What is ... ?: 

 A cataract is any opacity or loss of transparency of the lens of the eye. The opacity may be confined to a small area of the lens or capsule, or it may affect the whole structure. A complete cataract affecting both eyes will result in blindness, whereas small non-progressive cataracts will not interfere with vision. Primary cataracts occur in some breeds; in other breeds the cataract may develop secondarily to another inherited disorder such as progressive retinal atrophy or glaucoma.

How is ... inherited?: 

The genetics have not yet been defined for most affected breeds. In others, the mode of inheritance is autosomal recessive, autosomal dominant, or with incomplete dominance.

What does ... mean to your dog & you?: 

 This depends on whether the cataracts are localized to a small area or are more general, and whether they affect one or both eyes. A small cataract in one eye will not affect your dog's vision at all. At the other end of the spectrum, cataracts may progress rapidly or slowly to cause complete blindness.

Congenital cataracts or those that develop at a young age may mature and be reabsorbed, resulting in improved vision. This is unpredictable. In the process of resorption, liquefied lens material may leak into the eye causing inflammation and possibly glaucoma.
With their acute senses of smell and hearing, dogs can compensate very well for visual difficulties, particularly in familiar surroundings. In fact owners may be unaware of the extent of vision loss. You can help your visually impaired dog by developing regular routes for exercise, maintaining your dog's surroundings as constant as possible, introducing any necessary changes gradually, and being patient with your dog.

How is ... diagnosed?: 

 You may suspect your dog is having visual difficulties and/or you may notice discoloration of your dog's pupil(s). Your veterinarian will be able to see the cataract with an ophthalmoscope. Even when not causing visual problems, cataracts may be discovered on a routine ophthalmoscopic exam.

How is ... treated?: 

 Cataracts can be removed surgically. The decision whether to do so is based on several factors, such as whether the cataracts are progressive, the degree of visual impairment, and the dog's temperament. To prevent postoperative problems, the dog must be cooperative and quiet, especially in the first week following surgery.

Breeding advice: 

 It is prudent to assume cataracts are inherited unless another specific cause can be identified. Since some cataracts cause no clinical signs, it is worthwhile to screen dogs of affected breeds annually that are used in breeding programmes. Where cataracts are identified, affected animals, their parents and littermates should not be used for breeding.

The fact that the age of onset is fairly specific for different breeds is helpful in making decisions about breeding programmes.


 American College of Veterinary Ophthalmologists. 1996. Ocular Disorders Presumed to be Inherited in Purebred Dogs. Purdue University, W. Lafayette, Indiana.

What breeds are affected by ... ?