ICVA Equine Lameness and Neurology 3 — Questions and Answers
Question 1: What is the primary action of the deep digital flexor tendon (DDFT) in the equine foot?
- Extension of the coffin joint
- Flexion of the coffin joint and support of the navicular bone (Correct answer)
- Rotation of the pedal bone
- Stabilization of the proximal interphalangeal joint only
Correct answer: Flexion of the coffin joint and support of the navicular bone
The DDFT flexes the coffin joint and wraps around the navicular bone, placing it under significant tension during weight-bearing.
Question 2: Fibrotic myopathy in horses most commonly affects which muscle group?
- Biceps brachii
- Semitendinosus and semimembranosus (Correct answer)
- Gluteal muscles
- Triceps brachii
Correct answer: Semitendinosus and semimembranosus
Fibrotic myopathy most commonly affects the semitendinosus and semimembranosus muscles, resulting in a characteristic gait abnormality.
Question 3: Which diagnostic finding is most consistent with a diagnosis of botulism in horses?
- Elevated CSF protein with pleocytosis
- Progressive flaccid paralysis with preserved consciousness (Correct answer)
- Spastic tetraparesis with hyperreflexia
- Focal asymmetric ataxia
Correct answer: Progressive flaccid paralysis with preserved consciousness
Botulism causes flaccid paralysis by blocking acetylcholine release at neuromuscular junctions, while mental status remains normal.
Question 4: During a lameness examination, a positive response to flexion of the distal limb (distal limb flexion test) indicates disease in which region?
- Stifle and hip
- Fetlock, pastern, or foot (Correct answer)
- Carpus and radius
- Shoulder joint
Correct answer: Fetlock, pastern, or foot
Distal limb flexion stresses the fetlock, pastern, and foot joints, so exacerbation of lameness suggests pathology in those areas.
Question 5: Which radiographic view is most useful for evaluating the palmar aspect of the navicular bone for lysis or cyst formation?
- Lateromedial view
- Dorsoproximal-palmarodistal oblique (skyline) view (Correct answer)
- Dorsopalmar view
- Oblique 45° view
Correct answer: Dorsoproximal-palmarodistal oblique (skyline) view
The dorsoproximal-palmarodistal oblique (skyline) view provides an en face projection of the navicular bone's flexor surface.
Question 6: A horse presenting with acute-onset unilateral hindlimb knuckling and toe dragging without pain is most consistent with:
- Severe laminitis
- Femoral nerve injury
- Peroneal nerve paralysis (Correct answer)
- Tarsal sheath effusion
Correct answer: Peroneal nerve paralysis
Peroneal (fibular) nerve paralysis causes inability to flex the hock and extend the digit, resulting in knuckling and toe dragging.
Question 7: In equine nuclear scintigraphy, a 'hot spot' in the foot region is most likely indicative of:
- Decreased blood flow to the area
- Increased osteoblastic activity or inflammation (Correct answer)
- Nerve demyelination
- Synovial fluid accumulation
Correct answer: Increased osteoblastic activity or inflammation
Increased radiopharmaceutical uptake ('hot spot') reflects increased osteoblastic activity, bone remodeling, or local hyperemia.
ICVA Equine Lameness and Neurology 3
What is the primary action of the deep digital flexor tendon (DDFT) in the equine foot?