DVM Large Animal Medicine 4 — Questions and Answers
Question 1: Which of the following best describes the pathophysiology of 'hardware disease' (traumatic reticuloperitonitis) in cattle?
- Bacterial infection of the rumen wall
- Ingested metallic foreign body penetrates the reticulum wall causing peritonitis (Correct answer)
- Volvulus of the reticulum on its mesentery
- Viral inflammation of the forestomachs
Correct answer: Ingested metallic foreign body penetrates the reticulum wall causing peritonitis
Hardware disease occurs when ingested metal (wire, nails) penetrates the reticulum, causing localized or diffuse peritonitis; a magnet placed in the reticulum is the standard prevention.
Question 2: A foal is born to a mare with a history of producing isoerythrolysis-affected foals. Which blood type incompatibility is MOST commonly involved in equine neonatal isoerythrolysis?
- Aa and Qa blood group antigens (Correct answer)
- Cc and Ee antigens
- DEA 1.1 antigen
- Neonatal alloimmune thrombocytopenia
Correct answer: Aa and Qa blood group antigens
Equine neonatal isoerythrolysis most commonly involves Aa and Qa blood group antigens, where an Aa- or Qa-negative mare becomes sensitized and produces antibodies passed through colostrum.
Question 3: A cow presents with sudden blindness, opisthotonus, and pressing behavior. CSF analysis shows glucose depletion and elevated lactate. What is the most likely diagnosis?
- Listeriosis
- Polioencephalomalacia (cerebrocortical necrosis) (Correct answer)
- Bovine herpesvirus-1 encephalitis
- Lead toxicosis
Correct answer: Polioencephalomalacia (cerebrocortical necrosis)
Polioencephalomalacia results from thiamine deficiency or sulfur toxicosis causing cerebrocortical necrosis, presenting with blindness, ataxia, and opisthotonus; it responds to IV thiamine.
Question 4: During a pre-purchase examination of a horse, bilateral tarsal periarticular remodeling is noted on radiographs with evidence of distal intertarsal and tarsometatarsal joint fusion. This is consistent with which condition?
- Osteochondrosis dissecans of the tarsus
- Bog spavin
- Bone spavin (distal tarsal osteoarthritis) (Correct answer)
- Curb
Correct answer: Bone spavin (distal tarsal osteoarthritis)
Bone spavin refers to osteoarthritis of the distal tarsal joints (centrodistal and tarsometatarsal), which can progress to bony fusion; it is a common cause of hindlimb lameness in horses.
Question 5: Which of the following best describes the mechanism of ionophore toxicity (e.g., monensin) in cattle?
- Inhibition of acetylcholinesterase causing cholinergic crisis
- Disruption of mitochondrial cation transport leading to cardiac and skeletal muscle necrosis (Correct answer)
- Competitive inhibition of vitamin K epoxide reductase
- Direct hepatotoxicity via lipid peroxidation
Correct answer: Disruption of mitochondrial cation transport leading to cardiac and skeletal muscle necrosis
Ionophores disrupt mitochondrial sodium/potassium transport, causing energy depletion and cell death in cardiac and skeletal muscle, leading to myopathy and heart failure.
Question 6: A goat kid presents at 3 days of age with bloody diarrhea and sudden death of littermates. Gram stain of intestinal content shows large gram-positive rods. Which pathogen is most likely responsible?
- Cryptosporidium parvum
- Rotavirus
- Clostridium perfringens type C (Correct answer)
- Escherichia coli K99
Correct answer: Clostridium perfringens type C
Clostridium perfringens type C produces beta-toxin causing hemorrhagic enteritis and rapid death in neonatal ruminants; large gram-positive rods in intestinal content support this diagnosis.
Question 7: A Standardbred trotter is presented for bilateral hindlimb weakness and muscle wasting. EMG reveals abnormal spontaneous activity in epaxial muscles. PSSM-2 testing is negative. Which condition should be considered?
- Equine degenerative myeloencephalopathy (EDM)
- Equine motor neuron disease (EMND) (Correct answer)
- Hyperkalemic periodic paralysis (HYPP)
- Equine protozoal myeloencephalitis (EPM)
Correct answer: Equine motor neuron disease (EMND)
Equine motor neuron disease causes lower motor neuron signs with muscle atrophy, abnormal EMG, and is associated with vitamin E deficiency; retinal pigment changes are pathognomonic.
DVM Large Animal Medicine 4
Which of the following best describes the pathophysiology of 'hardware disease' (traumatic reticuloperitonitis) in cattle?