Genetics and Health Testing for Doodles
Dogs that sire or birth puppies here at Westwood Labradoodles, Goldendoodles and North American Retrievers all receive acceptable results on the following health tests before they are bred: PennHIP, OFA, CERF, prcd-PRA, and von Willebrands diesease.
You don't need a degree in genetics, or even a college course, to understand the basics of health testing in Labradoodles or Goldendoodles. But a good Labradoodle breeder or Goldendoodle breeder will have a pretty good handle on the genetics involved with the health of these hybrids though, and be able to explain them to you!
Every aspect of your Doodle's physical being began as contributions from its parents' bodies, carried in their genetic code. There are certain health conditions in Golden Retrievers, Poodles and Labrador Retrivers which can be passed from parent to puppy in the genetic material and hence are found in Goldendoodles, Labradoodles, and Double Doodles (North American Retrievers). These conditions are called' heritable' (that is, "able to be inherited") disorders.
There are 2 disorders, Von Willebrand's Disease ( a bleeding disorder), and prcd-PR (an eye disorder) in which we actually know what gene is responsible. In the case of these diseases, a laboratory test can determine if, or how many copies, of the gene are present. A dog having two copies of the gene for either disorder would eventually be affected by the disease and would not be bred. A dog with one copy is a carrier, and a breeder would take care to breed that dog only to a dog that is NOT a carrier. Carriers remain perfectly free of these disorders, the only concern is them passing it to a puppy that receives a second copy from the other parent. A dog is only affected by the disease if they have 2 copies. In all other instances we cannot look for a gene to tell us of the presence of a certain disease. We have to look for evidence of the disease itself. In the case of heritable eye diseases in Poodles, Labradoodles, and Goldendoodles, for example, an exam is conducted by a veterinary opthamologist every year to determine if a disease is developing. Dogs that show symptoms of a heritable eye disease are eliminated from the breeding program. Other examples of heritable diseases tested for by some Doodle breeders include thyroid disease, some forms of heart disease, Addison's disease, sebaceous adenitis, hip dysplasia and diabetes.
The heritable disease found in Doodles that most people seem familiar with is Hip Dysplasia (HD). This disease is a sort of Degenerative Joint Disease (DJD) , with symptoms similar to arthritis in humans. In dogs though, the heritable form of the disease is not a disease of old age, but can develop while the dog is still quite young and is obvious on X-rays as the hip joint has abnormal features. As with most things, the hip architecture can range from great to horrible, with some hips in between. Two schemes are commonly available in the US for evaluating hips. OFA screening relies on veterinarians reading an x-ray and assigning a rank: 'Excellent', 'Good', 'Fair'. 'Borderline' or 'Dysplastic'. This rank is based on the shape of the hip socket and ball joint. Labradoodle breeders who base decisions about breeding on OFA generally agree that 'Excellent' and 'Good' rankings are fine to breed, and also agree that 'Borderline' or 'Dysplastic ' are not acceptable for breeding. As with all other decisions where there are gray areas, some breeders will breed a dog with a 'Fair' rank, and others will not. Some will breed a 'Fair' under some circumstances and not others. This is really a judgement call and not all breeders agree. There is a registry (www.offa.org) that collects and reports hip assessments to assist in recording and tracking these rankings. OFA will not certify a dogs hips until the age of 2 years, although the will offer a preliminary opinion before that time.
However, some breeders are using a specialized x-ray technique called PennHIP testing, which can be done as young as 4 months of age. This test results in a score for each hip, ranging from .1 to .9, and reflects how tight the hip joint is, and the average score varies by dog breed. Tighter hips, that is lower scores, are less likely to develop DJD and are desirable in any breeding dog. In my opinion, any score under .4 is clearly breedable. Anything over .65 i s generally considered not breedable. In between .4 and .65 is a gray area. Breeders who utilize this method track the average scores for their breed, and try to breed only dogs with average or better-than-average scores. For example, the average hip score for Standard Poodles is currently .5. If a Poodle were to score .42, in the middle zone, it would be considered breedable by most because it is better than average. However .42 would NOT be considered breedable by most Borzoi breeders because that breed average is .19! So some breeders do OFA testing, some do PennHIP testing, and some do both. My personal opinion is that there is value in doing both tests, as they do look at somewhat different features of hip health. It can assist in choosing mates for a dog if you know the details of the hips. If a dog has great hip conformation (OFA 'Good' or 'Excellent') but the hips are a little lax, maybe in the .5-.6 range, one might consider an OFA 'Fair' mate if the hips are really tight, possibly in the .3 range.Mini-Labradoodles are at risk for slightly different problems as they are bred from Miniature Poodles instead of Standard Poodles. For example, the incidence of hip dysplasia is so low in the Minis that some breeders choose not to test for it. So breeders may test for some or all of these diseases. Some breeders do not test at all. If testing for heritable diseases is important to you it should be among the questions you ask of prospective breeders.
Another way breeders try to eliminate HD and other heritable diseases from their breeding lines is to examine their dog's pedigrees carefully. Looking at hip assessments and other health records of relatives (grandparents, siblings, half-siblings, cousins, etc) and choosing breeding stock with the healthiest background possible is all part of the picture. One of the difficulties in trying to eliminate heritable disorders in dogs is that most of the genes that cause the disorders are what are termed 'recessive'. This means they are hidden, or masked, by other genes. A parent that does NOT show the disease, but is carrying the gene, can pass that gene carrying the disease to a pup. If BOTH parents happen to be carriers and pass the genes to a pup, the pup can have TWO defective genes and will show the disease. This is similar to 2 brown-eyed parents having a blue eyed child. Blue is recessive, but if both parents are blue carriers, they can have a blue -eyed child. Some heritable diseases are passed in this manner, via a single recessive gene.
Complicating this picture in the case of HD is the fact that hip dysplasia appears to be controlled by several genes, so predicting it's inheritance is even more difficult. It IS possible to have 2 parents with good hip scores, or good hip x-rays that produce a puppy with hip dysplasia. In addition to testing members of a breeding pair, breeders will gather testing information on relatives of their breeding pair. The scores of parents, grandparents, siblings, siblings of parents, and even puppies produced from previous litters will all be examined. In some cases it is better to breed a dog with slightly below average hips, if the test results for all relatives are excellent, than to breed a dog with good hips who has HD in its pedigree. So interpreting test results is no easy task! This is true for the other heritable diseases passed as recessive traits as well.But Doodle breeders who test their breeding stock do the best they can. They use their dogs test results to help make the best pairings possible in their breeding decisions. The hope is to reduce the number of Doodle pups born with hip dysplasia by removing dogs from the breeding population that have clearly substandard hips, and by following the offspring of dogs with hip scores in the middle ranges to see if their pups remain healthy. We do the same for all diseases that are known or suspected to be heritable in Labradoodles and Goldendoodles.
Author: Helene Roussi