What it is
The lens sits just behind the pupil and focuses light onto the retina, much like the lens of a camera. It is made of tightly packed proteins arranged so precisely that it stays crystal clear. In a cataract these proteins clump together and the lens turns cloudy, first in a small spot and sometimes, over time, across the whole lens.
A cataract can be inherited and show up in a young dog, develop as a dog ages, or follow another illness such as diabetes, an eye injury or long-standing inflammation inside the eye. The faint bluish haze of an ageing lens is a different change that barely affects sight, and only an eye examination tells the two apart.
Dogs lean heavily on their noses and ears, so a dog may adapt to failing sight better than you expect. Keeping the furniture where it is, speaking before you touch and blocking off stairs all help a dog that sees less to move with confidence.
Signs you may notice
- Cloudy or white pupil
- Bumps into furniture
- Hesitant in dim light
- Misses a thrown toy
- Unsure on stairs
You may notice a greyish or white tint in the pupil, and the dog starts moving hesitantly in unfamiliar places, bumping into things or missing a thrown toy. The lens can also turn slightly bluish with age, but whether it is a cataract is for a vet to determine.
When to see a vet
Book a visit as soon as you notice cloudiness in an eye or a change in how your dog finds its way around. A red, painful or squinting eye should be seen without delay.
This is general information, not veterinary advice. For your own dog's health, tests and treatment, see a vet.