A cataract is any opacity in the lens of the eye. The normal lens is translucent (clear), and it transmits and focuses light onto the retina in the back of the eye. A cataract within the lens may block the transmission of light to the retina.

There are many causes of cataracts. The most common form of cataracts in the dog are genetic, inherited types. For genetic cataracts, the age of onset and severity varies among the various breeds of dogs.

Cataracts may also develop following trauma to the eye, in association with metabolic diseases such as diabetes, from nutritional disorders during puppy hood, or secondary to other eye diseases. Cataracts may develop spontaneously in old age, but should not be confused with nuclear or lenticular sclerosis, an aging change that often occurs in the canine lens and does not cause blindness. Rarely cataracts may develop following exposure to certain drugs, toxins, concentrated microwaves, radiation, or following electrocution.

Cataracts cause varying levels of vision impairment and may lead to blindness.

What to Watch For

Bluish, gray or white color change inside of the eye

Tendency to bump into things

Reluctance to use stairs or jump up onto objects

Hesitancy in unfamiliar environments

Other signs of blindness

Inflammation or redness

Pain and squinting due to the underlying cause