Cataracts and cloudy eyes

Most older dogs develop a bluish haze in the centre of the lens. This is nuclear sclerosis, a normal hardening of the ageing lens that has little effect on vision. A cataract is different: an opacity of the lens or its capsule that blocks light and can blind. The two are told apart on examination, and surgery to remove the lens is the only definitive cataract treatment¹. Among nearly 40,000 dogs seen for cataracts at North American teaching hospitals, the highest breed rates were in the Smooth Fox Terrier, Havanese, Bichon Frise, Boston Terrier, Miniature Poodle, Silky Terrier and Toy Poodle².

Cataracts in seniors are also a common complication of diabetes, so a dog whose eyes cloud quickly should have its blood sugar checked³.

Signs of failing vision are bumping into things in dim light, hesitating at stairs, and not tracking a thrown treat. Keep furniture where it is, use a night light, and let the dog's nose and routine do the work; most dogs adapt to slow vision loss well. A red, painful or suddenly cloudy eye is a same-day call.

This is general information, not a diagnosis. Your vet knows your dog.

Sources

1. The Lens in Animals. Merck Veterinary Manual. Accessed 2026-09-22.
2. Prevalence of primary breed-related cataracts in the dog in North America (Gelatt KN, MacKay EO). Veterinary Ophthalmology 8(2):101-111, 2005 (peer reviewed). Accessed 2026-09-22.
3. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats (Behrend E et al.). American Animal Hospital Association, Journal of the American Animal Hospital Association 54(1):1-21. Accessed 2026-09-22.