One of the most common problems affecting the eyes of dogs is canine cataract. While canine cataract presents at different ages, and in various forms, in general they can affect all dog breeds.

Recent research carried out by veterinary scientists has shown that certain types of canine cataracts are more common in specific breeds. Dog cataracts are very widespread, and unfortunately there is still a lot that we do not know about this condition.

This article covers some of the different forms of dog cataracts and gives details of the likely age of onset.

The word "cataract" actually means 'to break down.' The breakdown referred to is the disruption of the natural arrangement of the lens fibers within the eye itself. This disruption results in a form of oxidation and a loss of transparency to the lens. To the pet’s owner a dog’s cataract often appears to have a milky white appearance. There is however a condition known as nuclear sclerosis which has a similar appearance to that of cataract. In many situations the milky eye of the dog is not due to canine cataracts, but to a condition that is known as 'nuclear sclerosis.' Nuclear sclerosis is a change that takes place in the lens of older dogs. It manifests itself physically as a graying of the lens of the eye. It typically occurs in both of the dogs eyes simultaneously and usually occurs in dogs that have reached six years of age or more. While its appearance is worrisome Nuclear sclerosis does not greatly affect the vision of the dog and treatment is not generally recommended.

HOW DOG CATARACTS DEVELOP

All canine cataracts develop in a similar fashion although there are various causes. A normal dog eye is actually maintained in what is referred to as a dehydrated state. That is to say it consists of 66% water and 33% protein. There is an intricate sodium water pump system in the lens that maintains the all important water/protein balance. When this intricate water pump system in the lens is damaged, the balance alters and extra water moves into the lens. This is accompanied by an increase in the percentage of insoluble protein. These changes result in the cataract formation and the associated loss of transparency.

AGE OF ONSET

The age at which a dog shows signs of developing cataracts is very crucial in identifying the type of cataract. The age of onset may help to determine if the cataracts are hereditary or trauma induced.

CONGENITAL CATARACTS

Congenital dog cataracts present at birth. Congenital cataracts usually occur in both of the dogs eyes. Although one might think that congenital cataracts are inherited this is not necessarily the case as puppies may be susceptible to infections and/or toxins while still in the womb.

DEVELOPMENTAL (EARLY ONSET) CATARACTS

Developmental cataracts start early in a pup’s life and may either be inherited or caused by something in the dogs environment. Inherited cataracts at an early age are more common in breeds such as Standard Poodles, Afghan Hounds and certain terrier breeds.

SENILE (LATE ONSET) CATARACTS

Cataracts that occur in dogs over the age of 6 years are referred to as senile cataracts. Nuclear sclerosis can often be confused with senile cataracts.

INHERITED CATARACTS

Inherited cataracts in dogs may occur on their own or may present simultaneously with other diseases of the eye. Obviously a dog that is diagnosed with inherited cataracts should not be used for breeding.

TRAUMA INDUCED CATARACTS

Trauma resulting from; a head injury, scratch or puncture to the eye surface, shotgun pellet, may damage the lens, resulting in cataract. These cataracts can be very aggressive in their development; within days of the given trauma the white milky appearance may be visible to the owner or tending veterinarian.

DIABETIC INDUCED CATARCTS

When there is excess sugar in the eye fluids, there is excess sorbitol produced. Sorbitol pulls water into the lens which in turn disrupts lens clarity and causes the cataract. Fructose is also produced from the excess glucose and also contributes to the problem. Unfortunately these can be very aggressive cataracts and can induce blindness in a matter of weeks or months in the affected dog.

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