Stringhalt in horses: a distal axonopathy.

The research article investigates the neuropathology of a horse affected with stringhalt, a disorder that affects the neuropathy in horses. It concludes that the disease should be classified as a distal axonopathy, a condition characterized by the degeneration of nerve axons.

Investigation Details and Methodology

• The study employed a comprehensive examination of a horse suffering from stringhalt, a condition that affects the movement in horses, causing a sudden jerk or hop of the hind limbs.
• The researchers used qualitative and quantitative light and electron microscopy to analyze the affected nerves. They also performed single teased fibre preparations of peripheral nerve to identify the type and extent of nerve damage.

Findings: Axonal Degeneration and Severity

• The research found that the horse exhibited predominantly axonal degeneration. The stage of the degeneration was in accordance with the duration or period of the clinical symptoms observed in the horse.
• A notable feature of the condition was the selective involvement of large myelinated nerve fibres. Myelinated nerve fibres are nerve cells wrapped in myelin, a substance that speeds up the transmission of nerve signals.
• The severity of the pathological changes in the peripheral nerves tended to increase from proximal to distal areas.

Most Affected Areas and Neurogenic Atrophy of Muscles

• The study identified the long left recurrent laryngeal nerve as the most severely affected, followed by the right longer left recurrent laryngeal nerve, and then the hindlimb and forelimb nerves.
• Neurogenic atrophy or the weakening and loss of muscle mass resulting from nerve damage was observed in muscles that were innervated by the affected peripheral nerves. The severity of atrophy also showed a distally graded increase.

Central Nervous System Unaffected

• Interestingly, no lesions or abnormalities were observed in the horse’s central nervous system, indicating that stringhalt only affects the peripheral nerves.

Conclusion and Classification of the Disease

• Based on these findings, the researchers concluded that stringhalt should be classified as a distal axonopathy. This term refers to a disease that primarily causes degeneration of the distal (furthest from the center of the body) portions of nerve axons.