Cataracts in dogs most typically affect senior canines, but puppy cataracts can be present at birth. A cataract is an opacity of the lens inside the puppy's eye. The lens is located directly behind the pupil and normally is transparent.
Dogs suffer from cataracts more commonly than any other species. Although most cases are found in dogs over the age of five, cataracts can develop at any age. Some dogs are born with them or develop them as puppies.
How Cataracts Are Classified
A cataract interferes with normal vision. It's often classified by the age of the dog when it develops. Congenital cataracts are present at birth, juvenile cataracts develop during puppyhood, and senile cataracts occur on senior dogs.
The degree of the cloudiness of the lens also impacts the classification of the cataract. The opacity can vary from a little spot of white to a totally opaque structure that affects the entire lens. If the lens becomes completely masked, the result is blindness. Depending on the degree of opacity, you may notice cloudiness within the pupil space that looks like a white marble inside the eye.
Why Cataracts Develop
Several things can result in lens changes. Injury, as well as the resulting inflammation, may cause a cataract. When that happens, it usually affects only one eye. Some puppies are born with cataracts. Cataracts resulting from poor nutrition are possible, but rare because of modern advances in canine diets. In some cases, the cataract is idiopathic, which means the cause cannot be identified.
Dogs most often suffer from senile, or "old age," cataracts; almost all dogs older than eight years suffer some degree of cloudiness to the lens of the eye. Cataracts in dogs also may result from diabetes mellitus when the lens protein is injured by metabolic changes.
But most canine cataracts are inherited, especially in certain breeds. Poodles, Cocker Spaniels, Boston Terriers, Karelian Bear Dogs, Wirehaired Fox Terriers, Siberian Huskies, Golden Retrievers, Old English Sheepdogs, and Labrador Retrievers are reported to be affected most often.
How Are Cataracts Treated
A cataract may affect only a portion of the lens and consequently some dogs show few signs at all. Cataracts that covers the entire lens may still allow some vision, so the pup can “see” around the cloudy portion. Dogs are experts at making accommodations and relying more on smell sense and hearing to compensate for vision problems.
Treatment may not be necessary until a high degree of vision is lost and cataracts become problematic for the pup. Often, even blind dogs continue to do well in familiar surroundings by relying on their other acute senses. When an underlying cause can be identified, it’s treated when possible. For example, correcting the nutrition or treating the inflammation that resulted from an injury to the eye.
Puppies and Congenital Cataracts
Puppies born with congenital cataracts can improve as they mature. That’s because the lens inside the puppy’s eye grows along with the dog. When the area of cloudiness on the lens remains the same size, by the time the puppy becomes an adult, the affected portion of the lens is relatively small. By adulthood, many dogs born with cataracts are able to compensate and see "around" the cloudiness.
Cataract Surgery for Dogs
In dogs that have trouble navigating due to vision loss, sight can be restored to near normal by surgery. This procedure is not indicated when the cataract is caused by inflammation, however.
The same surgical techniques used on people for cataracts are applied to pets. Most veterinary ophthalmologists in private practice or at a university can do the surgery, which is done under general anesthetic.
The lens itself is contained in a kind of capsule, like an eggshell. Most commonly, surgery removes the front part of the shell and the contents inside, while leaving the back half of the capsule/shell intact. In some cases, the whole lens is removed and a new lens is transplanted to replace the damaged lens. Dogs that have the surgery generally do quite well.