Cataracts, progressive retinal atrophy, glaucoma, and collie eye anomaly are some of the hereditary eye diseases found in dogs. These diseases and others can be tested for before a dog is bred. If you're buying a purebred puppy and the breed you're interested in is prone to eye disease, ask the breeder if the pup's sire and dam are registered with the Canine Eye Registry Foundation (CERF). CERF registers dogs that are free of heritable eye disease as certified by a veterinary ophthalmologist. Check the date on the CERF certificate. Dogs must be recertified annually to maintain their registration.

Juvenile Cataracts

The lens of a dog's eye is normally transparent. A cataract is an opaque spot on the lens. Dogs often acquire cataracts with age, but juvenile cataracts, which develop before six years of age, are hereditary. Juvenile cataracts may remain small, causing little interference with vision, or they can progressively grow larger, leading to blindness. They may start in only one eye but eventually affect both eyes. More than seventy-five breeds are prone to juvenile cataracts. Researchers are working to develop genetic tests to identify the carriers of cataracts in those breeds.

Progressive Retinal Atrophy

Progressive retinal atrophy (PRA) is an umbrella term for a group of hereditary eye diseases that affect more than eighty breeds. While PRA has the same general effect in all breeds, genetic mutations result in some differences among breeds as far as the age of onset and the speed at which the disease progresses. Types of PRA are early onset slow progression, early onset rapid progression, late onset, and sudden acquired retinal degeneration. The disease is inherited through a recessive gene.

The firstsign of PRA is night blindness, reluctance to go outside at night, or to move around in a dark room. Depending on the type of PRA, the dog may retain day vision for a while or become blind very quickly. There's no treatment for PRA, but researchers have identified a genetic marker that will help them develop a DNA test to identify normal, affected, or carrier dogs at an early age.

Glaucoma

The eye contains fluid that is slowly and continuously released from the eye. When the eye produces fluid faster than it can be released, pressure builds up within the eyeball. This condition, called glaucoma, damages the optic nerve and results in blindness if left untreated. Dogs can have primary glaucoma, which is hereditary, or secondary glaucoma, which occurs as a complication of some other eye disease.

Among the breeds that are prone to primary glaucoma are beagles, cocker spaniels, basset hounds, and Samoyeds. Any dog that has a hereditary predisposition to glaucoma should be examined annually by a veterinary ophthalmologist so the condition can be identified and treated as early as possible. Medication is available to help remove fluid from the eye or to reduce fluid production. When medication isn't effective, surgery can sometimes help.

Collie Eye Anomaly

Rough and smooth collies, Border collies, and Shetland sheepdogs may develop a condition called collie eye anomaly (CEA), which is a disease of the deep structures of the eye. Dogs are born with CEA, and it can be diagnosed by a veterinary ophthalmologist with the aid of an ophthalmoscope as early as four to eight weeks of age. CEA affects the development of the choroid, which provides the retina with oxygen and nutrients. Sometimes the choroid suffers only minor damage with little effect on a dog's vision, but in other cases retinal detachment results in blindness. CEA is inherited through a recessive gene, so make sure you purchase a puppy whose parents have up-to-date registrations with CERF and have never produced puppies with CEA.