Cataracts

A cataract is any opacity within a lens. The opacity can be very small (incipient cataract) and not interfere with vision. It can involve more of the lens (immature cataract) and cause blurred vision. Eventually, the entire lens can become cloudy, and all functional vision lost. This is called a mature cataract.

What are the signs of cataracts?

A dog with cataracts will usually show some cloudiness to the eye, if you see a photo of the dog, the eyes will not reflect a fluorescent green circle over the eye in the photo as the opaqueness to the lens prevents the camera flash light being fully reflected back from the tapetum (the reflective structure that lies beneath the retina).

Cataracts or Nuclear Sclerosis?

Senior dogs (usually beginning around 5 - 6 years of age) develop a hardening of the lens (Nuclear Sclerosis) that causes the lens to have a greyish appearance. The greyish-blue haze increases as the dog ages. Nuclear sclerosis is NOT a cataract, and does not usually interfere with vision and treatment is usually not necessary.

When a dog owner suspects that their older dog might have cataracts, the vast majority of the time the dog does not have cataracts, but has the much more common condition known as nuclear sclerosis. Nuclear sclerosis is a normal change that occurs in the lenses of older dogs. Nuclear sclerosis appears as a slight greying of the lens. It usually occurs in both eyes at the same time. 

Causes of cataracts

• Many cataracts in dogs are inherited & can occur at any age. The cataract may develop rapidly over weeks, or slowly over years, and occur in one or both eyes. Different breeds of dogs (including mixed-breeds) have different characteristics of cataract development.
• Senile cataracts occur in dogs over six years of age and are a later-life problem caused from increasing years.
• The second-most common cause of cataracts in dogs is diabetes (diabetes mellitus). Two-thirds of diabetic dogs will develop blinding cataracts within the first year of being diabetic and it is normally the case that the cataracts form very shortly after the dog becomes diabetic.
• Cataract can also occur in dogs in which the lens capsule is ruptured due to trauma. The trauma can be penetrating (such as a cat claw injury etc.) or a severe blow to the eye that results in lens capsular rupture.
• Cataracts can also develop due to nutritional deficiencies in dogs, such as orphan puppies on a milk-replacer diet where there are inadequate levels of Vitamin E and other antioxidant vitamins/essential fatty-acids. These are called nutritional cataracts, and they often improve as the puppy matures.

How are Cataracts treated?

Once a lens has developed a cataract, there is no known method to make the lens clear again. Immature, mature, and hyper-mature cataracts can be treated by surgically removing them and replacing the lens with an intraocular lens (made from plastic), nutritionally caused cataracts often benefit from nutritional supplements and do not necessarily require cataract replacement surgery.