January is National Glaucoma Awareness Month. Although this was primarily started to promote human eye health, I think we should also include animals. Glaucoma in all species, means an increase in ocular pressure that can damage the optic nerve. In a normal eye, the fluid of the eye, aqueous humor, drains out of the eye at the same rate it is being produced keeping the pressure between 15 and 25 mm Hg for dogs and cats. (Note: The normal range will vary depending upon species and the instrument used to measure the pressure.) In glaucoma, the drainage is blocked causing the pressure to sky rocket. It this condition isn’t treated immediately, blindness often results.
The most common sign of glaucoma in dogs and cats is a raised third eyelid. Dogs and cats have an extra eyelid that originates from the side of the eye nearest the nose and spreads outward. Other signs include redness, swelling and unequal pupil size (anisocoria). Glaucoma is very painful! Animals will often squint, rub their faces on furniture or paw at the effected eye. I have seen a few tear profusely as well.
I see glaucoma most commonly in cocker spaniels and Labrador retrievers in Arizona. When I practiced in Minnesota, I saw it in Chow chows, Basset hounds and Siberian huskies as well as cockers and labs. With so many breeds being crossed to create designer breeds, I expect to see more cases as this disease appears to have a genetic component.
Glaucoma can also be caused by other medical problems. Uveitis which means inflammation of the uveal tract of the eye is a common cause of glaucoma. In Arizona, tick fever and valley fever are common causes of uveitis. Other causes of glaucoma include cataracts, trauma and cancer.
If you notice these signs in your pet, please seek medical assistance immediately. Waiting, even a few hours, may mean the difference between sight and blindness. I know of a dog who lost vision in his eye after only 60 minutes of increased pressure.
-Balas, M. ‘Keep your sights on animal eye health’. Pet Talk. OREGONLIVE, Jan. 15, 2014.