enlargement with pulmonary hyperperfusion
Right ventricular enlargement with pulmonary hyperperfusion and a normal left heart
Enlargement of all 4 heart chambers and hyperperfusion of the pulmonary vasculature
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.
A 15-year old male castrated terrier mix presents for cough and rapid, shallow breathing. You auscult a grade IV/VI left apical holosystolic murmur and crackles throughout both lung fields. An echocardiogram is performed, shown here. What findings are shown on this echocardiogram?
Tricuspid valve endocarditis
Mitral valve prolapse
Pulmonic stenosis
Left ventricular concentric hypertrophy
Right ventricular concentric hypertrophy
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.
Mitral regurgitation in dogs eventually results in which of the following?
Eccentric hypertrophy of the left atrium and concentric hypertrophy of the left ventricle
Eccentric hypertrophy of the left atrium and left ventricle
Concentric hypertrophy of the left atrium and eccentric hypertrophy of the left ventricle
Concentric hypertrophy of the left atrium and left ventricle
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.
Which of the following findings is consistent with Tetralogy of Fallot in a dog?
Left ventricular hypertrophy
Aortic stenosis
Polycythemia
Severe generalized cardiomegaly on thoracic radiography
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.
Dopamine is often used for which of the following reasons?
To increase contractility of the heart
To increase heart rate
To increase arterial blood pressure
To decrease blood pressure
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.
A 1-year old German Shepherd Dog presents for its first physical exam. Cardiac auscultation reveals a continuous murmur. Thoracic radiographs and echocardiography lead you to the diagnosis of a very large, cylinder-shaped patent ductus arteriosus with left-to-right shunting of blood. Which of the following statements is most true?
Furosemide and enalapril are the most appropriate forms of treatment for a cylinder-shaped PDA
Coil embolization is the most appropriate form of treatment for a cylinder-shaped PDA
Surgical ligation is the most appropriate form of treatment for a cylinder-shaped PDA
Placement of constrictor ring is the most appropriate form of treatment for a cylinder-shaped PDA
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.
Using phenothiazines in dogs causes which of the following effects?
Increase in hematocrit
Increases in myocardial sensitivity to catecholamine induced arrhythmias in the heart
Hypotension
Analgesia
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.
A 7 year-old male neutered Doberman has recently been diagnosed with dilated cardiomyopathy. On your physical exam, you auscult a “tennis shoes in a dryer” sound. What heart rhythm are you describing?
Bradycardia
Tachycardia
Atrial fibrillation
Respiratory sinus arrhythmia
Atrioventricular block
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.
A 11-year old male castrated Golden Retriever presents for collapse with muffled heart sounds on examination. You ultrasound the heart and obtain the following image; the right atrium (RA) and right ventricle (RV) are labeled. A large mass is seen in the right atrioventricular groove with pericardial effusion. What is the likely diagnosis?
Hemangiosarcoma
Lymphoma
Chemodectoma
Idiopathic pericardial hemorrhage
Pulmonary adenocarcinoma
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.
Which of the following is used as a medical management option in congestive heart failure in a dog?
Lidocaine
Mirtazapine
Increased sodium intake
Furosemide
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.
A 5-year old Pug in an animal shelter dies after experiencing cough, exercise intolerance, and dyspnea as well as ascites and hepatomegaly secondary to congestive heart failure. You perform a necropsy and find the parasite shown in the image below residing primarily in the pulmonary artery. How is this parasite transmitted?
Mosquito
Aerosol
Tick
Fecal-oral
Flea
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.
This ECG recording (bottom recording) is from a 10-year old miniature poodle with a history of heart disease that is untreated. She presented for a 3-day history of diarrhea and decreased appetite. On physical examination you auscult a grade Ill/VI heart murmur and clear lung sounds. There are no obvious pulse deficits palpated. What is the appropriate treatment for this arrhythmia?
Give the patient a bolus of lidocaine and begin continuous infusion for twelve hours and then try to wean off the lidocaine
Begin the patient on oral mexiletine and recheck an ECG strip in 5 days
No anti-arrhythmic therapy is necessary at this time
Give the patient an intravenous injection of furosemide and begin oral administration of furosemide
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.
A 6-year old female spayed Beagle presents for lethargy. On exam you detect a heart rate of 25 beats per minute and record an ECG, which is shown here. What is the treatment of choice?
Pacemaker implantation
Atropine administered intramuscularly
Doxycycline
Furosemide
Sotalol
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.
A 12-year old female Dalmatian has a Holter monitor placed for an arrhythmia heard on exam. The following trace is from that monitor; similar abnormalities were seen frequently throughout the 24hrs. What is your treatment recommendation for this arrhythmia?
Mexiletine
Diltiazem and furosemide
Amlodipine
Pimobendan
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.
A 7-year old male castrated Doberman Pinscher presents for lethargy and anorexia. Your physical exam reveals a 3/6 left systolic heart murmur and a rectal temperature of 103.5F (39.7 C). One of your differential diagnoses for this dog is infective endocarditis. Which area of the heart is most commonly affected in a dog with infective endocarditis?
Mitral and aortic valves
Pulmonic and aortic valves
Mitral and tricuspid valves
Ventricular endocardium
Tricuspid and pulmonic valves
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.
A 9 year old female spayed Greyhound presents to you for evaluation of a cough of 2 weeks duration and respiratory difficulty. The owner reports that the dog collapsed while chasing her ball yesterday. On your exam, heart sounds are quiet and the dog’s mucous membranes appear pale. You elect to take thoracic radiographs which are shown below. What is an appropriate treatment?
Atenolol
Measure taurine levels
Heartworm test
Pericardiocentesis
Furosemide
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.
An 11-year old female spayed Shih Tzu presents for her annual physical exam. She appears to be doing fine at home. Cardiac auscultation reveals a 2/6 left systolic heart murmur over the apex of the heart. Color Doppler echocardiography reveals a small regurgitant jet across the mitral valve. What is the most likely cause for the mitral regurgitation in this dog?
Congenital mitral dysplasia
Bacterial endocarditis
Myxomatous mitral valve degeneration
Systolic anterior motion
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.
A 5-month-old intact female mixed breed presents to your hospital for the progressive lesions seen on the image provided. The owner described the lesions as initially being papules and vesicles that eventually ruptured. Recently, the owner has also noticed that the muscles of the face appear to be atrophied. Muscle and skin biopsies were performed which came back supportive of a diagnosis of dermatomyositis. You start the patient on an immunosuppressive dose of steroids. Which other medication would be useful for the treatment of this condition?
Meloxicam
Zinc
Hycodan
Pentoxifylline
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.
A 1-year old female spayed Doberman Pinscher has presented after being hit by a car. Initial chest radiographs show mild contusions, and the patient appears to be otherwise stable. A right mid-shaft long oblique femoral fracture has been identified. Routine pre-operative blood work is unremarkable. A buccal mucosal bleeding test (BMBT) is elevated at 6 minutes. What will you administer prior to surgery?
1,25 dihydrocholecalciferol
Whole blood transfusion
Desmopressin acetate
Vitamin K
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.
The mean circulating life span of a neutrophil in the dog is approximately________
48 hours
120 minutes
5-9 hours
5-9 days
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.
A 7 year old female spayed Brittany Spaniel presents to your emergency clinic for a several day history of progressive weakness and lethargy. Although she was a hunting dog when she was younger, she has no recent history of travel or tick exposure. On exam, she has a temperature of 104.7F (40.4 C), heart rate of 128 beats per minute, and a respiratory rate of 42 breaths per minute. Her mucous membranes are pale pink with a capillary refill time of 1.5 seconds. Your laboratory is closed, so you perform a blood smear and see the following. Based on the most likely diagnosis for these findings, and assuming you have access to all of these treatment options, which of the following treatments is most appropriate?
Erythropoietin injections and iron supplementation
Platelet-rich-plasma transfusion and anti-inflammatory doses of corticosteroids
Packed red blood cell transfusion, immunosuppressive doses of corticosteroids
Plasma transfusion, vitamin K supplementation
Fresh whole blood transfusion, Ampicillin
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.
A 7-year old female Lhasa Apso presents to you for lethargy and inappetence. On your exam, you detect mandibular lymphadenopathy and perform a fine needle aspirate. You see the aspirate depicted here. Which of these treatments would be given to this patient as part of a first line therapy?
Doxycycline
Milbemycin
Itraconazole
Prednisone
Carboplatin
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.
A 1-year-old male castrated Basset Hound presents for epistaxis from both nostrils, a small amount from blood from the right and a larger amount from the left. There is no history of trauma but he does go for frequent walks, and as a typical Basset, usually has his nose to the ground. His heart and lungs sound normal. You note a few ecchymotic hemorrhages on the thin skin under his abdominal region. You discuss the various causes of this issue with the owner and perform some labwork, including a coagulation panel, and the important values to note are as follows:
PCV 34%
Reticulocytes 110K
Platelets 180K/uL (143-448 K/uL)
Prothrombin Time (PT) 6.95 (6.3-13.3 seconds)
Partial Thromboplastin Time (PTT) 10.95 (10.6-16.8 seconds)
Based on this information, what is your top differential?
Immune-mediated thrombocytopenia
Rodenticide toxicity
Nasal foreign body
Canine thrombopathia
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.
Zinc toxicity from ingestion of pennies minted after 1983 can cause which of the following?
Muscle spasms
Coagulopathy
Hemolysis
Correct Answer
Thrombocytopenia
Answer: Hemolysis
Explanation
The correct answer is hemolysis. Zinc causes a Heinz body anemia and hemolysis.
Immune-mediated hemolytic anemia is classically associated with which type of hypersensitivity reaction?
Type IV
Type Il
Type I
Туре II!
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.
A 7-year old male neutered Golden Retriever presents for lethargy and pale mucous membranes. A purple top (EDTA) tube of blood is drawn. A blood smear is made and examined. There is a moderate regenerative anemia with an increase in spherocytes. Mild agglutination is suspected. Spherocytes are consistent with which disease condition?
Iron deficiency
Grape and raisin toxicity
Cobalamin and folate deficiency
Immune mediated hemolytic anemia
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.
Which of these treatments might be used for a dog with immune-mediated hemolytic anemia?
Enrofloxacin
Azathioprine
Maropitant
Piroxicam
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.
A 6-week old male intact puppy has presented to your clinic after being bitten 4 days ago. On physical examination, there is a moderate amount of purulent discharge noted from the bite wound on the left antebrachium. The wound is approximately 2 cm in length. Which antibiotic is LEAST appropriate for this patient?
Doxycycline
Cephalexin
Penicillin
Metronidazole
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.
A 3-year-old spayed female Rhodesian Ridgeback presents for mild pruritus and skin lesions. Upon examination, you notice diffuse papules and occasional pustules along the dorsal trunk. You conclude that the patient has folliculitis. Which of the following most commonly causes pustule formation and folliculitis such as this?
Sarcoptes scabiei
Staphylococcus
Trichodectes
Chyletiella
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.
A 7-year-old pit bull mix presents with these skin lesions (see image) and mild pruritus. The owner has recently started him on a hypoallergenic diet. You perform a skin cytology and observe neutrophilic inflammation. What is a top differential for this condition?
Cheyletiella
Sarcoptes
Dermatophytosis
Bacterial pyoderma
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.
A chocolate lab presents for routine wellness examination and vaccinations. Your only abnormal finding on physical examination is seen here (see image). What treatment would you NOT recommend?
Dips
Manual removal
Pour on
Burn off
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.
A 4-month old intact male Collie presents for severe dermatitis along his nose and ears (see image). The areas are sensitive on palpation but not pruritic. No other areas are affected. Skin scraping and cytology are negative for mites or bacteria. Fungal culture is negative. Anti-nuclear antibody tests are ordered and are also negative. How do you educate the owner based on your presumptive diagnosis?
Biopsy and culture are necessary, long-term therapy often needed.
Biopsy and culture are necessary, short-term therapy often needed.
The disease is not curable; euthanasia should be discussed.
The disease is familial, and is often cyclic and will regress.
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.
A 2-year old female spayed Dachshund presents for further evaluation as a result of a mass on the pinna noted by the owner. On physical exam, the only abnormality noted was this mass. Cytology is consistent with a histiocytoma. Which of the following is the most reasonable treatment option?
Cryotherapy
Chemotherapy using lomustine
Radical surgical excision
Radiation therapy
Benign Neglect
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.
Which of the following clinical signs may be seen with discoid lupus erythematosus (DLE) in dogs?
Hyperpigmentation of the ventral abdomen
Depigmentation of the nasal planum
Symmetrical truncal alopecia
Swollen, painful joints
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).
A 5-year-old Doberman presents for chronic pruritus and recurrent bacterial skin infections. The patient has been on a 4-week course of Cephalexin and continues to get new skin lesions despite this treatment. You suspect methicillin resistance and recommend a skin culture. The owner declines a culture and would like you to select another antibiotic empirically. Which antibiotic would be the best choice considering side effects and efficacy?
Trimethoprim-sulfa
Chloramphenicol
Cefpodoxime (Simplicef)
Clindamycin
Cefovecin (Convenia)
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.
An 8-year old female Chow Chow presents to you for difficulty eating. On oral exam, you see a 3 cm mass in the caudal maxilla. You are unable to obtain a fine needle aspirate because of the mass’s location but you detect an enlarged mandibular lymph node and aspirate it. A representative field from the aspirate is shown in the image below. In addition to surgery (+/- radiation), which of the following is an APPROVED treatment option for this disease that you would mention to the owner?
Doxorubicin
Palladia
ONCEPT vaccine！
Mitoxantrone
Vincristine
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.
The following image shows a 3-D CT reconstruction of a 7-year old mixed breed small dog with a history of pain on opening the mouth for the past 2 weeks. The patient initially received a dental prophylaxis and cleaning under the assumption that the pain was related to moderate dental disease. When the pain persisted skull radiographs were performed and showed evidence of a mixed proliferative and lytic mass at the proximal aspect of the vertical ramus. What muscle attaches to this region?
Pterygoid
Digastricus
Masseter
Temporalis
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.
The 3-year old English Setter in the photos presents to you with severe pruritus affecting the face, axillary, and inguinal regions as well as the dorsal aspect of the paws. After a careful history and physical examination, you suspect the dog has atopy. What type of hypersensitivity (HPS) and what class of immunoglobulin are MOST IMPORTANT in the pathogenesis of atopic dermatitis in dogs?
Type IV HPS, IgE
Type IV HPS, IgA
Type I HPS, IgE
Type I HPS, IgA
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.”
A 1-year old bull dog mix presents for physical exam before breeding. Her physical exam is unremarkable with the exception of the abnormality seen in this image (prolapsed gland of the nictitans). What is the best method of treatment, and would you recommend breeding this bitch?
Surgical removal will be curative. Consider not breeding.
Surgical removal will be curative. Continue with breeding schedule.
Surgical replacement will be curative.
Continue with breeding schedule.
Surgical replacement will be curative. Consider not breeding.
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.
An 8-year old mixed breed male neutered dog presents with a several-month history of lethargy, hair loss, and greasy skin. The patient’s face, feet, and tail are not clinically affected and he is not pruritic. What is the most likely cause of the hair loss?
Sarcoptes
Flea allergy
Malignant melanoma
Endocrinopathy
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.
All of the following drugs are appropriate in the management of tachycardia associated with this arrhythmia in small animal patients except:
Isoproterenol
Atenolol
Digoxin
Procainamide
Diltiazem
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.
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: 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.
A 15-year old male castrated terrier mix presents for cough and rapid, shallow breathing. You auscult a grade IV/VI left apical holosystolic murmur and crackles throughout both lung fields. An echocardiogram is performed, shown here. What findings are shown on this echocardiogram?
Tricuspid valve endocarditis
Mitral valve prolapse
Pulmonic stenosis
Left ventricular concentric hypertrophy
Right ventricular concentric hypertrophy
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.
A 11-year old male castrated Golden Retriever presents for collapse with muffled heart sounds on examination. You ultrasound the heart and obtain the following image; the right atrium (RA) and right ventricle (RV) are labeled. A large mass is seen in the right atrioventricular groove with pericardial effusion. What is the likely diagnosis?
Hemangiosarcoma
Lymphoma
Chemodectoma
Idiopathic pericardial hemorrhage
Pulmonary adenocarcinoma
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.
A 9 year old female spayed black Labrador Retriever presents to your clinic with the complaint of collapse and lethargy. On exam, the dog is subdued but responsive with a temperature of 100.9F (38.3 C), heart rate of 170 beats per minute, and respiratory rate of 40 breaths per minute. You perform chest radiographs which are shown below. A CBC shows a hematocrit of 31% (35-57%), neutrophil count of 6,275/ul (2,900-12,000/ul), monocyte count of 984/ul (100-1,400/ul) and eosinophil count of 630/ul (0-1,300/ul). What is the treatment of choice?
Terbutaline
Melarsomine
Broad spectrum antibiotics
Furosemide
Pericardiocentesis
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.
A 5-year old Pug in an animal shelter dies after experiencing cough, exercise intolerance, and dyspnea as well as ascites and hepatomegaly secondary to congestive heart failure. You perform a necropsy and find the parasite shown in the image below residing primarily in the pulmonary artery. How is this parasite transmitted?
Mosquito
Aerosol
Tick
Fecal-oral
Flea
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.
This ECG recording (bottom recording) is from a 10-year old miniature poodle with a history of heart disease that is untreated. She presented for a 3-day history of diarrhea and decreased appetite. On physical examination you auscult a grade Ill/VI heart murmur and clear lung sounds. There are no obvious pulse deficits palpated. What is the appropriate treatment for this arrhythmia?
Give the patient a bolus of lidocaine and begin continuous infusion for twelve hours and then try to wean off the lidocaine
Begin the patient on oral mexiletine and recheck an ECG strip in 5 days
No anti-arrhythmic therapy is necessary at this time
Give the patient an intravenous injection of furosemide and begin oral administration of furosemide
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.
A 6-year old female spayed Beagle presents for lethargy. On exam you detect a heart rate of 25 beats per minute and record an ECG, which is shown here. What is the treatment of choice?
Pacemaker implantation
Atropine administered intramuscularly
Doxycycline
Furosemide
Sotalol
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.
A 12-year old female Dalmatian has a Holter monitor placed for an arrhythmia heard on exam. The following trace is from that monitor; similar abnormalities were seen frequently throughout the 24hrs. What is your treatment recommendation for this arrhythmia?
Mexiletine
Diltiazem and furosemide
Amlodipine
Pimobendan
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.
A 9 year old female spayed Greyhound presents to you for evaluation of a cough of 2 weeks duration and respiratory difficulty. The owner reports that the dog collapsed while chasing her ball yesterday. On your exam, heart sounds are quiet and the dog’s mucous membranes appear pale. You elect to take thoracic radiographs which are shown below. What is an appropriate treatment?
Atenolol
Measure taurine levels
Heartworm test
Pericardiocentesis
Furosemide
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.
This is an ECG recording of a 9-year old male castrated Golden Retriever that had a bleeding splenic mass surgically removed approximately 4 hours ago. The heart rate is currently 186 bpm. The patient received 0.08mg/kg of hydromorphone approximately 45 minutes ago. PCV is currently at 24 (normal 33-58%). What is the best treatment option?
Provide a lidocaine bolus followed by a continuous infusion of lidocaine
This patient is severely anemic and requires a blood transfusion immediately
This is not an alarming heart rate or ECG and requires no treatment
The patient is having breakthrough pain due to the low dose of hydromorphone and should be given an adequate dose of hydromorphone
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.
A 7-year old male intact Chesapeake Bay Retriever presents to your clinic with the presenting complaint of an intermittent cough. On exam, the dog is bright and alert with a temperature of 100.5F (38.1 C), heart rate of 110 beats per minute and respiratory rate of 30 breaths per minute. You perform chest radiographs which are shown below. A CBC shows a hematocrit of 39% (35-57%), neutrophil count of 8,659/ul (2,900-12,000/ul), monocyte count of 984/ul (100-1,400/ul) and eosinophil count of 1,980/ul (0-1,300/ul). What is the treatment of choice for the most likely diagnosis?
Pericardiocentesis
Immiticide (Melarsomine)
Enrofloxacin
Furosemide
Terbutaline
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.
A 10-year old male mixed breed dog presents to you for intermittent cough since the owner obtained the dog from a rescue organization. On your physical exam, the dog is fearful and underweight (body condition of 2/9). No othe significant abnormalities are noted. Your complete blood count shows:
hematocrit of 33% (35-57%)
platelets- 270,000/ul ( 211,000-621,000/ul)
WBC- 11,500/ul (5,000-14,100/ul)
neutrophils 6,500/ul (2,900-12,000/ul)
monocytes 1,200/ul (100-1,400/ul)
eosinophils 3,800/ul (0-1,300/ul)
lymphocytes 1,500/ul (400-2,900/ul
Chemistry values are:
BUN 12 mg/dl (8-28 mg/dl)
creatinine 0.7 mg/dl (0.5-1.7 mg/dl)
glucose- 99 mg/dl (76-119 mg/dl)
globulin- 6.7 g/dl (2.7-4.4 g/dl) albumin- 2.4 g/dl (2.3-32 g/dl)
ALT-51 U/L (10-109 U/L)
You take the thoracic radiographs shown here.
What is the most important additional diagnostic test that you should recommend to the owner?
Urine cortisol: creatinine ratio
Serum protein electrophoresis
Trypsin-like immunoreactivity (TLI)
Serum lead levels
Fecal flotation
Heartworm antigen test
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.
Dutchess, a five year old female spayed Labrador Retriever, presents to the emergency clinic with a 2 day history of lethargy, inappetance, diarrhea, and vomiting. On physical exam, she is painful on abdominal palpation, 7% dehydrated, and febrile.
Abdominal radiographs were performed and showed evidence of ascites and gas distension in the small intestines.
Preliminary blood work showed a PCV of 32% (35-57 %), TP 2.2 g/dl (5.4-7.5 mg/dl), glucose 57 mg/dl (76-119 mg/dl), Na 140 mEq/L (142-152 mEq/L), Cl 115 mEq/L (110-124 mEq/L), K 3.9 mEq/L (3.9-5.1 mEq/L). Given the surgical findings (see image below) what is the likely abdominal fluid glucose level?
- At least 20 mg/dl greater than the blood glucose
- Approximately the same as the blood glucose
- At least 10 mg/dl less than the blood glucose
- At least 10 mg/dl greater than the blood glucose
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.
A 6-month old Chocolate Labrador presents for limping and failure to gain weight. He is housed in an outdoor kennel with other hunting dogs. He is fed a large breed dry puppy food. He received his puppy shots at 8, 12, and 16 weeks old. He is quiet, alert, and responsive. His body condition score is 3/9, with rib exposure and poor fat deposition. His mucous membranes are pale pink, with a capillary refill time of 2 seconds. His heart and lungs auscult normally. No abnormalities are felt on abdominal palpation. He is an intact male, and both testicles are descended. The only abnormalities are the pads of his two front feet and left hind foot (see image) that he chews at frequently. What is diagnostic test of choice?
- Biopsy
- Fecal float
- Radiographs
- CBC and chemistry panel
- PCV and TP
- Skin scraping
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.
On the morning of a beautiful summer day, a five-year old, male German Pointer played unattended in the backyard garden. During the following 24 hours the right side of the dog’s face became swollen as seen in the image below. The dog developed urticaria and became lethargic, unable to walk and vomited several times. Which of the following are the best treatment options for the likely condition?
- Diazepam, methocarbamol, and non-steroidal anti-inflammatories
- Furosemide, oxygen, and nitroglycerin
- Drain the swelling, administer antibiotics
- Induce vomiting, administer activated charcoal, intravenous fluids
- Antihistamines, corticosteroids, and epinephrine
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.
