The Eyes Have It

Not long ago I read an article in the December 1994 Cornell Animal Health Newsletter about hereditary eye problems in purebred dogs, and it reminded me of the potentially serious eye problems found in mastiffs. The following is a quote from that article:

"Mastiff: this breed appears particularly prone to known or suspected inherited (eye) defects. In addition to the no-breeding progressive retinal atrophy (PRA) degeneration defect, five breeder-option conditions are seen: entropion, ectropion, macroblepharon, persistent pupillary membranes (PPM), and retinal dysplasia/folds. Six other conditions are currently under study: exposure keratopathy syndrome, which may involve all or part of the cornea; distichiasis; prolapse of the gland of the third eyelid ("cherry eye"); eversion of the cartilage of the third eyelid; cataract; and iris cysts."

The Canine Eye Registration Foundation (CERF) is dedicated to the elimination of heritable eye disease in purebred dogs. CERF attempts to accomplish its goal via registration, research and education. CERF registers purebred dogs of any age that have been examined by a CERF veterinary ophthalmologist and found to be unaffected by major heritable eye disease. CERF recommends that dogs be re-examined every year because some problems, such as PRA, are not detectable by standard CERF exam until dogs are older. CERF publishes a list of registered dogs for each breed. If a dog is found to have a major heritable eye disease the dog cannot be registered and the dog's name is not published but the data is kept by CERF for research purposes. For a list of the eye problems that will and won't pass CERF go to the Eye Problems Found In Mastiffs. There are serious eye problems in mastiffs that will pass CERF, but should not be doubled up on. So, if you are researching the health of a mastiff, ask to see the CERF exam sheet which lists all of the problems that the CERF vet found.

It may surprise you to know that only 173 mastiffs were examined for CERF in 1994. Considering that 1,006 mastiff litters and 3,884 individual mastiffs were registered in 1994, this is a very poor show of concern in a breed with so many eye problems. Note: in 1995, 296 mastiffs were examined for CERF, 1,150 mastiff litters and 4,245 individual mastiffs were registered.

The most alarming eye problem in mastiffs is Progressive Retinal Atrophy (PRA) Type I which is being found in mastiffs more and more frequently. PRA is untreatable and results in permanent blindness. Symptoms of PRA include early loss of night vision followed by day vision, in advanced disease pupillary light reflexes are depressed or lacking, and sometimes cataracts develop. Owners frequently do not notice a change in their dog until their dog is blind. The age when a standard exam can detect PRA and the rate of progression to full blindness varies from dog to dog. PRA can be detected at an earlier age, as early as 8 weeks, using electroretinography (ERG).

PRA Type I is believed to be a simple recessive trait. This means that a dog can "carry" PRA without being affected. An affected dog's offspring will all be affected or carriers of PRA. Statistically, when a carrier is bred to a non-carrier, 50% of the offspring will be carriers. Statistically, 25% of the full siblings of a dog with PRA will have PRA, and an additional 50% will be carriers. The sire and dam of a dog with PRA either have PRA or are carriers of PRA. There will be at least one carrier in every generation of ancestors of a carrier. Affected dogs should not be bred!

I know the pedigrees of eight mastiffs that have been diagnosed with PRA, all from well known show lines. Several of the sires and dams of these mastiffs are unrelated in the first four generations. One mastiff diagnosed with PRA has 11 full siblings that have produced at least one litter and none are registered with CERF. Another such dog's sire has 35 offspring that have produced at least one litter, of these 35, 12 are champions and only one has been registered with CERF. These 35 offspring have themselves produced 46 offspring that have produced at least one litter. I don't know about you, but this scares the hell out of me!

Fortunately, science may be able to help in the near future. Cornell has found the gene for PRA in Irish Setters and developed a test which can determine if an Irish Setter has PRA, carries PRA, or does not carry PRA. This research is being continued to find the genes and develop tests for PRA in other breeds, including mastiffs. For more information go to PRA Research

For more information about CERF and CERF vets, you can call CERF at (765) 494-8179 or go to CERF's web page. CERF eye clinics are often held at dog shows and matches and typically cost between $15 and $20. A dog does not have to be entered to be examined for CERF. My local CERF vet charges $40 per dog examined at her office; she does provide a discount when several dogs are examined during the same visit.

CERF registered dogs are listed in the MCOA Journal. For a list of mastiffs whose CERF exam sheet contains no reference to eye disorders, contact the Mastiff Reporter via Sharon Krauss, 3902 E Cholla, Phoenix, AZ 85028, (602) 494-8234 crestwood@home.com. To get a Mastiff Reporter eye normal certificate and have your dog listed, send a copy of your mastiff's registration and a copy of his normal-normal CERF exam sheet to Sharon Krauss.

Please show your concern for this great breed by having your mastiffs' eyes CERFed.

Thanks for your attention,

Deb Jones

Canine Eye Registration Foundation (CERF)
Dog Genome Project
PRA Research