Cataracts in Your Dog
Ron Hines DVM PhD
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As your pet gets older, you will notice a milkiness in it's eyes. These are cataracts. Cataracts are caused by a clouding of the lenses. There are medical conditions that can cause your pet to develop cataracts at an earlier age - but clouding of the lenses is a normal part of the aging process in dogs and cats.
Nuclear (lenticular) Sclerosis/Senile Cataracts
This is the most common form of cataract. It is the one you see in the photographs at the top of this page.
All our pets develop these milky cataracts. It doesn't mean they are getting senile, just that the matrix of your pet's lenses no longer reflects light as it once did. Because much light still passes through these lenses, the pets can see considerably better than owners might expect. This is only true if no other degenerative changes have occurred in the pet's eyes - changes such as glaucoma or retinal damage. Common age-related cataracts are also called lenticular sclerosis. They are quite different from the cataracts that form in older people. You will begin to notice them when your dog is about seven and when your cat is a bit older.
Senile cataracts almost always occur in both eyes simultaneously. Once they are pronounced, the pet’s eyes are often dilated (enlarged) because not enough light passes through to the retina. Instinctively dilating their eyes improves their vision in the house a bit.
Cataracts occur sooner and more frequently in some breeds of dogs. Afghans, Cockers, Chesapeake Bay Retrievers, German Shepherds, Golden retrievers, Labradors, Schnauzers, Old English Sheepdogs, Huskies Poodles, Westies and Springers are among these breeds that seem to get them first. No strains of cat are highly prone to them but they are perhaps seen more frequently in Bengals, Himalayans and Abyssinians.
As cataracts mature, they may develop crystalline cracks that look like the cracks in a marble that has been dropped or give a crushed ice appearance.
Other Causes Of Cataracts
When cataracts develop in pets at an earlier age or in just one eye, they are due to other causes.
Congenital/ Inherited Cataracts
Certain dogs are destined from birth to develop cataracts. We do not know why. Certain lines of afgahns, fox terriers, bichons, cocker spaniels, Boston terriers, miniature schnauzers, standard poodles, malamutes and westies all suffer from this condition.
Cataracts Due To Deficient Infant Diet/Malnutrition
Star-crossed puppies and kittens that did not receive an adequate diet are also prone to develop cataracts. These are often strays and foundlings whose mother subsisted on whatever scraps she could find. Deficiencies in taurine, arginine, histidine methionine and phenylalanine have all been associated with cataract formation in young animals.
Cataracts Due To Eye Injury
When a cataract forms in a single eye, it is often due to a prior eye injury. Injuries that damaged the circulatory system of fluids within the eye or the strands that hold the lenses in place can all lead to cataracts.
Cataracts Due To Eye Inflammations
Diseases that result in inflammation of the anterior chamber (uveitis) of your pet's eye can result in cataracts. In cats, feline infectious peritonitis , Feline leukemia and Feline AIDs can all result in cataract formation.
Dogs that develop diabetes sometimes develop cataracts. In these dogs, uncontrolled high blood sugar eventually causes the lenses of the eye to loose clarity.
What Should I Do For My Pet?
The first thing to do is set an appointment with your veterinarian to have your pet's eyes examined. Your veterinarian will know if the cataracts you see in your pet are typical of those seen in normal aging. If your veterinarian has any doubt, the vet may run some additional tests to eliminate the possibility of an underlying disease. If the data comes back suspicious, other diagnostic tests and treatment may be needed. If the tests are normal, most will give you the option of a referral to a veterinary ophthalmologist.
It is possible to remove cataracts that affect your pets vision. Whether or not this should be done is debatable. Dogs and cats with little or no vision appear to lead very happy lives. Both dogs and cats 'see" the world through their sense of smell as much, or more so than their sense of vision. The rich delights of tasty food, your companionship and the scents and sounds of their familiar home remain intact in these pets and they remain quite content.
A second treatment problem is that acute (accurate) vision when your pet's lenses have been removed, requires lens implants. Without them, only blurry vision is possible. There are many veterinary centers that perform lens implants in dogs and cats. The surgery can be successful. However, I do not recommend it for most pets. If you have a younger pet that has become blind or was born blind, perhaps you might consider it. The same goes for owners of work dogs that must earn their living.
If you do not go that rout, there are two factors in your pet’s favor. The first is that cataracts tend to look much worse than they really are. If a veterinarian uses his/her ophthalmoscope and can see the retina well - then the dog or cat can see out equally as well. If your pet's pupils constrict when a bright light is focused on them, also retain some vision.
Many health professionals suggest giving your pet an anti-oxidant supplement to slow the development and progression of cataracts. Vitamin E (d-alpha tocopherol acetate) and vitamin C (ascorbic acid) are easily purchased and do not taste bad to your pet. They can be dripped and crushed on its regular food. . Both these anti-oxidants seem to slow the progression of age-related changes of all kinds in animals and people.
Another thing that slows the formation of cataracts is limiting your pet's exposure to bright sun. Time your walks to the early morning and late afternoon or evening and be sure your yard has shaded area if your pet spends much time there.
Feeding a balanced diet and taking care of other pet health problems might also slow the development of all the problems associated with aging.
Blind Dogs and Cats
Pets that are blind may bump into objects. But many pets soon learn to use their remaining senses to get around this problem. Those pets only appear disoriented and hesitant in unfamiliar settings. This is because your pet's sense of smell is so much better than yours. It lives in a different World - one of aromas and scents. So it's World does not change because it has lost its sight as our World would. If an old pet's ability to do well declines, consider canine cognitive dysfunction more than the presence of cataracts.
Shining a strong light into your pet's eyes is the best way to determine if it has vision. If the aperture (diameter) of the pupil does not change, no light is reaching its retinas or there is other damage in the visual system that is causing blindness.
My chief concern in dogs with vision problems is pain or eye inflammation. Simple senile cataracts cause no pain. If your pet is squinting, lacrimating (tears) or if the shape of its eye has changed, there are probably other more serious problems occurring in its eye. Those pets need immediate veterinary attention.