EDUCATION OR ELIMINATION

 

             

Health Testing – Education or Elimination?


“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.

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Some people have a “slash and burn”  mentality about a dog not passing some aspect of a health test.

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Important Information about the health of Golden Retrievers

What you need to know

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 (NCL) in Golden Retrievers

Neuronal Ceroid Lipofuscinosis (NCL) in Golden Retrievers

Neuronal Ceroid Lipofuscinosis (NCL) in Golden Retrievers



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.

PRA GR-PRA1 & GR-PRA2

Neuronal Ceroid Lipofuscinosis (NCL) in Golden Retrievers

Neuronal Ceroid Lipofuscinosis (NCL) in Golden Retrievers

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.

Muscular Dystrophy in Golden Retrievers (GRMD)

Muscular Dystrophy in Golden Retrievers (GRMD)

Muscular Dystrophy in Golden Retrievers (GRMD)

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.            

Muscular Dystrophy in Golden Retrievers (GRMD)

Muscular Dystrophy in Golden Retrievers (GRMD)

Progressive Retinal Atrophy or PRA-prcd.. 


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.

Ichthyosis-A (ICH-A)

Studies show that 50% of Golden Retrievers are ICHTHYSIS Carriers... Learn More Below...

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 a Cosmetic Issue.  It Is Not the Same as Allergies.


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. 



What is the Significance of the New DNA Test?

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.


Statistics and Frequency of Ichthyosis in Golden Retrievers

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. 


Only 17% of Golden Tested in Europe Were Found to Be Clear


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.

Some Affected Dogs Have Clinical Cases with Symptoms; Other Affected Dogs Have No Evidence of It!!!


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.