“Why do the health testing if you just decide to eliminate Dogs from the gene pool? Don’t we do health testing to have the information and education to make the best choices for moving the breed forward?” I am thankful we have veterinarians and geneticists helping us make the best decisions we can for the longevity of our breeds. We could health test all breeds into extinction. The Humane Society of the United States would love that. "
by Pilar Kuhn
Recently, the Humane Society of the United States boasted that 87% of all pets in homes in America have been spayed or neutered. That means that a mere 13% of animals are of breeding capability. In each and every breed of dog there are health tests recommended or required by parent clubs and fellow breeders before considering a dog or bitch for carrying on and taking their foray into the whelping box. The Orthopedic Foundation for Animals works diligently “to promote the health and welfare of companion animals through a reduction in the incidence of genetic disease”. Breeders use their collective information for health research. We use their website to share with puppy buyers the health history behind the puppies they take into their homes.
Last summer we took four littermates for radiographs on their hips and elbows on the same day. For one reason or another, three of the four littermates would not get a “normal” elbow rating from OFA. I was more than surprised. Both parents had normal elbows. All of the grandparents had normal elbows. So why would we expect anything other than “normal” for these offspring? I called a few of my colleagues on the way home and they asked me, “What do these dogs have that could carry forward to improve the breed? How are their hips? Their hearts? Their eyes? Their coats? Their temperament?” I had no hesitation. They all possessed something important that we felt our breed needs to survive. Now we had knowledge; and knowledge is power. Whereas some breeders would choose to spay or neuter these animals and remove them from the gene pool, with our colleagues’ blessings, we chose to keep them in the gene pool and sought out mates that had fully-passed elbow tests.
Just before Westminster this year, OFA posted on Facebook a small blurb and write-up regarding keeping dogs in the gene pool and it used hip tests as an example. “In breeds where the gene pool is limited – that is, breeds that do not have a vast number of breeding animals available and/or those that lack diversity in the pedigrees of available breeding animals – utilizing the dog with Fair hips, assuming the dog is of good or even average quality, is far preferable to further limiting the gene pool by taking the dog out of circulation. One would, naturally, want to ‘breed up’ by using the dog with Fair hips to one with Good or Excellent hips, and then screening the offspring and, in future generations, going forward with the ones that have better hip ratings,” OFA wrote. I recently took the time to talk with Dr. Keller at OFA regarding this very matter and concept of “breeding up”. Together, we looked at their online educational pieces. In case you weren’t aware, there is a document on their website titled, “The Use of Health Databases and Selective Breeding”. http://www.offa.org/pdf/monograph_2012_web.pdf
One of the graphs we reviewed is the Hip Dysplasia graph on Page 9 of the document. It shows the statistical percentage of around 500,000 canines tested and how with each breeding combination, there is a percentage of potential dysplastic progeny. We also reviewed the elbow dysplasia graph on Page 33 and saw similar findings, but based on a much smaller amount of progeny tested – 67,599. Do these findings mean that a dog that doesn’t have a hip or elbow pass will only pass bad hips or elbows? No. But with that information, a breeder can make a choice about what the overall holistic contributions a dog makes for that breed and search for a mate to improve upon the next generation. One of the best ways to assure the health of a breed is to keep the gene pool from shrinking.
Some people have a “slash and burn” mentality about a dog not passing some aspect of a health test. If the two parents have “normal” results but produce some offspring with abnormal results, these people would not only eliminate the offspring, but the parents, the grandparents, and the great-grandparents. This mentality would swiftly wipe out any potential breeding stock. Five years ago I attended a short presentation about the DNA Breeding Tool from Mars Veterinary called Optimal Selection (now in partnership with Genoscope). Veterinarian and geneticist Dr. Angela M. Hughes, DVM worked to bring this tool to the public. I have had the opportunity to speak with her on several occasions about the various advances she and her team continue to make and she was more than excited to share information about their case study with the Dandie Dinmont. The breed was facing extinction. Their gene pool was miniscule. Through DNA comparisons, the geneticists found that the very dogs long-time breeders were avoiding were the ones they needed to get back into their pedigrees to improve the overall health of the breed. Rather than eliminating some dogs, they chose to use them and, in one generation, broadened the gene pool and improved the longevity of the breed.
After spending years caring for, loving, exhibiting, and paying for health tests on a dog or dogs, it begs one to ask the questions, “Why do the health testing if you just decide to eliminate them from the gene pool? Don’t we do health testing to have the information and education to make the best choices for moving the breed forward?” I am thankful we have veterinarians and geneticists helping us make the best decisions we can for the longevity of our breeds. We could health test all breeds into extinction. The Humane Society of the United States would love that. Some people are eliminating animals from the gene pool that may offer something much more far-reaching and we should consider trying to increase that “breeding capability percentage” back up beyond 13%. And, per OFA, the concept of “breeding up” is a reality. The long and the short of it is health testing should be about education, not elimination.
Some people have a “slash and burn” mentality about a dog not passing some aspect of a health test.
There's much to see here. So, take your time, look around, and learn about the health issues of Golden Retrievers. Our Golden Retrievers are cleared of being affected by the 4 Genetic Issues in the List below.
Neuronal Ceroid Lipofuscinosis is a progressive degenerative disease of the central nervous system. In Golden Retrievers, NCL is caused by a two base pair deletion in the CLN5 gene. This causes a frameshift in the genetic coding, leading to a premature termination codon.
Golden Retrievers with NCL begin to develop signs of the disease around 13 months old. Often the first sign of NCL is a loss of coordination during basic movements including walking, running, and climbing stairs. Sings of the disease are particularly noticeable when the dog is excited. As the disease progresses, the loss of coordination becomes evident even when the dogs is calm; the dogs may also experience tremors, seizures, or blindness. Compulsive behaviors, anxiety, and loss of previously learned behavior is also common. Affected dogs may also become agitated or aggressive as the disease continues to progress. Due to the severity of the disease and loss of quality of life, most affected dogs are euthanized by 2-3 years of age.
Because NCL is recessive, a dog must inherit a copy of the mutation from each parent in order to be affected. No signs of NCL will appear if the dog has only one copy of the mutation, although it will be a carrier of the disease. When breeding two carriers together, there is a 25% chance per puppy born that it will develop symptoms of NCL.
Progressive Retinal Atrophy (PRA) is a category of genetic mutations that cause vision loss and blindness. Photoreceptor cells in the retina begin to degenerate, typically progressing from a loss of night vision to complete blindness.
PRA affects many different dog breeds, and these mutations are breed-specific. In Golden Retrievers, two mutations have been identified in addition to prcd-PRA known as GR-PRA1 and GR-PRA2.
Both GR-PRA1 and GR-PRA2 are inherited in an autosomal recessive manner. This means that a dog must inherit a copy of the mutation from each parent to be affected by the disorder. Dogs with one copy of the mutation will not show any signs or symptoms of PRA, however, they can still pass on that mutation to any offspring.
DNA testing is important to ensure that two carriers are not mated together, as carriers of the GR-PRA mutations are asymptomatic. It is generally not recommended to remove carriers from a breeding program to maintain genetic diversity within the breed.
GRMD is a mutation of the dystrophin gene that causes a deficiency of dystrophin proteins in Golden Retrievers. The lack of dystrophin proteins leads to the progressive degeneration of skeletal and cardiac muscles. The disease is similar to the human disease, muscular dystrophy.
Symptoms appear relatively quickly, at about six weeks to two months of age. A dog with muscular dystrophy will exhibit muscle weakness, difficulty standing or walking normally, and difficulty swallowing. Symptoms can range from relatively mild to severe, but GRMD is generally fatal at about 6 months of age.
The GRMD mutation is sex-linked and located on the X chromosome. So while both male and female dogs can be affected, GRMD is mostly a disease related to male Goldens. Females can be carriers of the mutation, however, will not exhibit any symptoms. DNA testing to identify both male and female carriers is important to remove them from the breeding population.
Progressive Rod-Cone Degeneration, or PRA-prcd, is a form of Progressive Retinal Atrophy (PRA) in which the cells in the dog's retina degenerate and die. PRA for dogs is similar to retinitis pigmentosa in humans. Most affected dogs will not show signs of vision loss until 3-5 years of age. Complete blindness can occur in older dogs. Progressive Rod-Cone Degeneration is a form of PRA known to affect over 40 different breeds.
The retina is a membrane located in the back of the eye that contains two types of photoreceptor cells. These cells take light coming into the eyes and relay it back to the brain as electrical impulses. These impulses are interpreted by the brain to "create" images. In dogs suffering from PRA-prcd, the photoreceptors begin to degenerate, causing an inability to interpret changes in light. This results in a loss of vision. Rod cells, which normally function in low-light or nighttime conditions, begin to degenerate first. This leads to night-blindness. The cone cells, which normally function in bright-light or daytime conditions, will deteriorate next. This often leads to complete blindness over a period of time.
PRA-prcd is inherited as an autosomal recessive disorder. A dog must have two copies of the mutated gene to be affected by PRA. A dog can have one copy of the mutation and not experience any symptoms of the disease. Dogs with one copy of the mutation are known as carriers, meaning that they can pass on the mutation to their offspring. If they breed with another carrier, there is a 25% chance that the offspring can inherit one copy of the mutated gene from each parent, and be affected by the disease.
As DNA tests become available for milder conditions, breeders will be forced to avoid pro-ducing dogs with any diseases. “We are going to be pushed into making poor decisions for the breed, such as removing dogs from the gene pool for minor conditions, “Fortunately, ichthyosis does not affect a dog’s ability to hunt, retrieve, swim or participate in all kinds of activities. It is so important to not lose dogs with great qualities. A DNA test can be helpful as long as we use smart breeding.”
“Breeders should not remove affected or carrier dogs from the gene pool,” “This would reduce genetic diversity and create a super bottle neck. ”The best approach is to gradually reduce the mutation over six or seven generations. “You should consider the entire dog — all his or her qualities and characteristics. An affected or carrier dog that has much to contribute should be bred, although you should avoid breeding two affected dogs. Instead, breed outstanding affected or carrier dogs to clear dogs. This provides a choice of dogs to progressively decrease the frequency of the PNPLA1 gene mutation. ”The Golden Retriever Club Of America Health & Genetics Committee endorses this approach.
Ichthyosis is a condition characterized by scaly skin and dandruff. It does not cause itching, scabbing, or hot spots. Ichthyosis is not the same thing as allergies. In Golden Retrievers, it is usually very mild. However, in other breeds it can be much more severe. The Golden Retriever Club of America says that it is a rare condition even though a high percentage of dogs are testing positive for it. A few breeders are making a big deal out of it. Most don’t test for it at all. We, along with a growing number of other breeders are taking a middle of the road approach. We do the test and use the results in making good breeding decisions. At the same time, we feel that this is a minor issue and that there are many other concerns that are more important.
What is Ichthyosis and How Does It Affect a Dog?
Ichthyosis is doggy dandruff. When a dog has symptoms, those symptoms are usually a light flaking of skin. There can, however, be a wide range of possibilities with regard to the severity of the condition. Many dogs that receive DNA results that indicate that they are affected with Ichthyosis have no flakes or any other kind of skin problem. Some dogs with Ichthyosis have a light flaking of skin, most noticable when brushing. It does happen at times, however, that Ichthyosis is bad enough for there to be a constant flaking of skin. Even then, it is more of a nuisance to the owner than a bother to the dog. A severe case could cause a dog to leave flakes of skin wherever he sits or lies. These cases are not common. By far, the majority of Golden cases are very mild.
Ichthyosis is not anything like allergies that many Golden Retrievers suffer from. Ichthyosis very rarely bothers a dog. It doesn’t cause itching or scabbing like allergies. Ichthyosis in Golden Retrievers whether in its mildest form or its most severe is simply dandruff or flaky skin.
The condition isn’t curable. However, it is usually well-controlled with brushing, mild shampoos and conditioners, and a diet high in fatty acids. I have heard of several affected dogs who had flakes to totally disappear after just a change in diet. The type dog food being fed greatly affects the expression of Ichthyosis.
Ichthyosis is a recessive trait. This means that both parents have to carry the Ichthyosis form of this particular gene for expression of it. If either parent is clear, there is no chance of any puppies being affected.
There are three possible results of the DNA test, affected, carrier, and clear.
If both parents are carriers, 25% of the puppies will be affected. In this case, 50% will be carriers, and 25% will be clear. This does not necessarily mean that 25% will be clinically affected. This means that a DNA test will show them to be carriers of 2 copies of the gene. They could have clinical symptoms.
In cases where one parent is a carrier and one is affected, 50% of the puppies will be DNA affected. Again, this doesn’t mean clinically affected.
If both parents are DNA affected, all puppies will be DNA affected. A dog that is a carrier will have no chance of having the condition, either by DNA test or clinically. A carrier is simply a dog with only one copy of the defective allele for the gene. Two copies are needed for a dog to be DNA affected.
The statistics on the percentage of Goldens with Ichthyosis according to the DNA test would be quite disturbing if the statistics for the number of Goldens with actual symptoms matched those DNA statistics.
There is, however, a huge difference between the two. The DNA statistics from Antigene, a testing company says that 30% of Goldens are affected by Ichthyosis. However, the Golden Retriever Club of America says that Ichthyosis is rare and that less than 1% of all skin conditions in the breed are caused by Ichthyosis. Wow! What a difference in the statistics! 1% of dogs with skin disorders or 30% of all dogs. The difference between the 1% and the 30% represents those dogs who have no symptoms or with symptoms so mild that no one knows they are there.
Further information from Antegene says that 40% of Golden Retrievers are carriers and only 30% are clear. When the number of dogs that are either carriers or affected are broken down by the area of the world, 61% of Golden Retrievers in America are carriers, 52% in Australia are carriers, and 83% of Golden Retrievers in Europe are carriers.
For English Golden Retriever breeders trying to have breedings clear of Ichthyosis, finding quality Goldens in the 17% that are clear of Ichthyosis is a challenge. To do this would undoubtedly reduce the gene pool tremendously and all for the sake of eliminating a condition that the Golden Retriever Club of America says is rare and mild, for a condition whose symptoms don’t bother the dog, for a condition that is easily controlled by a healthy diet, regular brushing, and using mild shampoos (all things that we should be doing for our dogs anyway), for a condition that is responsible for less than 1% of all skin conditions in Golden Retrievers, and for a condition that many veterinarians have never heard of.
I have seen in talking to others and in reading that dogs with clinical cases of Ichthyosis do tend to reproduce those symptoms. Also, dogs with a positive DNA test but with no symptoms tend to produce symptom-free puppies. Keeping this fact in view is key in wisely using the DNA test.
The more prudent approach to breeding away from Ichthyosis is to breed unclear dogs in lines who have clinical cases of Ichthyosis only to clear dogs, to pursue a goal of eliminating the condition all together over 6 -8 generations, to use the DNA test in making good breeding decisions, to continue doing the test and using the results wisely, to be open and honest to the public about what you have, and to use good common sense about it realizing that there are other issues in our breed that need greater attention.
If too much importance is focused on this mild skin condition, our breed would have 1% less skin problems but would be full of dogs with other health problems, poor temperaments, narrow unsightly heads, and poor conformations.
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