Screening Dogs for Inherited Health Problems
Know About Breed-Specific Genetic Problems Before Buying a Dog
All dogs, whether purebred from the best champion lines or mongrels of totally mixed background, can carry inherited genetic diseases. The only difference with purebreds is that reputable breeders have their breeding stock tested clear of genetic disorders before the dog is used for breeding.
Each breed of dog has its own set of genetic illnesses. Some breeds have many, while others have only a handful. Some problems are common to a large number of breeds, while others are confined to a few, so not every breed will require the same health clearances.
Before buying a dog, do some research and see what problems are found in the breed you have chosen and what tests breeders should be doing to produce healthier puppies.
Health Testing is Essential When Breeding Dogs
For some problems, there are DNA tests that can reveal whether a dog is a carrier or will be affected later in life with a particular genetic problem. Breeders can use this as a tool to ensure no puppies will end up affected, or even to completely eliminate those genes from their breeding stock.
But with many problems, there is no DNA test to find a carrier. A dog that is healthy and appears normal could be a carrier of a hidden inherited defect, and if bred to another carrier of the same defect, some of the puppies could be affected. Then all the breeder can do is check every generation of dogs to be used for breeding and only breed from unaffected ones and from dogs those that have not produced affected puppies in a previous litter. This will reduce the risk of future health problems.
Some illness are partly genetic and partly environmental, and some are caused by combinations of several genes, so eliminating genetic diseases is always a struggle. But good breeders do everything they can to breed only from healthy stock.
Some of the more common tests are to detect heart disease, blood disorders, thyroid problems, hip dysplasia (dislocated hips, or HD), dwarfism, allergies, autoimmune problems, epilepsy and eye diseases such as progressive retinal atrophy (PRA) and inherited cataracts.
Dogs Should Have These Health Clearances
Breeds subject to HD should have all breeding stock cleared by hip x-rays, which are then sent to a facility such as the Orthopedic Foundation for Animals (OFA) for evaluation. Dogs with normal hips are assigned a number and are listed as Excellent, Good, Fair or Borderline. If dysplasia is seen, the hips will be assigned a grade indicating how bad the problem is. Veterinary colleges may just state Normal or Affected. Dogs tested overseas will be graded differently, but OFA has a chart where you can compare and understand all the grades. A breeder should be able to show you proof that the parents and preferably several previous generations of a dog or a litter have normal hips.
Eye tests are commonly recorded at CERF (Canine Eye Registry Foundation), and Opti-Gen, which is a DNA testing facility.
Most other health tests will be certified by a veterinary specialist or veterinary college, but some breed clubs may keep their own list of dogs that have health clearances for diseases that are considered a problem in that breed. OFA and Opti-Gen also have databases for additional health problems such as heart disease.
For a detailed list of many different breeds and the genetic disorders found in each one, the Canine Inherited Disorders Database in Canada is an excellent resource. You can also look up a national or regional club for the breed you are considering in order to obtain information on specific problems in that breed.
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