Cataracts in Dogs

By Malcolm Weir, DVM, MSc, MPH; Ernest Ward, DVM

What is a cataract? 

Inside the eye is a lens that focuses light on the back of the eye or the retina. Vision occurs at the retina. The structure of the eye is similar to a camera, which has a lens to focus light on the film. A cloudy or opaque lens is called a cataract.

What causes cataracts?

The most common cause of cataracts in the dog is inherited disease. Other causes include injuries to the eye or diseases such as diabetes mellitus ("sugar diabetes"). Some cataracts appear to occur spontaneously and are age related.

Are some breeds more prone than others?

Hereditary cataracts can affect many breeds of dogs. Breeds that are considered to be more susceptible to cataracts include the American Cocker Spaniel, Labrador Retriever, French Poodle, Boston Terrier and the Welsh Springer Spaniel to name a few.

Will my dog go blind?

If cataracts occupy less than 30% of the lens or if only one lens is affected, they rarely cause diminished vision. When the opacity covers about 60% of the total lens area, visual impairment often becomes apparent. If the opacity progresses to 100% of the lens, the dog will be blind in the affected eye. However, whether the cataract remains static or progresses will depend on the type of cataract, the breed and other risk factors.

  • Cataracts may also be described as incipient, immature, mature, and hypermature.
  • Incipient – so small it often requires magnification to diagnose. These involve less than 15% of the lens and cause no visual deficits.
  • Immature – involves greater than 15% of the lens and often involves multiple layers of the lens or different areas. The retina can still be seen during examination and visual deficits are typically mild.
  • Mature – involve the entire lens and the retina cannot be seen during examination. Visual deficits are often significant with blindness or near-blindness often observed.
  • Hypermature – the lens begins to shrink and the lens capsule appears wrinkled. Lens-induced uveitis (inflammation within the eye) often occurs at this stage.

Can anything be done to prevent my dog from going blind?

"Veterinary ophthalmologists can surgically remove cataracts and restore failing vision..."

Veterinary ophthalmologists can surgically remove cataracts and restore failing vision caused by cataracts in your pet. Most pets have few complications and return to normal activity, running and playing within just a few days of the surgery. Your veterinarian can arrange a referral appointment to an ophthalmologist to further evaluate your pet's condition and determine appropriate treatment options.

To date, no topical medications (i.e., drops) have been shown to delay cataract progression, although topical aldose reductase inhibitors (ARIs) have shown some effectiveness in cataracts brought on by diabetes. These drugs may be prohibitively expensive, however, and must be given every 8-12 hours with no interruption in treatment to be effective.

How old will my dog be if he does go blind?

Since cataracts often have a hereditary cause, cataract progression varies from breed to breed and individual to individual. Cataracts may develop relatively early in life in some breeds; in others, the first signs are detected when the dog is older and progression is so slow that dogs still have reasonable sight well into old age.

If the condition is hereditary, what can be done to prevent it from being passed on?

"Prevention is better than cure."

This is a situation where prevention is better than cure. Many veterinary ophthalmologists offer Eye Certification Programs that offer breeders the opportunity to screen their breeding stock and make sure they are producing disease-free puppies.

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