Glaucoma in Foals

Q. I am looking for information on glaucoma in foals. Any information will be helpful.


A. Glaucoma is a disease characterized by an increase in pressure within the eye that is higher than the eye can tolerate. Glaucoma causes blindness from damage to the optic nerve and retina (the structures that collect light and transmit visual signals to the brain).

Three types of glaucoma occur in horses: 1) Primary glaucoma occurs when pressure in the eye increases, but there is not an obvious ocular (eye-related) cause; 2) Secondary glaucoma occurs because of the presence of other diseases in the eye, such as inflammation or cancer; and 3) Neonatal glaucoma occurs soon after birth in a foal.

Glaucoma in foals is usually neonatal or secondary glaucoma. Both types are relatively rare. Secondary glaucoma develops after a severe sickness (systemic infection) in foals, such as pneumonia. Bacteria from the blood enters the eye, causes inflammation, and the foal develops glaucoma. This can occur in any age foal. In neonatal glaucoma, the foal is usually born with an enlarged, cloudy eye with linear white streaks in the cornea and a widely dilated pupil. Vision is usually decreased. The cause of this condition is unknown. It can occur in any breed, and it is not thought to be inherited.

With either cause of glaucoma, prognosis for vision is poor. However, the earlier the diagnosis and treatment, the better the foal's chances. Diagnosis is made by measuring the pressure with an instrument called a tonometer. Glaucoma is commonly treated with topical eye drops (Timolol 0.5% twice a day) and/or laser therapy.

About the Author

Brian C. Gilger, DVM, MS, Dipl. ACVO

Brian C. Gilger, DVM, MS, Dipl. ACVO is an Associate Professor of Ophthalmology at North Carolina State University.

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