Unilateral ataxia and head tilt in a 7-year-old Thoroughbred stallion. Temporohyoid osteoarthropathy.

The research article discusses the case of a 7-year-old Thoroughbred stallion presenting symptoms such as ataxia, a leftward head tilt and a cloudy left eye, revealing a diagnosis of temporohyoid osteoarthropathy.

Case Overview

• The study focuses on a 7-year-old Thoroughbred stallion that showed symptoms of ataxia, a continuous head tilt to the left, and opacity in the left eye. It also had a prior history of ocular surgery but the details are unknown.
• The horse had recently been transported to Australia from another country and is primarily used for breeding.
• The stallion had a moderate body condition and exhibited alertness and responsiveness during the examination.
• The stallion’s left cornea showed signs of leukoma and melanosis in the central and inferior areas, which are consistent with a previous conjunctival pedicle graft.

Additional Symptoms

• Further examination showed additional symptoms only on the stallion’s left side: rightward muzzle deviation, muscle slackness in the muzzle and lower lip, a fixed position of the ear, ptosis, head tilt, body lean, and hemi-ataxia.
• The horse also had food lodged in the oral cavity, lacked an active eyelid reflex, and its head tilt and body lean were more pronounced in dim light.
• There was no muscle weakness in the stallion’s limbs. Radiography and endoscopy of the skull and guttural pouches revealed no other abnormalities.

Progression of the Disease

• The horse initially experienced difficulty eating on its left side but could still consume the food provided. However, a few days later, it showed advanced neurological issues such as loss of muscle tone in the eyelid, lower lip and nostril, and a lack of tear production on the right side.
• The stallion also developed breathing difficulties, an audible inhalation, and both nostrils collapsed. Its ability to eat and drink severely deteriorated, and all four limbs showed signs of ataxia.
• The right eye also manifested a dull cornea and a superficial ulcer in the central area. Based on these observations, the horse was diagnosed with temporohyoid osteoarthropathy, a degenerative condition that affects the head and neck.