EYE DISORDERS

Eye testing should be done yearly by a certified examiner for the CERF (Canine Eye Registration Foundation). Affected dogs should not be used for breeding. Vitamin E is suspected of preventing eye ailments, and in the case of nutritional-based cataracts, prevention includes supplementing milk replacers during weaning with high quality puppy food. (ie. Eukanuba Weaning Diet - for puppies 3-8 weeks).

The diseases below affect many breeds - although Boxers may not be listed as "predisposed", it does not mean that the breed is clear. Breeders must test using a certified canine opthomologist to determine whether or not a dog has normal eyes.

Glaucoma

Glaucoma is a increase in the intra-ocular pressure (IOP) that is incompatible with the health of the eye. "Primary glaucoma" is hereditary, and usually breed-related. Predisposed breeds: Poodles, American & English Cockers, English Springers, Arctic breeds (Huskies, Malamutes, Elkhounds, Samoyeds, etc.), Shar-Pei, Bouviers, Basset Hounds, Beagles, Chow Chows, Afgans, Dalmatians. 

When glaucoma is "primary", it often signifies that the opposite, unaffected eye is also at risk of developing glaucoma, most likely within 2 years following the diagnosis of the first eye. Primary glaucoma is not associated with any other ocular disease. "Secondary" glaucoma is not inherited - it is the result of some other event in the eye. It is very important to determine the cause for the glaucoma, as treatment will vary, and secondary glaucoma could be caused by a systemic disease that can threaten the dog's life.

Diagnosis requires the measurement of IOP (in mmHg) using a Schiotz tonometer or a Tonopen. The pressure is evenly distributed in the eye, and the pressure on the inner cornea equals the pressure on the retina. Normal IOP is 15-25mmHg; glaucoma measures greater than 25-30mmHg. Specific clinical signs in the eye can be observed, and immediate veterinary treatment is necessary, as this condition is very painful. Yearly eye exams are beneficial in pinpointing any eye disorders and enabling early treatment to be given. If glaucoma is left untreated, vision will be completely lost.

Cataract

A cataract is an opacity of the lens resulting from changes in lens protein composition or disruption of lens fibre arrangement. Any loss of transparency, regardless of size, location, or extent, is a cataract. The most common cause of cataract is hereditary, but it is also caused by diabetes, trauma to the eye, nutritional deficiencies in puppy hood, electric shock (ie. from chewing an electrical cord), radiation therapy (especially gamma), and certain drugs. The degree of visual impairment is dependent on the extent of cataract development in the eye(s). Surgical removal of the cataracts can be done, and prevention includes yearly testing (CERF exams - Canine Eye Registration Foundation), and the removal of affected animals from the breeding program. Nutritional based cataracts can be prevented in puppyhood by supplementing commercial milk replacers with a blenderized puppy weaning diet. Esbilac is the most commonly implicated nutritional cataract. If fed exclusively for the first 1-3 weeks of life, studies have shown that the risk of nutritional-based cataracts increases.

One out of every 25 Australian Shepherds are affected with cataracts, and it is suspected that as many as one-third of the breed carry genes for this potentially blinding eye disease. Visit these two web sites for more information on cataracts.

http://aussie-health.westga.edu/research/cataracts/index.html

http://aussie-health.westga.edu/research/cataracts/development.html 

Progressive Retinal Atrophy (PRA)

This eye condition affects many breeds, especially Irish Setters, Gordon Setters, Poodles, Norwegian Elkhounds, Samoyeds, Yorkshire Terriers, Giant Schnauzers, and Welsh Corgis.

PRA is characterized by degeneration of the cells of the retina, gradually leading to an eventual loss of vision. The disease occurs usually later in life (5-7 years), and the first noticeable signs are the dog hesitating to go out at night, or has difficulty navigating around a darkened room. The dog also may up, but not down, stairs, and other behavioural changes can occur.

Studies have shown that PRA is a recessive trait, therefore, 2 dogs bred to each other who do not show clinical signs, but are carriers of PRA, can pass it to their offspring. Dogs who have PRA should not be used for breeding. Locating carriers of this (or any other) disease can be difficult. Testing of breeding stock should be done through CERF (the Canine Eye Registration Foundation).

Central Progressive Retinal Atrophy (CPRA)

This eye condition is closely related to PRA. It affects the pigment cells in the center of the retina, and the dog's central vision is lost. Dogs with CPRA find it difficult to see stationary objects, but can see movement with the periphery (outer edge) of the retina. This disease has been observed in Labradors, Shelties, Border Collies, Coon Hounds, and others. Testing of breeding stock should be done through CERF, and affected dogs, or known carriers, should not be used for breeding.

  Inherited Disorders of the Eye