NAVLE Equine Surgery and Lameness 3 — Questions and Answers
Question 1: A 6-year-old Standardbred pacer develops progressive bilateral hindlimb ataxia and weakness that worsens going downhill. Cervical radiographs show vertebral canal stenosis at C4-C5. What is the most likely diagnosis?
- Equine protozoal myeloencephalitis (EPM)
- Cervical vertebral stenotic myelopathy (Wobbler syndrome) (Correct answer)
- Equine herpesvirus myeloencephalopathy
- Stringhalt
Correct answer: Cervical vertebral stenotic myelopathy (Wobbler syndrome)
Cervical vertebral stenotic myelopathy (Wobbler syndrome) presents with progressive spinal cord compression causing symmetric ataxia and weakness, confirmed by vertebral canal stenosis on radiographs.
Question 2: An 8-year-old Arabian mare undergoes ovariectomy via flank laparotomy. On post-op day 2, she develops acute abdominal pain and pyrexia. Abdominocentesis reveals yellow-tinged fluid with a total protein of 4.5 g/dL and WBC of 90,000 cells/μL. What is the most likely complication?
- Incisional seroma
- Peritonitis secondary to intestinal contamination or pedicle infection (Correct answer)
- Cecal impaction
- Normal post-operative peritoneal response
Correct answer: Peritonitis secondary to intestinal contamination or pedicle infection
Markedly elevated peritoneal fluid protein and WBC with fever and pain indicate septic peritonitis, a serious complication of flank ovariectomy typically due to contamination or pedicle infection.
Question 3: Radiographs of a 4-year-old Warmblood show osteochondral fragments at the dorsal aspect of the proximal interphalangeal (pastern) joint. The horse has mild lameness improved by intra-articular analgesia. What is the recommended treatment?
- Systemic NSAIDs and box rest for 6 months
- Arthroscopic removal of osteochondral fragments (Correct answer)
- Intra-articular sodium hyaluronate injections only
- Pastern joint arthrodesis
Correct answer: Arthroscopic removal of osteochondral fragments
Osteochondral fragments at the pastern joint are best treated by arthroscopic removal, which provides the most reliable return to athletic function.
Question 4: A horse presents with sudden onset severe hindlimb lameness and a palpable defect in the middle gluteal muscle. The horse had been exercising at speed just before onset. What is the most likely diagnosis?
- Sacroiliac subluxation
- Fibrotic myopathy of the semimembranosus
- Exertional rhabdomyolysis with muscle tear (tying-up) (Correct answer)
- Femoral nerve paralysis
Correct answer: Exertional rhabdomyolysis with muscle tear (tying-up)
Acute muscle tear of the gluteal region with a palpable defect following high-intensity exercise is consistent with exertional rhabdomyolysis severe enough to cause myofibrillar disruption.
Question 5: During exploratory laparotomy for colic, the surgeon identifies a section of small intestine that is dark purple-black in color with no palpable pulse in the mesenteric vasculature after 10 minutes of warm saline lavage. What is the appropriate surgical decision?
- Replace the intestine and close; reassess in 24 hours
- Perform resection and anastomosis of the non-viable segment (Correct answer)
- Apply topical papaverine to improve perfusion
- Pack the abdomen and stage the surgery
Correct answer: Perform resection and anastomosis of the non-viable segment
Non-viable intestine (no color change, no mesenteric pulse after warming) must be resected with end-to-end or side-to-side anastomosis to prevent endotoxemia and peritonitis.
Question 6: Which of the following best describes the 'stacked' or 'wedge' effect seen radiographically in horses with palmar foot syndrome (navicular syndrome)?
- Increased thickness of the digital flexor tendon on lateromedial view
- Synovial invaginations (synovial fossae) that appear as lucent 'lollipop' shapes in the navicular bone (Correct answer)
- Gas lucency around the navicular bursa
- Periosteal proliferation at the palmar cortex of the navicular bone
Correct answer: Synovial invaginations (synovial fossae) that appear as lucent 'lollipop' shapes in the navicular bone
Synovial fossae (invaginations) in the navicular bone appear as round to oval radiolucencies on the flexor surface, often called 'lollipop' lesions, and are associated with navicular disease.
Question 7: A 5-year-old Thoroughbred racehorse has a complete transverse fracture of the proximal sesamoid bone following a race. Which statement best describes the prognosis for return to racing?
- Excellent prognosis with internal fixation using lag screws
- Guarded to poor prognosis; most horses are retired from racing after this injury (Correct answer)
- Good prognosis with 6 weeks of stall rest alone
- Prognosis depends solely on which sesamoid (medial vs. lateral) is fractured
Correct answer: Guarded to poor prognosis; most horses are retired from racing after this injury
Complete transverse fractures of the proximal sesamoid bone carry a guarded to poor prognosis for return to racing due to disruption of the suspensory apparatus and risk of fetlock hyperextension.
NAVLE Equine Surgery and Lameness 3
A 6-year-old Standardbred pacer develops progressive bilateral hindlimb ataxia and weakness that worsens going downhill.
Cervical radiographs show vertebral canal stenosis at C4-C5.
What is the most likely diagnosis?