Progressive Retinal Atrophy is an inherited form of blindness in dogs. The various forms of PRA are typically breed-specific, with clinically affected dogs of the same breed usually sharing an identical mutation. Geneticists at the Kennel Club Genetics Centre at the Animal Health Trust have discovered a mutation that causes a form of progressive retinal atrophy (PRA) in Tibetan Spaniels. It is referred to as PRA3 to distinguish it from other, genetically distinct, forms of PRA that are caused by different mutations.
Testing is now available for PRA3 for Tibetan Spaniels.
|Genetically Affected||These dogs have two copies of the PRA3 mutation and will almost certainly develop PRA during their lifetime.|
|Carrier||These dogs have one copy of the mutation and one normal copy of DNA. These dogs will not develop PRA themselves as a result of the PRA3 but they will pass the mutation on to approximately 50% of their offspring. We cannot exclude the possibility that carriers might develop PRA due to other mutations they might carry that are not detected by this test.|
|Clear||These dogs have two normal copies of DNA. Clear dogs will not develop PRA as a result of the PRA3 mutation, although we cannot exclude the possibility they might develop PRA due to other mutations they might carry that are not detected by this test.|
What are the signs to look for?
The earliest clinical sign is “night blindness.” The dog cannot see well in a dimly lit room or at dusk. The dog will show a reluctance to move from a lighted area into darker surroundings. The night blindness develops progressively into complete blindness.
How can you know for sure your dog is affected with PRA?
Genetic testing for PRA3 is now available through Canine DNA Testing at Animal Health Trust in the UK. You can order your test online.
The only way to be sure is to have your dogs eyes examined by a Veterinarian who specializes in Ophthalmology. Once examined and found to be clear from PRA, the dog is registered (in the United States) with CERF – Canine Eye Registration Foundation.
Is the CERF registration good for life?
No, CERF registration is good for twelve months from the examination date. It does not indicate whether or not the dog carries the PRA gene.
How do you prevent PRA?
It is advisable for all breeding dogs to have their eyes clinically examined by a veterinary ophthalmologist prior to breeding and throughout their lives, with at least one examination occurring when the dog is at least 8 years of age, so that any cases of PRA caused by additional mutations can be detected and that newly emerging conditions can be identified.
“Weeping Eyes” is one of those symptoms that can be the result of any number of different causes. Some tearing in Tibbies is attributable the natural configuration of the face. What apparently happens is the fullness of the face may push the facial hair against the eyes, irritate then and cause tearing. Some of the tears drain away through the nose (as they are supposed to do) but when there are a few too many tears, there’s no place for them to go except to overflow those tight lower lids onto the face. Facial hair also sometimes acts like a “wick” to draw the tears onto the face. In most cases this really isn’t anything to worry about with no consequence other than cosmetic.
Another cause of weeping eyes is allergies, often to dusts and pollens. The discharge is usually watery, and when you pull down the lower eyelids, the insides are quite inflamed and red. Sometimes there is sneezing as well.
Another is irritation, such as from dirt or sand. The weeping is just from the particles getting into the eye and rubbing on the tissues.
Bacterial conjunctivitis is also another possibility.
NOTE: If there is ever any question, you should have your pet examined by your vet or a veterinary ophthalmologist.
“Cherry Eye” is actually a prolapsed third eyelid. What happens is that the eyelid becomes “loose” allowing one of the tear glands to protrude. Tacking is the recommended procedure that should only be done by a qualified vet or a veterinary ophthalmologist.