Stringhalt in horses: a distal axonopathy.

Area of Science:

• Neuropathology
• Equine neurology
• Peripheral nerve disorders

Background:

• Stringhalt is a poorly understood equine neurological disorder characterized by hyperflexion of the hind limbs.
• Previous research has not definitively identified the underlying neuropathological cause of stringhalt.

Observation:

• A detailed neuropathological examination of a horse with stringhalt was conducted using light and electron microscopy, and teased nerve fiber preparations.
• The study focused on peripheral nerves and associated muscles, with no central nervous system lesions observed.

Findings:

• The primary finding was axonal degeneration, predominantly affecting large myelinated nerve fibers in the peripheral nervous system.
• Pathological changes showed a proximal-to-distal gradient of increasing severity, with the recurrent laryngeal nerves and hindlimb nerves being most affected.
• Neurogenic muscle atrophy correlated with the severity of peripheral nerve damage, also exhibiting a distal progression.

Implications:

• The results support classifying equine stringhalt as a distal axonopathy.
• Understanding the specific pattern of nerve degeneration can inform future diagnostic and therapeutic strategies for stringhalt.
• This research contributes to the broader understanding of peripheral neuropathies in large animals.