Causes of Canine Cataracts

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Causes of Canine Cataracts

A variety of factors from genetics to nutrition to age can affect your dog's likelihood of contracting cataracts. Learn the causes of this condition.

Cataracts occur when an opacity develops in the clear lens of a dog’s eye. This opacity prevents the lens from directing light to the retina, causing sight issues. Some opacities are small and will not affect your dog’s vision. But mature cataracts, opacities that are dense or large, will strongly affect sight.

There are several reasons these opacities develop in one eye or both eyes. Common causes of cataracts include:


Genetic disposition to cataracts is the most common reason dogs develop this eye condition. Both male and female dogs are equally prone to cataracts, but certain breeds are more predisposed to them.

Dog breeds that commonly pass down cataracts include:

Though these breeds have hereditary disposition to cataracts, any breed as well as mixed breed dogs can develop them.


A significant proportion of dogs with diabetes will develop cataracts. Dogs with diabetes develop cataracts soon after becoming diabetic due to high glucose levels, and in many cases, the cataracts will grow aggressively and require swift medical attention.


Aging dogs, around eight years old and older, may begin to develop abnormalities in the eyes. Most dogs that develop cataracts in old age, however, will have smaller ones that will not impair vision significantly.

Toxic cataracts

Ocular diseases such as retinal degeneration or intraocular inflammation (uveitis) cause a toxic reaction in the lens, making the lens “sick.” In such cases, cataracts may develop.

Lens trauma

Penetration or a blow to the eye may rupture lens capsules. Ruptured lens capsules can begin to form cataracts and severe uveitis. In many cases, pet owners will not realize that lens capsules have been ruptured, and the intraocular inflammation will not manifest until weeks after the initial injury, so it is important to seek veterinary care after any eye injury.

Nutritional deficiencies

Dogs deficient in key nutrients, especially puppies, can develop cataracts. In the case of malnutrition, the condition can improve once the diet is adjusted.

No matter what the cause, if symptoms of cataracts begin to show, it is important to have your dog’s eyes checked out by your vet.

  • Cataract
  • Diabetes
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