Cataracts are a clouding of the lens of the eye. The condition can be so minor it doesn't even interfere with vision, and it can be serious enough to cause permanent blindness in your dog, or less often, your cat.
Canine cataracts are much more common and clinically significant than feline cataracts. Most cataracts in dogs are an inherited condition, however, diabetes is also a common and preventable cause. Other causes for cataracts in dogs are systemic drug toxicity, other underlying eye conditions, trauma to the eye, and the aging process.