NAVLE Canine Medicine and Surgery 5 — Questions and Answers
Question 1: A dog presents with a rapidly growing subcutaneous mass on the trunk. Fine needle aspirate shows granules that stain metachromatically with toluidine blue. What is the diagnosis and recommended initial treatment?
- Lipoma; surgical excision with narrow margins
- Mast cell tumor; wide surgical excision with 2-3 cm margins (Correct answer)
- Histiocytoma; conservative management as spontaneous regression occurs
- Sebaceous adenoma; CO2 laser ablation
Correct answer: Mast cell tumor; wide surgical excision with 2-3 cm margins
Mast cell tumors contain metachromatic granules and require wide surgical margins of 2-3 cm laterally and one fascial plane deep to reduce local recurrence.
Question 2: A 2-year-old female Weimaraner presents with recurrent urinary tract infections despite appropriate antibiotic therapy. Vaginal examination reveals a band of tissue at the vestibulovaginal junction. What is the likely diagnosis?
- Ectopic ureter
- Vestibulovaginal stenosis (vaginal stricture) (Correct answer)
- Urethral sphincter mechanism incompetence
- Transitional cell carcinoma
Correct answer: Vestibulovaginal stenosis (vaginal stricture)
Vestibulovaginal stenosis creates a pool of urine anterior to the stricture that acts as a reservoir for bacterial colonization, causing recurrent UTIs.
Question 3: A dog is diagnosed with leptospirosis after exposure to wildlife. Which organ system is MOST commonly affected, leading to the clinical presentation seen in acute leptospirosis?
- Central nervous system
- Renal and hepatic systems (Correct answer)
- Respiratory system primarily
- Musculoskeletal system
Correct answer: Renal and hepatic systems
Leptospira organisms have a particular tropism for renal tubular epithelium and hepatocytes, leading to acute kidney injury and hepatopathy as the dominant clinical syndrome.
Question 4: A 9-year-old male neutered Golden Retriever presents with progressive forelimb lameness. Radiographs of the shoulder reveal a 'moth-eaten' lytic lesion of the proximal humerus with periosteal reaction and cortical destruction. What is the most likely diagnosis and treatment?
- Osteochondrosis dissecans; arthroscopic debridement
- Osteosarcoma; limb amputation with adjuvant carboplatin chemotherapy (Correct answer)
- Septic osteomyelitis; long-term antibiotics
- Hypertrophic osteodystrophy; supportive care
Correct answer: Osteosarcoma; limb amputation with adjuvant carboplatin chemotherapy
Osteosarcoma most commonly affects the proximal humerus in large breeds; amputation combined with carboplatin or doxorubicin chemotherapy provides the best median survival.
Question 5: A 7-year-old Poodle presents with a PCV of 18%, MCV of 110 fL (macrocytosis), and a low serum cobalamin (B12). What is the most likely cause?
- Iron deficiency anemia
- Cobalamin deficiency causing megaloblastic anemia (Correct answer)
- Feline leukemia virus-like anemia
- Chronic disease anemia
Correct answer: Cobalamin deficiency causing megaloblastic anemia
Cobalamin deficiency impairs DNA synthesis in RBC precursors, causing large, immature red cells (macrocytosis) and non-regenerative megaloblastic anemia.
Question 6: During a routine physical exam, a 4-month-old Bulldog puppy is noted to have a heart murmur. Echocardiography reveals obstruction of the right ventricular outflow tract and right ventricular hypertrophy. What is the definitive therapy?
- Balloon valvuloplasty via cardiac catheterization (Correct answer)
- Open-heart surgical valvotomy
- Beta-blocker therapy alone
- Pacemaker implantation
Correct answer: Balloon valvuloplasty via cardiac catheterization
Balloon valvuloplasty is the treatment of choice for pulmonic stenosis in dogs, providing effective relief of the outflow obstruction with low morbidity.
Question 7: A 3-year-old intact male dog presents with a draining tract near the anus with recurrent abscesses. Probing reveals a communication with the rectum. What is this condition?
- Perianal fistula (anal furunculosis) (Correct answer)
- Perineal hernia
- Anal sac impaction
- Rectal prolapse
Correct answer: Perianal fistula (anal furunculosis)
Perianal fistulas (anal furunculosis) are chronic inflammatory tunneling tracts around the anus communicating with the rectum, most commonly seen in German Shepherds.
NAVLE Canine Medicine and Surgery 5
A dog presents with a rapidly growing subcutaneous mass on the trunk.
Fine needle aspirate shows granules that stain metachromatically with toluidine blue.
What is the diagnosis and recommended initial treatment?