ASK THE VET

Dogs cope well with loss of vision

12/30/2012

Dear Dr. Thompson: My sister was just informed that her dog was going blind in one eye and likely will lose the vision in the other eye. Does she have any options to prevent this from getting worse or what will happen if she does go blind?

Loss of vision can result from changes in many parts of the eye and the treatment options depend on what is affected. Unfortunately I can only speak in broad terms since I have not evaluated your sister’s dog.

An inherited condition called progressive retinal atrophy (PRA) where there is degeneration of the retina affects many breeds of dogs, especially Labrador retrievers. Over time the retina loses sensitivity to light and eventually blindness results. The first sign most people notice is progressive night blindness and dilated pupils. However, this affects both eyes equally and is probably not affecting your sister’s dog.

Cataracts are cloudy spots in the clear lens of the eye that can affect vision. A number of processes can lead to cataracts and the progression is quite variable. Diabetes is a major cause of cataract development in dogs and I would expect your sister’s dog has would have other symptoms. Cataracts can lead to inflammation in the eye over time that could result in an increase in pressure in the eye called glaucoma. Cataract surgery is available for pets from a veterinary ophthalmologist, but when secondary glaucoma develops, surgery might not be an option.

Vision can also deteriorate if the clear front covering of the eye called the cornea has chronic inflammatory changes. This condition, called pannus, can develop from a number of processes, but the most common sign is a thick black film over the eye. Chronic dry eye is the most common cause and is treatable. Her veterinarian can measure the body’s ability to produce tears and if it is low, a topical medication called cyclosporine can increase the tear quantity. The chronic inflammation can be reversed with long-term treatment with topical steroid drops. Over time the black film will thin and recede and vision can improve.

If any of the causes of blindness are not treatable, then she may eventually lose vision. However, vision loss in dogs does not dramatically impact their ability to get around and lead a normal life. Dogs have the capacity to “smell” their way through the environment and function quite well. Complete blindness in dogs many times goes unnoticed by outsiders.

Hopefully, your sister’s dog has options to treat the loss of vision you describe. Referral to a veterinary ophthalmologist might help her understand her dog’s condition better.

Questions for Dr. Gary Thompson can be emailed to askthevet@theblade.com or mailed to The Blade, Attn. Ask the Vet, 541 N. Superior St., Toledo, OH 43660. Dr. Thompson regrets the he cannot answer individual letters.