Histologic Evaluation of Palmar Digital Nerves after Perineural Injection of 2% Ammonium Chloride in Miniature Horses.

This research examines the impact of a 2% ammonium chloride solution on the palmar digital nerves in miniature horses, commonly targeted to manage lameness. The study found minimal to severe nerve degeneration following the injection but concluded that the substance does not interfere with future surgical nerve removal and is as safe as a saline solution.

Background of the Research

• The research focuses on the use of neurolytic compounds, such as 2% ammonium chloride (2% AC), in the management of lameness in horses.
• Lameness in horses is often related to the foot and affecting the palmar digital nerves can ease this condition.
• Previous research has not sufficiently evaluated the safety and effectiveness of 2% AC, which is largely used in vet practices.

Design and Methodology of the Study

• This study involved six miniature horses to which 2% AC was injected into the palmar digital nerves, while a 0.9% saline solution was served as the control.
• 3 horses received the 2% AC and one received the saline solution.
• Nerve samples were then taken from each horse at intervals (5, 12, 19, 35, 47, 62 days) post-treatment.
• A procedure called neurectomy, performed under general anesthesia, was used to collect the nerve samples.
• The inflammation induced by perineural injection was measured by the change in pastern superficial skin temperature 24-hours after the injections.

Findings of the Study

• A temperature increase of 2.43 ± 0.79°C and 1.69 ± 0.55°C was recorded in the 2% AC and control groups respectively, suggesting a comparable level of inflammation.
• The histological evaluation showed varying degrees of Wallerian degeneration (nerve degeneration) after perineural injection of 2% AC ranging from absent to severe…
• The saline solution also showed similar signs of nerve degeneration.

Interpretation and Conclusion of the Research

• The main conclusion is that 2% AC is as safe as the 0.9% saline solution.
• Even though mild to severe Wallerian degeneration was found up to 62 days after injection, it was determined that there was no interference with subsequent neurectomy.
• This finding substantiates the usage of 2% AC by equine practitioners as it is not detrimental to subsequent surgical interventions and is as safe as a saline solution.