Horner's syndrome in large animals

Area of Science:

• Veterinary Neurology
• Autonomic Nervous System Physiology
• Comparative Animal Anatomy

Background:

• The sympathetic nervous system regulates various autonomic functions in the head, including sweating and vascular tone.
• Understanding the clinical manifestations of sympathetic denervation is crucial for diagnosing neurological conditions in large animals.

Purpose of the Study:

• To investigate and compare the clinical signs of surgically induced Horner's syndrome following sympathetic denervation of the head in horses, cows, sheep, and goats.
• To document species-specific variations in the presentation of Horner's syndrome in these domestic animals.

Main Methods:

• Surgical transection of sympathetic nervous innervation to the head was performed in horses, cows, sheep, and goats.
• Lesion sites included preganglionic transection in all species and ganglionic-postganglionic transection in two additional horses.
• Clinical signs of iatrogenic Horner's syndrome were observed and documented for each species.

Main Results:

• Ptosis (eyelid drooping) was the most consistent sign across all four species.
• Horses exhibited prominent unilateral facial and proximal neck sweating, particularly at the ear base.
• Cows showed pinna vasodilation and warmth, with reduced nasal sweating; goats and sheep primarily displayed mild ptosis.

Conclusions:

• Horner's syndrome presentation varies significantly among horses, cows, sheep, and goats after head sympathetic denervation.
• Subtle ophthalmologic signs of Horner's syndrome in these large animals can be easily missed during routine clinical examination.
• Species-specific responses highlight the complex autonomic innervation patterns in the heads of large domestic animals.