08/31/2026
π¨ INTERESTING CASE ALERTπ¨
We recently saw a patient for unusual behavior: holding her head abnormally high while eating and drinking. A dental had been performed the day prior with no abnormalities identified.
On presentation, she had mild ptosis (drooping) of the right eye. During the beginning of our examination, while mildly palpating the TMJ, our patient suddenly flipped over and experienced loss of coordination and horizontal nystagmus for approximately 5 minutes.
Radiographs revealed suspected chronic changes at the temporohyoid joint, and a guttural pouch endoscopy revealed an enlarged stylohyoid bone on the affected side.
Medical management was initiated, but unfortunately, there was no improvement. Her facial paralysis progressed, with a notable ear droop, eyelid droop, lip pulled toward the unaffected side, and a slight head tilt.
At this point, referral for a CT scan with Dr. Weston Davis was recommended. Just prior to CT, she developed a secondary corneal ulcer due to decreased eyelid function.
CT confirmed Temporohyoid Osteoarthropathy (THO), and surgery (ceratohyoidectomy) was performed by Dr. Davis. Our patient is currently doing well- making progress with neurological signs, and the corneal ulcer is healing well thanks to Dr. Carastro's team!
π§ What is THO?
Temporohyoid Osteoarthropathy (THO) is a condition affecting the temporohyoid joint and stylohyoid bone in horses. Because of the location of these structures, even subtle changes can have significant neurologic consequences.
Horses with THO may show signs including:
β’ Facial nerve paralysis β drooping of the ear, eyelid, or lip
β’ Head shaking or sensitivity around the poll/ear
β’ Abnormal eye movements (nystagmus)
β’ Loss of balance or other vestibular signs
β’ Head tilt
β’ Changes in drinking or difficulty chewing
Early recognition is important. Inflammation, abnormal bone changes, or fusion of the temporohyoid joint can affect surrounding structures and cranial nerves.
This case is a great reminder that neurologic signs don't always present in obvious ways. An unusual change in behavior may be the first clue that something more significant is going on.
