NAVLE Equine Surgery and Lameness 4 — Questions and Answers
Question 1: A 2-year-old Thoroughbred colt has bilateral forelimb angular limb deformity (valgus) at the carpus identified at 4 months of age. Radiographs show the deformity originates at the distal radial physis. The foal is now presenting at 6 months without improvement. What surgical option should be considered?
- Periosteal stripping on the concave side of the deformity
- Transphyseal bridging (screw and wire or staple) on the convex side (Correct answer)
- Arthrodesis of the radiocarpal joint
- Medial condylar resection of the distal radius
Correct answer: Transphyseal bridging (screw and wire or staple) on the convex side
Transphyseal bridging on the convex (lateral) side of a carpal valgus deformity slows growth on that side, allowing the concave side to 'catch up' and correct the angular deformity.
Question 2: A horse presents with chronic forelimb lameness localized to the coffin joint. Radiographs show marked osteolysis and periarticular new bone formation. Synoviocentesis yields thick, turbid fluid with 85,000 WBC/μL (>90% neutrophils) and a glucose concentration much lower than serum. What is the next most critical step?
- Repeat radiographs in 2 weeks
- Initiate systemic corticosteroids
- Perform through-and-through joint lavage and systemic antimicrobials (Correct answer)
- Perform arthroscopic debridement under general anesthesia immediately without lavage
Correct answer: Perform through-and-through joint lavage and systemic antimicrobials
Septic arthritis requires immediate joint lavage (through-and-through or arthroscopic) combined with systemic and intra-articular antimicrobials to remove bacteria and inflammatory mediators.
Question 3: A 15-year-old Quarter Horse gelding has a chronic, non-healing wound over the lateral aspect of the pastern with a fistulous tract. Probing reveals contact with bone. Radiographs show cortical lysis of the lateral proximal phalanx. What is the definitive treatment?
- Long-term systemic penicillin without debridement
- Surgical debridement and sequestrum removal (Correct answer)
- Cast application for 8 weeks
- Intra-articular antibiotic perfusion only
Correct answer: Surgical debridement and sequestrum removal
Sequestrum formation requires surgical removal of the devitalized bone fragment combined with debridement of the surrounding infected tissue to allow healing.
Question 4: Which of the following is the most accurate description of a 'chip fracture' at the dorsal aspect of the proximal interphalangeal joint in a performance horse?
- A stress fracture of the palmar cortex of the middle phalanx
- An osteochondral fragment typically arising from the dorsal proximal rim of the middle phalanx (Correct answer)
- A traumatic fracture of the extensor process of the distal phalanx
- A subchondral cystic lesion within the proximal interphalangeal joint
Correct answer: An osteochondral fragment typically arising from the dorsal proximal rim of the middle phalanx
Dorsal chip fractures at the pastern joint are osteochondral fragments typically arising from the dorsal proximal rim of the middle phalanx, removed arthroscopically.
Question 5: A 12-year-old Hanoverian mare develops acute severe lameness 48 hours after a routine intra-articular corticosteroid injection in the stifle. The joint is severely swollen, warm, and painful. Synoviocentesis is performed. Which synovial fluid finding would most strongly indicate post-injection septic arthritis rather than a corticosteroid flare?
- WBC of 3,000/μL with 60% mononuclear cells
- WBC of 60,000/μL with 95% neutrophils and positive bacterial culture (Correct answer)
- Slightly elevated protein with no change in cell count
- Xanthochromic fluid with red blood cells
Correct answer: WBC of 60,000/μL with 95% neutrophils and positive bacterial culture
Post-injection septic arthritis is confirmed by markedly elevated WBC (>30,000/μL) with predominantly neutrophils and positive bacterial culture, distinguishing it from a transient corticosteroid flare.
Question 6: A draft horse presents with chronic bilateral hindlimb swelling below the hock and painful, progressive lameness. The skin over the palmar pastern region is thickened with exudative crusts. What condition is most likely responsible for the lameness in addition to skin disease?
- Pastern dermatitis (scratches) with secondary pastern cellulitis and possible pastern joint involvement (Correct answer)
- Thrombophlebitis of the digital veins
- Lymphangitis secondary to Corynebacterium pseudotuberculosis
- Pemphigus foliaceus
Correct answer: Pastern dermatitis (scratches) with secondary pastern cellulitis and possible pastern joint involvement
Chronic pastern dermatitis (scratches/mud fever) in draft horses can progress to cellulitis and occasionally involve the pastern joint or digital flexor tendon sheath, causing significant lameness.
Question 7: During recovery from general anesthesia following orthopedic surgery, a horse makes multiple violent attempts to stand and sustains a fracture of the contralateral limb. This type of complication is best prevented by which approach?
- Prolonging anesthesia until the horse is fully awake
- Using an assisted recovery system (head/tail ropes) with quiet, padded recovery stall (Correct answer)
- Administering acepromazine immediately post-surgery
- Placing the horse in dorsal recumbency during recovery
Correct answer: Using an assisted recovery system (head/tail ropes) with quiet, padded recovery stall
Assisted recovery using head and tail ropes in a well-padded, quiet stall helps guide the horse to a controlled, coordinated standing position, minimizing the risk of fractures and post-anesthetic myopathy.
NAVLE Equine Surgery and Lameness 4
A 2-year-old Thoroughbred colt has bilateral forelimb angular limb deformity (valgus) at the carpus identified at 4 months of age.
Radiographs show the deformity originates at the distal radial physis.
The foal is now presenting at 6 months without improvement.
What surgical option should be considered?