Free DVM Doctor of Veterinary Medicine Large Animal Medicine Questions and Answers — Questions and Answers
Question 1: A 4-year-old female Boer goat presents with acute neurological signs including stargazing, circling, and apparent blindness. The owner reports a recent change in feed, incorporating a higher concentration of grain. What is the most likely diagnosis and appropriate immediate treatment?
- Listeriosis; high-dose penicillin
- Polioencephalomalacia (PEM); injectable thiamine (Vitamin B1) (Correct answer)
- Caprine Arthritis Encephalitis (CAE); supportive care
- Tetanus; tetanus antitoxin and wound debridement
Correct answer: Polioencephalomalacia (PEM); injectable thiamine (Vitamin B1)
Polioencephalomalacia (PEM) is a neurological disease in ruminants often associated with a thiamine (Vitamin B1) deficiency. This deficiency can be induced by high-grain diets, which alter rumen microflora and can lead to the production of thiaminase enzymes that destroy thiamine. The clinical signs of apparent blindness, stargazing, and circling are classic for PEM. Prompt administration of high doses of injectable thiamine is the treatment of choice and can be diagnostic, often resulting in rapid improvement if administered early.
Question 2: A producer of a large swine finishing operation reports an increase in post-weaning mortality. Affected pigs are 8-12 weeks old and exhibit progressive weight loss ('wasting'), respiratory distress, and visibly enlarged inguinal lymph nodes. Several pigs also have diarrhea and pale skin. Which of the following pathogens is the most likely primary cause of this syndrome?
- Lawsonia intracellularis
- Streptococcus suis
- Porcine circovirus type 2 (PCV2) (Correct answer)
- Actinobacillus pleuropneumoniae
Correct answer: Porcine circovirus type 2 (PCV2)
The clinical signs described—progressive weight loss (wasting), respiratory disease, and generalized lymphadenopathy in post-weaning pigs—are the hallmark presentation of Porcine Circovirus Associated Disease (PCVAD), caused by Porcine Circovirus type 2 (PCV2). This condition was formerly known as Postweaning Multisystemic Wasting Syndrome (PMWS). While other pathogens can cause individual signs, the combination of wasting, respiratory signs, and significant lymph node enlargement is most characteristic of PCVAD.
Question 3: You are called to a dairy farm to examine a cow that calved 6 hours ago. The owner reports a large, reddish mass protruding from the vulva. Upon examination, you identify a complete uterine prolapse with the caruncles visible. The cow is standing but straining. Which of the following is the most critical first step in managing this case?
- Administer a high dose of oxytocin to cause uterine involution.
- Immediately attempt to manually replace the uterus using firm pressure.
- Administer a caudal epidural anesthetic. (Correct answer)
- Start intravenous fluids and broad-spectrum antibiotics.
Correct answer: Administer a caudal epidural anesthetic.
The most critical first step in managing a uterine prolapse is to administer a caudal epidural anesthetic. This will stop the cow's straining (tenesmus), which is essential for successful replacement of the uterus and prevents further trauma to the tissue. Attempting replacement without an epidural is often futile and can lead to uterine rupture or other complications. While fluid therapy and antibiotics are important supportive measures and cleaning/reducing edema of the uterus is necessary, controlling the straining via anesthesia must be done first.
Question 4: A group of recently weaned beef calves arrives at a feedlot after a long transport. Within 10 days, several calves develop a fever (105°F), depression, nasal discharge, and a moist cough. This complex, multifactorial respiratory disease is commonly referred to as Bovine Respiratory Disease (BRD) or 'shipping fever'. Which of the following is NOT a primary viral pathogen typically associated with initiating BRD complex?
- Infectious Bovine Rhinotracheitis (IBR) virus
- Bovine Viral Diarrhea (BVD) virus
- Bovine Spongiform Encephalopathy (BSE) agent (Correct answer)
- Parainfluenza-3 (PI3) virus
Correct answer: Bovine Spongiform Encephalopathy (BSE) agent
Bovine Respiratory Disease (BRD) is a complex initiated by stress and primary viral infections, which then allows for secondary bacterial pneumonia. Common viral culprits include Infectious Bovine Rhinotracheitis (IBR, a herpesvirus), Bovine Viral Diarrhea (BVD) virus, Parainfluenza-3 (PI3) virus, and Bovine Respiratory Syncytial Virus (BRSV). Bovine Spongiform Encephalopathy (BSE) is a progressive, fatal neurological disease caused by a prion, not a virus, and is not involved in the pathogenesis of BRD.
Question 5: A 10-year-old Quarter Horse gelding presents with a cresty neck, generalized obesity (BCS 8/9), and a history of recurrent laminitis. You suspect Equine Metabolic Syndrome (EMS). Which diagnostic test is considered the most sensitive for confirming insulin dysregulation associated with this condition?
- Baseline cortisol measurement
- Thyroid-releasing hormone (TRH) stimulation test
- Oral sugar test (OST) (Correct answer)
- Complete blood count (CBC)
Correct answer: Oral sugar test (OST)
Equine Metabolic Syndrome (EMS) is characterized by insulin dysregulation (ID), which is a key factor in the development of laminitis. While baseline insulin and glucose can be used as screening tools, they can be affected by stress or recent meals. The Oral Sugar Test (OST) is a dynamic test that is more sensitive for diagnosing ID. It involves administering a sugar solution (like Karo syrup) orally and measuring the insulin response over time, providing a more accurate assessment of the horse's ability to handle a carbohydrate challenge.
Question 6: A beef cow on a lush legume pasture presents with severe abdominal distension on the left side, dyspnea, and grunting. The distension is firm and non-reducible with a stomach tube. You diagnose frothy (pasture) bloat. Which of the following is the most appropriate treatment?
- Trocarization of the right paralumbar fossa to release free gas.
- Administration of an anti-foaming agent, such as poloxalene, via stomach tube. (Correct answer)
- Intravenous administration of calcium gluconate to stimulate rumen motility.
- Oral administration of a large volume of cold water to 'shock' the rumen.
Correct answer: Administration of an anti-foaming agent, such as poloxalene, via stomach tube.
Frothy bloat, or primary ruminal tympany, occurs when fermentation gases are trapped in a stable foam, which cannot be eructated. Unlike free-gas bloat, passing a stomach tube or using a trocar is often ineffective because the foam will quickly block the opening. The definitive treatment is to administer an anti-foaming (surfactant) agent, like poloxalene or mineral oil, directly into the rumen via a stomach tube. This agent breaks down the surface tension of the foam, destabilizing it and allowing the gas to coalesce and be eructated.
Free DVM Doctor of Veterinary Medicine Large Animal Medicine Questions and Answers
A 4-year-old female Boer goat presents with acute neurological signs including stargazing, circling, and apparent blindness.
The owner reports a recent change in feed, incorporating a higher concentration of grain.
What is the most likely diagnosis and appropriate immediate treatment?