26.5.4: Navicular degeneration Flashcards
What pathological changes do we see with navicular degeneration?
- Focal loss of the medullary architecture with medillary sclerosis
- Fibrocartilagenous change of the flexor surface
- Traumatic fibrillation of the deep digital flexor tedon which may lead to adhesion formation between the tendon and bone
- Enthesiophyte formation of the proximal and distal borders of the bone
Signalment for navicular degeneration
- Genetic component: seen more in warmbloods, TBs, quarterhorses
- Seen less in Arabs, Friesians
- Not seen in donkeys or ponies
- Typically older horses >10 yrs
- Conformation is very important
Clinical signs of navicular degeneration
- Insidious onset bilateral forelimb lameness, initially intermittent, leading to changes in performance
- Sound in straight line but lame on lunge
- Rarely positive on hoof testers
Diagnosis of navicular degeneration
- Positive response to PDNB (typically this gives complete resolution ± lameness shifts to the other leg)
- Anaesthesia of the navicular bursa is more specific but more complex, requires radigraphic guidance and contrast so not done in primary practice
Which view of the navicular bone is shown here?
Lateromedial
Which view of the navicular bone is shown here?
Palmaroproximal palmarodistal 45 degree oblique (flexor navicular view)
Which view of the navicular bone is shown here?
Dorsoproximal palmarodistal 85 degree oblique (upright navicular)
Pros and cons of MRI for diagnosing navicular pathology
✅ Can diagnose multiple pathologies
✅ Early diagnosis of bone pathology
❌ Cost - v expensive
Conservative management options for navicular degeneration
- Analgesia e.g. phenylbutazone PO
- Corrective farriery: wedges, rolled toe, bar shoes
- Corticosteroids: trimcinolone, methylprednisolone
- Biphosphates (tiludronate, clodronate)
- (Vasodilators e.g. isozuprine)
Surgical treatment options for navicular degeneration
Palmar digital neurectomy
* Provides pain relief
* Nerve sensation will eventually restore
* Complications include neuroma, catastrophic DDFT breakdown, pedal osteitis / food penetration
Other surgical procedures are unproven.
What are the key points in management of navicular degeneration?
- Management only; no cure
- Most horses eventually reach non-response to treatment
- NSAIDs, farriery, ± corticosteroids can prolong soundness
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