Horner’s syndrome in the horse: experimental induction and a case report.

This research article discusses an experiment and a case study involving Horner’s Syndrome, a neurological disorder, in horses. The symptoms of the disorder were induced in six horses, and also observed in a case where a horse naturally developed the syndrome due to a tumor.

Experimental Induction of Horner’s Syndrome

• The study induced Horner’s Syndrome (HS) in six horses by surgically intervening in the middle third of the neck. Specifically, a procedure called “unilateral surgical section of the cervical sympathetic trunk” was performed. This essentially means cutting nerves in the neck, affecting the horse’s ability to control certain responses like pupil dilation and sweat production.
• The degree of these symptoms, including ptosis (drooping eyelids), miosis (constricted pupils), enophthalmos (sunken eyes), hemilateral sweating (sweating on one side of the body), and a temperature increase in the face and neck on the affected side, varied both between different horses and within the same animal. Some symptoms, such as miosis, enophthalmos, and temperature difference, were difficult to detect.

Naturally Occurring Horner’s Syndrome

• In addition to the experimental cases, the research also included a naturally occurring case where a 17-year-old gelding developed HS as a result of a mediastinal tumour. Mediastinal tumors can affect the nervous system and lead to a variety of symptoms, including those associated with HS. This case provided additional understanding about how HS manifests in a non-experimental setting.

Clinical Importance of Recognizing Horner’s Syndrome

• The research emphasizes the importance of recognizing HS in a clinical setting. Detecting the condition may assist veterinarians in identifying where lesions are located.
• In particular, the study suggests that if HS is accompanied by nasal haemorrhage (nosebleeds), this can be a strong indicator of a condition called “guttural pouch mycosis“. This is a serious fungal infection that occurs in the guttural pouches, air-filled sacs located in a horse’s head.