Week 4 - March 3 Day 2

Question 1

What is the facial nerve responsible for? Damage to this nerve results in?

Answer 1

Provides motor innervation to the muscles of facial expression. Damage to this nerve may result in:
- Inability to blink
- Muzzle deviation
- Ear droop
- Lack of nostril flare
- Loss of menace and palpebral response

Question 2

What is the oculomotor nerve responsible for?

Answer 2

Provides motor innervation to the dorsal, medial, and ventral rectus muscles. Additionally, this nerve innervates the palpebral levator, which is responsible for raising the upper eyelid.

Question 3

What is the trochlear nerve responsible for?

Answer 3

The trochlear nerve innervates the dorsal oblique muscle of the eyeball. Injury to this nerve = dorsomedial strabismus.

Question 4

What is the trigeminal nerve responsible for?

Answer 4

Provides sensation to most of the face and also motor innervation to the muscles of mastication.

Question 5

What is the abducens nerve responsible for?

Answer 5

Motor innervation to the lateral rectus and part of the retractor bulbi muscles.

Question 6

Topic: African Horse Sickness

1. How is this disease transmitted?
2. Where is this disease endemic to?
3. What are the clinical signs?
4. How is it diagnosed?
5. How is it treated?
6. How can this disease be prevented?

Answer 6

African horse sickness (AHS) is a viral disease of equids that is transmitted by insects, primarily Culicoides.
African horse sickness is endemic in sub-Saharan Africa and outbreaks have periodically extended to the Middle East and southern Spain. The primary and biological vector is Culicoides but the virus may also be transmitted by mosquitoes. The virus has been isolated from certain ticks but arthropod transmission is not believed to play a significant role.
Clinical signs of AHS typically develop 5-7 days after infection and begin with fever and conjunctivitis.
Some animals may recover but many go on to develop the pulmonary and/or cardiac forms of AHS.
The pulmonary form consists of acute respiratory distress, coughing, sweating, and foaming from the nostrils; this form is usually fatal. The cardiac form consists of edema of the head and neck as well as abdominal pain and depression. A characteristic sign is swelling in the indentation above the eyes (also referred to as swelling of the supraorbital fossa). About 50% of animals with the cardiac form die from heart failure while the rest gradually recover after about one week.
Diagnosis can often be made based on history of exposure to endemic areas, clinical signs and lesions but must be confirmed by viral isolation and/or serology. There is no effective treatment and prevention/control can be accomplished by vector control and vaccination. There are multiple serotypes of virus and animals immunized against certain serotypes are still susceptible to others. In an outbreak situation, affected horses should be removed/euthanized and remaining horses should be vaccinated with a polyvalent vaccine until the specific serotype can be determined and then animals should be revaccinated with the corresponding vaccine.
For importing equids from Africa, a 2 month quarantine is required and then horses must test free of virus. Presence of antibodies does not disqualify a horse from importation. Because of the vector-borne nature of the disease, it is recommended that planes flying from endemic areas be sprayed with insecticides on arrival to disease-free countries.

Stable all horses in insect-proof housing, particularly at night because the disease is transmitted primarily by Culicoides flies

Question 7

Topic: Equine Recurrent Uveitis

1. This is also referred to as?
2. List the etiologies.
3. Recurrent bouts of uveitis can lead to?
4. Recurrent uveitis is the most common cause of ?
5. How should this condition be treated?

Answer 7

Equine recurrent uveitis (also referred to as periodic ophthalmia, recurrent iridocyclitis, and moon blindness) is common in horses. There are many proposed causes for this condition, but it is thought to usually be from infection (Onchocerca, Leptospira, or Borrelia) or immune-mediated processes. Because recurrent bouts of uveitis can lead to serious problems including cataracts, lens luxation, and glaucoma, it should be treated aggressively with topical and systemic anti-inflammatory drugs and topical atropine to prevent synechiae and ciliary spasm.
Systemic antibiotics are usually not indicated unless the horse is febrile or an infectious cause is identified.

Question 8

How can you tell the difference between a central vs peripheral vestibular lesion?

Answer 8

Peripheral vestibular dysfunction causes signs of head tilt, nystagmus, circling and asymmetric ataxia with preservation of strength. The head tilt is toward the affected side as is circling towards the lesion.

Comparatively, central vestibular disease has similar clinical signs but general conscious proprioceptive deficits, weakness and cranial nerve deficits may also be present along with depression.

Question 9

Describe the pathophysiology of Intraosseous desmitis in horses.

Answer 9

Intraosseous desmitis occurs when there is inflammation of the intraosseous ligament, located between the 3rd metacarpal or metatarsal bone with the small metacarpal or metatarsal bones.

Periostitis occurs when there is new bone formation along the splint bones or small metacarpals or metatarsal due to repetitive concussion, excessive training, poor conformation, or improper shoeing.

Do xrays to rule out a fracture of the splint bones.

Question 10

What is the dental formula for a horse?

Answer 10

2(I3/3 C1/P P3-4/3 M3/3)

Horses may have 3 or 4 maxillary premolars

Question 11

What AV blocks are considered a normal finding in horses?

Answer 11

First and second degree AV blocks are normal and are usually due to high vagal tone.

Question 12

What is the definitive host of Dictyocaulus arnfeldi?

Answer 12

Donkeys!!!!

Question 13

You are called to a horse ranch that has an ongoing problem controlling infection and transmission of Streptococcal infections (Streptococcus equi subsp. equi) among its horses. You attempt to identify carriers by collecting wash samples from the guttural pouch since this is the most common place that horses harbor the organism. On endoscopy, you detect several hard, smooth, stone-like structures within the guttural pouch. Which of the following is the most important intervention?

Answer 13

These objects are chondroids which are hardened pus filled concretions with bacteria. They most commonly occur when horses develop guttural pouch empyema which is an accumulation of purulent exudate in the guttural pouch due to mucosal infection or drainage from the retropharyngeal lymph nodes from Streptococcus equi subsp. equi (Strangles). The persistence of pus provides a refuge for the bacteria and allows for continued bacterial shedding. When exudate persists, it can become increasingly dense, forming solidified concretions that are difficult to extract and serve as a source for continued prolonged shedding of the organism.
To reduce shedding and transmission, these chondroids should be removed and the guttural pouch should be flushed and infused with 5 million units of penicillin G in 3% gelatin. Chondroids can be removed surgically or via endoscopic basket removal.
In addition, these horses should be treated with penicillin G intramuscularly for 7 days, isolated for 30 days, and then retested with 3 consecutive series of nasopharyngeal swabs and culture. Animals that remain positive should go through a repeat treatment and culture cycle
As of 2017, S. equi is a reportable disease in all states within the US.

Question 14

Vitamin K3 should NEVER be given to horses because it is?

Answer 14

Nephrotoxic

Question 15

How would you tx warfarin toxicosis in a horse?

Answer 15

Vitamin K1 subq every 6 hrs
1-2 L of Plasma to replenish clotting factors

Question 16

Which of these drugs has the greatest potential for causing acute renal failure in the horse?

Neomycin
Dexamethasone
Diphenhydramine
Oxytetracycline
Xylazine

Answer 16

The correct answer is neomycin. Aminoglycosides are one of the most common causes of renal tubular nephrosis and acute renal failure. Of the aminoglycosides, neomycin is probably the most nephrotoxic, followed by gentamicin, amikacin, and streptomycin. The other big class of nephrotoxic drugs is non-steroidal anti-inflammatory drugs.

Question 17

A horse gets into cow feed that contains the ionophore, monensin. What is your biggest concern?

Answer 17

Cardiotoxicity

Monensin is a coccidiostat used to increase productivity in cattle. Horses are much more susceptible to toxic effects of monensin than cattle and mistakes in feeding or
accidental access to cattle feed can lead to toxicity. Monensin toxicity results in myocardial necrosis and development of dilated cardiomyopathy in horses. Clinical signs include progressive respiratory distress, heart murmur, weakness, and hypovolemic shock. Acutely, mild colic and diarrhea can occur as well but is less of a concern than the cardiovascular effects.

Question 18

Topic: Equine Repro

1. What is the average equine gestation length?
2. What type of estrous cycle do horses have?
3. When do horses naturally start cycling?
4. When is artificial lighting used?

Answer 18

1. 330-365; Average is 345
2. Seasonally polyestrous
3. April or May
4. Artificial lighting is used starting in Mid-Dec=ember to promote estrus in mid- February

Question 19

When performing a fundic exam on a horse with uveitis, you notice multiple dark dots on the tapetum as shown here. What do these dots most likely indicate?

Answer 19

The equine tapetum is penetrated by small choroidal vessels that appear as dark dots. These are sometimes affectionately referred to as the stars of Winslow.

Question 20

Melanomas occur in up to 80% of gray horses. They occur most commonly on the perineum and tail base but can arise anywhere on the body. Most melanomas of gray horses are benign with varying degrees of invasiveness. They have the potential to develop into malignant tumors. Treatment includes surgery or cryosurgery. Horses that develop one melanoma are predisposed to developing others in the future.

Question 21

If a horse is in seasonal anestrus, which of these is the most effective means of hastening the start of the breeding season?

Provide atifealighe fort6 hoursper day 6o days pierto the start of breeding

Provide artificial light for 12 hours per day 60 days prier to the start of breeding

Provide artificial light for 12 hours per day 30 days prior to the start of breeding

Provide artificial light for 16 hours per day 30 days prior to the start of breeding

Answer 21

The correct answer is to provide 16 hours of artificial light 60 days prior to the start of breeding. To get a horse to transition out of seasonal anestrus, you can gradually increase the amount of light to 15-16 hours per day to initiate ovarian activity. It usually takes at least 60 days until physiologic breeding will occur. There are hormonal methods to promote cycling, but they are less consistent than altering light.

Question 22

Topic: PPID In Horses

1. What is the pathogenesis of PPID?

Answer 22

1. This condition is a result of hypertrophy, hyperplasia,
   and micro- or macroadenoma of the pituitary pars intermedia that secretes increased amounts of
   propiomelanocortin peptides. Adjacent pituitary tissues are compressed and secrete less of some other peptides. Data suggest that horses with this disease have hypothalamic dysfunction and decreased amounts of dopamine.

Question 23

What is the treatment for a persistent corpus luteum that will allow a return to estrus in a mare?
Gonadotropin-releasing hormone (GnRH) injection
Progesterone injection
Human chorionic gonadotropin (hCG) injection
PGF-2-alpha (prostaglandin) injection

Answer 23

PGF will cause lysis of the corpus luteum in mares if the corpus luteum is more than about 5 days old. If you are unsure how old the corpus luteum is, you can repeat the injection in about 7 days. This will allow a return to normal cycling.

Remember, injection of PGF may cause mild-moderate abdominal pain (colic, cramping) after administration.

Progesterone injection would not change things because the horse already has high levels of progesterone due to the persistent corpus luteum.

hCG stimulates ovulation, but if the horse has high progesterone from the corpus luteum, it will not exhibit a behavioral estrus. GRH would have similar effects.

Question 24

For neonatal isoerythrolysis to occur, what antigens does the sire and dam need to possess when they mate? Describe the pathophysiology

Answer 24

stallion positive for Qa and mare negative for Qa. For neonatal isoerythrolysis to occur, the mare must develop antibodies to the foal’s red blood cell antigens. Aa and Qa are the two antigens most frequently implicated in this condition. For this condition to occur, the foal must inherit the Aa or Qa antigen from the stallion, and the mare must be negative for the antigen (if she was positive, meaning she has the Qa antigen on her RBCs, she would not make antibodies against it).
Then, when the mare becomes exposed to the foal’s red blood cell antigens, she makes antibodies.
When she passes these antibodies to the foal through colostrum, an acute hemolytic event will occur in the foal. In most cases, the first time a mare has a foal with the antigen, she will not produce sufficient antibodies to cause severe damage to the foal. Therefore, this condition is usually seen in multiparous dams or in mares that have previously had a blood transfusion that exposed them to the red blood cell antigens.

Question 25

A 9 year old American Paint Horse presents to you for neurologic signs that have progressed over 3 days. You have asked the owner about the horse's vaccination history and find out that the horse is vaccinated against rabies but not other pathogens. The horse was previously depressed and anorectic, progressing to head pressing and circling, and the horse is now recumbent. You perform cerebrospinal fluid analysis and find CSF protein of 80 mg/d with a primarily mononuclear pleocytosis. Which of these is the most likely diagnosis? Equine protozoal myeloencephalitis Cerebellar abiotrophy Cervical vertebral malformation Eastern equine encephalitis Equine degenerative myelopathy

Answer 25

The keys to this question are that the horse is unvaccinated for EEE, has a progression of central nervous system signs over several days and characteristic CSF changes. Another reasonable differential would be rabies, particularly if the horse had not been vaccinated for it. Equine protozoal myeloencephalitis (or myelitis) is usually seen in 1-6 year old horses and is caused by Sarcocystis neurona. It should be suspected when a horse has asymmetric neurological signs, as it is a multifocal disease of the central nervous system. Cervical vertebral malformations and degenerative myeloencephalopathy are diseases seen primarily in horses under a year of age. Degenerative myelopathy causes a symmetrical ataxia. Cerebellar abiotrophy is usually observed in foals that are less than one year of age, particularly 1-6 months of age. It is mostly seen in Arabian, Oldenburg, and Gotland breeds. There is no treatment, and signs may be progressive. Diagnosis is based on a good history and clinical signs such as intention tremors, lack of a menace, hypermetria, and ataxia.

Question 26

A 3-year old steeplechaser horse presents to you for lameness. The owner reports that the horse developed a short-striding lameness of the left pelvic limb after an event and that the horse is reluctant to bear full weight on the left hind leg. On examination, you notice a prominent bump to the left of midline on the topline of the hindquarters (croup). What is the most likely diagnosis? Gonitis Upward fixation of the patella Sacroiliac luxation Ruptured peroneus tertius Stringhalt

Answer 26

This case describes the common clinical findings in sacroiliac luxation/subluxation in horses. Jumping horses are commonly affected. The short strided gait is consistent with but not specific for this condition. The raised croup differentiates sacroiliac luxation from some other options in this case. Upward fixation of the patella is not a traumatic condition as you should suspect based on the history here. It does cause a short strided gait and toe-dragging. The tell-tale sign of this condition is a hind limb in rigid extension that is unable to flex. Gonitis is a term indicating stifle arthritis that is nonspecific to the underlying cause. Stringhalt is involuntary flexion of the hind limb and is usually bilateral. Stringhalt is treated with lateral digital extensor tenectomy. A ruptured peroneus tertius is characterized by the ability to simultaneously extend the hock and flex the stifle.

Question 27

A beef cattle farm in the mountains of California is experiencing an abortion storm affecting about 50% of heifers. The abortions are occurring primarily in the last trimester. The cows appear healthy; some of the aborted fetuses have hepatosplenomegaly and generalized lymphadenopathy. A necropsy on one of the aborted fetuses shows lymphoid hyperplasia in the spleen and granulomatous inflammation in the liver. In the thymus, extensive macrophage infiltration into the medulla was seen as well as loss of cortical thymoctes. Fetal IgG was markedly elevated. Based on the likely diagnosis, which of the following measures would decrease the future incidence of this problem? Control of mosquitoes Expose heifers to endemic areas before breeding age Vaccinate heifers against bovine herpesvirus Control of Ponderosa pine trees Avoid feeding silage to heifers

Answer 27

This is the typical presentation for epizootic bovine abortion (EBA), also known as foothill abortion. The agent causing foothill abortion remains a subject of some investigation but a 2005 molecular study identified a novel deltaproteobacterium as being present in the Ornithodoros coriaceus tick vector and in DNA from fetal thymuses. With EBA, cows usually do not experience abortions again in later pregnancies and exposure to endemic areas before breeding age can also prevent abortions. Other control options may include control of the tick vector or prophylactic antibiotic use. You can lower your index of suspicion for bovine herpesvirus (Infectious bovine rhinotracheitis virus) because there is no respiratory disease seen in this case; abortions from herpesvirus occur throughout pregnancy and fetuses are typically autolyzed with foci of necrosis in the liver or no gross lesions. Ponderosa pine needle abortions occur in the last trimester but cows are often moribund after delivery and hemorrhage. There are usually no specific fetal lesions.

Question 28

What can be used to treat coccidiosis in calves?

Answer 28

Lasalocid, as well as monensin, amprolium, decoquinate, diclazuril and toltrazuril can be used daily to prevent coccidiosis in young ruminants; there is no vaccine.

Question 29

Insert photo of japanese yew

Question 30

Insert photo of oleander

Question 31

Both Japanese yew (Taxus cuspidata) and English yew (T. baccata) contain alkaloids called taxines that are highly toxic and depress myocardial conduction by blocking sodium movement through membranes. Collapse and sudden death are commonly seen when this plant is ingested, often when clippings are consumed by livestock. Oleander causes similar clinical scenarios.

Question 32

What is the cause of Alpha-Mannosidosis? The correct answer is genetic (autosomal-recessive). The condition is the result of a defect of the enzyme alpha-mannosidase and is seen in Murray gray, Simmental, Holstein, Galloway, and Angus cattle. The cleavage between N-acetyl glucosamine and mannose will not occur and the oligosaccharide will accumulate within the lysosomes of neurons, reticuloendothelial cells, and macrophages. The first sign at 1 month to 15 months of age will be a mild ataxia of the pelvic limbs after exercise. Other signs then develop, including hypermetria, aggressiveness, and intention head tremors. Most affected individuals will end up getting diarrhea and becoming recumbent and die within months after diagnosis.

Question 33

Most foodborne illness in the U.S. is caused by?

Answer 33

Viruses (Norwalk-like caliciviruses)

Question 34

Post-milking teat dips are not effective at preventing this type of mastitis in cows. Streptococcus agatactiae Mycoplasma bovis Escherichia coli Corynebacterium bovis Staphylococcus aureus The correct answer is Escherichia coli. This is an environmental contaminant and not a contagious organism. Pre-milking teat dips are useful for preventing such noncontagious diseases as E. coli, Enterococcus, and Streptococcus sp. other than S. agalactiae. Post-milking teat dips help prevent the spread of contagious pathogens such as Strep agalactiae from the skin into the streak canal and gland.

Question 35

You are in charge of a slaughter house and are asked about why so many of the culled dairy cattle in a recent shipment have liver abscesses (see photo) and what can be done about it. The abscesses result in a significant financial loss for the owner because the liver is condemned, and he is concerned. What is the cause? Rumen acidosis Traumatic reticuloperitonitis with hepatic involvement Liver fluke migration Black disease Foot abscesses showering bacteria to the liver

Answer 35

Dairy cattle which are fed a high concentrate diet should be gradually introduced to it. Even so, an additional dietary buffer may be needed. The herd veterinarian should check rumen pH on about 5 high-producing cows by needle stick of the rumen 2 to 3 hours after they are fed. If some fall below pH 5.5, additional sodium bicarbonate should be added to the ration. The low rumen pH causes rumenitis allowing bacteria to translocate through the mucosa and be filtered from the hepatic portal circulation by the liver, resulting in one or more hepatic abscesses. The key to picking rumenitis is that there are many culled dairy cattle coming in with this problem of hepatic abscess. If it were feet or hardware it would only occasionally lead to a liver abscess.

Question 36

You perform an exam on a calf that was born with a twin. The calf has an enlarged clitoris and an abnormally small ano-genital distance. What is your diagnosis?

Answer 36

A freemartin results from in utero exposure of the female to Mullerian-inhibiting hormone (also called anti-mullerian hormone or AMH) being secreted by the male. She is exposed via anastomosis between the two fetuses' chorioallantoic vessels. Lupine causes fetal arthrogryposis if ingested, and ponderosa pine needles induce late abortion if consumed.

Question 37

What is the significance of xanthochromia on a CSF tap?

Answer 37

The correct answer is evidence of prior hemorrhage. This is that yellow discoloration that can be seen for at least a week after bleeding in the CSF. A black discoloration would be diagnostic for melanoma.

Question 38

A 7-day old calf presents for further evaluation and supportive care due to an acute onset of watery diarrhea. On physical examination, the calf is markedly depressed, floppy, nonresponsive, and 10% dehydrated. Which of the following best describes this calf's state?

Answer 38

No matter what the causative agent, calves of this age with severe diarrhea develop hypovolemia, severe metabolic acidosis, which results in potassium leaving cells, and the calf becomes hyperkalemic (in plasma). The floppy calf is typical of an animal with severe metabolic acidosis (base deficit of 15 meq or more) and may also be hypoglycemic. This calf is also possibly septic, as bacterial translocation across the gut often occurs in very ill calves.

Question 39

Nitrate toxicosis causes methemoglobinemia, in which the blood appears chocolate brown. As a result, the oxygen carrying capacity and delivery is greatly reduced and the animal may die. Methylene blue is usually administered IV as a 1% to 4% solution, with a total dose of 4 to 15 mg/kg body weight to cattle, for treating nitrate toxicosis. Nitrates are found in high levels in many plants and some water sources. The nitrate is converted in the rumen to nitrite and then absorbed into the blood, which causes oxidation of the heme iron to the +3 ferric state (called methemoglobin). Methylene blue restores the iron in hemoglobin to its normal (reduced) oxygen-carrying state. This is achieved by providing an artificial electron acceptor for NADPH methemoglobin reductase (RBCs usually don't have one; the presence of methylene blue allows the enzyme to function at normal levels). The NADPH is generated via the hexose monophosphate shunt.

Question 40

Clostridium hemolyticum is now called?

Answer 40

Clostridium novyi Type D

Question 41

Locoweeds are of the genera Astragalus, Oxytropis, and Swainsona, and many species contain a chemical which inhibits alpha-mannosidases and causes widespread neurovisceral cytoplasmic vacuolation and emaciation, as well as abortion and nervous system abnormalities. They tend to grow in the arid west, and are often eaten when other forage becomes scarce. Horses can also be affected. *

Question 42

A recently freshened 4-year old Guernsey with a body condition score of 4/5 presents for decreased milk production, anorexia, and depression. On physical exam, she has a mild fever and is ketotic. No pings were auscultated during the physical exam and a rectal exam was unremarkable. What is the most likely diagnosis? Pyrrolizidine alkaloid toxicity Oleander toxicity Right displaced abomasum Fatty liver syndrome

Answer 42

The correct answer is fatty liver syndrome. Fat cows are more predisposed to fatty-liver syndrome when they encounter a negative energy balance. Shortly after parturition, their energy needs increase dramatically with lactation. Clinical signs are vague so you must be able to reach the answer by paying attention to the signalment. Further, an RDA will present with much more systemic signs and you will be able to hear a ping. PA toxicity and oleander toxicity are possible but less likely given the signalment and clinical signs. Remember, oleander is cardiotoxic and causes arrhythmias and PAs will cause chronic damage to the liver.

Question 43

The correct answer is hypochloremia, metabolic alkalosis, and hypokalemia. As a result of torsion, affected animals sequester HCl in the abomasum, get hypochloremia and metabolic alkalosis. Additionally, animals become dehydrated and try to maintain adequate blood pressure by conserving sodium through renal mechanisms. Because there is an alkalosis, potassium is sequestered even more than usual in cells leading to hypokalemia. Normally the kidney excretes some potassium because of the need to maintain an equal number of anions and cations in the urine. But when there is insufficient potassium available, in order to reabsorb sodium to maintain blood pressure, hydrogen ions are excreted rather than potassium. This results in acidic urine at the same time as metabolic alkalosis, a condition known as paradoxic aciduria.

Question 44

Silicate stones are the result of high intakes of silica in mature range grasses, combined with other factors such as dehydration. Struvites (ammonium, magnesium, and phosphate) tend to be found in feedlot animals receiving large amounts of grain. Calcium carbonate stones are most common in sheep grazing pastures high in calcium and oxalates.

Question 45

The owner of a nearby dairy calls to have a wound on his heifer inspected. The wound is located ventrally, on the brisket, and there are larvae feeding on the tissue. The wound is approximately 5cm in diameter and has now become 6 cm deep as a result of larval feeding. As you approach the cow, you see a large, metallic blue- green colored fly leaving the wound. What is your diagnosis?

Answer 45

The correct answer is Cochliomyia hominivorax. This fly is also known as the screwworm. Females lay hundreds of eggs at the edge of fresh wounds on the cow; the larvae hatch in approximately 24 hours. As the larvae eat the living tissue, they create a huge wound. Screwworm larvae then fall off and pupate, completing their life cycle in approximately 21 days. This fly is reportable!

Question 46

What is the most common early sign of lidocaine toxicity in dogs?

Answer 46

CNS depression In dogs, toxicity of lidocaine is manifest primarily as CNS signs. Drowsiness or agitation may progress to muscle twitching and convulsions at higher doses. This occurs before respiratory or cardiac depression. Hypotension may develop if an IV bolus is given too rapidly. Cats are more sensitive to lidocaine toxicity and may show cardiac suppression and CNS excitation.

Question 47

A 3-year old female intact Doberman presents to your clinic for a routine spay. The owner states she has not recently been in heat and has been healthy her entire life. Aside from a thorough physical examination and routine blood work, what additional diagnostic test should be performed prior to surgery?

Answer 47

Doberman Pinschers are predisposed to having von Willebrand's Disease (vWD). Specifically, Dobermans have increased incidence of have Type 1 vWD. In this type, there is a reduced presence of functional von Willebrand factor. This factor is crucial in initial clot formation and attracts platelets and allows them to bind to exposed subendothelium after injury. A buccal mucosal bleeding test should result in a clot in less than 4 minutes in normal dogs. An abnormal result warrants further investigation to confirm the presence of vWD in order to take the appropriate measures prior to surgery.

Question 48

What is the method of choice for diagnosing rabies?

Answer 48

The correct answer is direct fluorescent antibody test. There are no gross pathologic lesions associated with rabies. A diagnostic microscopic lesion is the visualization of Negri bodies. Most commonly they occur in the hippocampus in carnivores and Purkinje cells in herbivores. However, these are only seen 50% of the time. Immunohistochemistry allows strain differentiation and the ability to differentiate vaccine vs. wild-type. RT-PCR has been used on autolyzed brain tissue that is difficult to evaluate with fluorescent antibodies, but this is not the test of choice at this time. Direct FA is the current preferred method of diagnosis; it is both rapid and sensitive. Usually impressions of the medulla, cerebellum, and hippocampus are performed.

Question 49

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?

Answer 49

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.

Question 50

Nitrous oxide moves into closed gas spaces such as the intestines. As such, its use is contraindicated in bowel surgeries.

Question 51

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.

Question 52

The radiographs show dynamic collapse of the intrathoracic trachea, carina, and mainstem bronchi. There is a marked redundant tracheal membrane in the cervical region. The left atrium may be slightly enlarged but there is no evidence of left heart failure. Based on these findings, you should suspect that tracheal collapse is the cause of the dog's clinical signs. Treatment options include bronchodilators (i.e. theophylline, terbutaline), cough suppressants (hydrocodone, butorphanol), weight loss, and corticosteroids to control inflammation. In severely affected dogs, sedation may be necessary to break the cough cycle. Dogs should be kept away from smoke and environmental pollution. About 70% of dogs respond to medical management. Those that don't are sometimes treated with stents or tracheal rings, but neither repairs the underlying cartilaginous defect.

Question 53

A 3-year old female spayed Chocolate Labrador presents with pruritus. The owner reports that over the past year and half she has been licking and scratching her ventrum, paws, ears, and face, particularly in the summer. The dog is currently on a good flea control program. On examination, you find crusted papules, erythema, and alopecia at those sites. Which of the following interventions will be the most successful treatment for the most likely PRIMARY UNDERLYING ETIOLOGY of the dog's pruritus? Topical administration of fipronil and S-methoprene Oral cephalexin and twice weekly shampoos with a chlorhexadine-containing product A strictly controlled diet with a single novel protein and a single novel carbohydrate Hyposensitization injections based on intradermal skin test results

Answer 53

Based on the signalment, history, and physical exam findings, you should be most suspicious of atopic dermatitis (atopy). Atopy can occur in any aged dog but typically begins in dogs between 1.0 and 3 years of age. It frequently can be seasonal, in contrast to food allergy. Ultimately, atopy is frequently a diagnosis of exclusion made by ruling out flea and food allergy with measures such as strict flea control and an elimination diet. However, enough clues are given here, and the question specifically asks for the treatment for the most likely underlying etiology. Fipronil (Frontline) and S-methoprene are flea insecticidal therapies. The distribution of the lesions makes flea allergy less likely, and additional flea insecticides unwarranted. Cephalexin and chlorheadine shampoos are treatments for pyoderma; pyoderma can occur secondary to any allergic skin disease but is not the likely underlying etiology in this case.

Question 54

What is the BARF diet?

Answer 54

raw meat and bone diet risk of salmonella infection

Question 55

Propofol's most common adverse side effect is temporary apnea. You should always be prepared to intubate and ventilate a patient when administering propofol due to the potential for severe apnea. It is certainly not wrong to monitor blood pressure and heart rate to assess anesthetic depth and vital signs, even for a brief procedure; but by far, the most important thing to watch is respiration.

Question 56

The correct answer is increase in total peripheral resistance, increase in cardiac contractility, bronchodilation. Epinephrine is an alpha- and beta-adrenergic stimulant which causes peripheral vasoconstriction, increase in total peripheral resistance, increase in cardiac contractility and cardiac output, and bronchodilation. It is often used in cardiac arrests and anaphylactic shock. It is also found in some local anesthetic agents because of its vasoconstrictive effects, which prolongs effect of the anesthetic.

Question 57

Pyometra occurs during what phase of the canine estrus cycle?

Answer 57

The correct answer is diestrus. In diestrus, progesterone is the predominant hormone, and it promotes endometrial growth, suppresses myometrial activity, and inhibits leukocyte response to infection. This all predisposes the dog to development of pyometra.