Genetic testing for breeding dogs?

Should dogs be genetically tested before having puppies?



Introduction

A question for our dog breeder’s round table. . . .

Breeders participating in the round table have different levels of experience with different breeds, but have several things in common: they study their breeds, produce dogs that participate in dog sports and activities, protect breed health by using genetic screening for disease and structural abnormalities, and care more about the quality of the home for a puppy than for the money or prestige it brings.

Dogs are susceptible to more than 300 genetic disorders, some serious, some mild, some inconsequential. Some inherited abnormalities are specific to certain breeds or groups of breeds: copper toxicosis is a problem in Bedlington Terriers, bladder stones affect Dalmatians, Fanconi disease attacks Basenjis, and Collie eye anomalies affect the Collie breeds. Inherited diseases or structural problems such as hip dysplasia, glaucoma, sebaceous adenitis (a skin disease), various heart ailments, and more tend to affect many breeds of dogs.

Some inherited abnormalities are minor and require correction but do not affect the dog’s life. Included in this group are inverted eyelids, hernias, and mild tooth misalignments. Some are life-long but can be controlled with medication. Inherited thyroid disease falls into this category.

Researchers are working hard to identify the genetic origin of canine diseases so they can be excised from breeding programs by responsible breeders. Tests that are available now are x-rays to detect displaced or malformed hips, elbows, and knees; eye tests for progressive retinal atrophy; a biopsy for sebaceous adenitis; a blood test for hypothyrodism and vonWillebrand’s disease (a bleeding disorder); the BAER(1) test for deafness; and a smattering of other tests that aid in detecting breed-specific diseases.

Responsible breeders take advantage of these tests and plan breedings accordingly. Here’s how our round table participants deal with genetic problems in their breeds.


Gale Snoddy, Borzoi breeder, Milford, Ohio

Genetic screening tests are ONE tool used by breeders to help reduce the incidence of certain problems in a breed. Dogs that show problems can then be eliminated from a breeding program. Removing these dogs from a program will REDUCE the occurrence but cannot eliminate it. Testing will not identify carriers, i.e., dogs that do not have a particular condition, but can still produce it. Additionally, many genetic diseases do not manifest themselves until the dog is older and may have already been bred. Furthermore, there are many genetic diseases or conditions for which no test currently exists, such as torsion (bloat), which can kill a dog in a matter of hours. In the future, researchers will be able to identify the genes that cause many of these problems, and this will be a much greater help to breeders.

Due to the enormous expense involved, breeders usually only test the dogs that are used in a breeding program. The other dogs produced in each breeding are tested only if symptoms warrant. It is incumbent on all breeders, and anyone who buys a dog from a reliable breeder, to be honest and open about any problems they experience. By judiciously sharing information, screening for genetic diseases, carefully researching the background of all dogs incorporated into a program, a breeder can make significant strides to eliminating problems from their dogs.

There are a couple of different organizations that provide certifications for the areas being tested. There is a fee involved above the veterinariary charges for doing the test. My main reason for doing the exams is to know my dogs do not have any problems, not to receive the certificates back from the agencies.

Eye exams (CERF)(2): Borzoi do experience various eye problems, most notably PRA. Years ago this was a significant problem in the breed. Today, through eye checks and careful breeding, the occurrence is small. Eye exams need to be done yearly, and many diseases do not manifest themselves until the dog is older.

Thyroid (OFA)(3) Hypothyroid (underactive thyroid) is not uncommon in Borzoi. Hypothyroidism causes poor coat, weight gain, conception problems, lethargy, grumpiness. Left untreated, more serious neurologic and muscular problems can result. It is easily treated with daily medication, but dogs who have this condition should not be bred. Tests should be done yearly, and dogs don’t usually experience problems until they are older.

Heart (OFA): Borzoi do experience various heart diseases. Cardiomyopathy, an enlargement of the heart which is fatal over time, is perhaps the most common. (Medication can extend the lifespan.) Unfortunately, this does not often occur until the dog is older. To complicate the issue, cardiomyopathy can also be caused by infections.

Other heart diseases, such as TVD (tricuspid valve dysplasia) are present at birth, although outwardly the puppy may appear normal in all ways. TVD is often fatal at a young age, and there is often a high whelp mortality in litters of bitches who are carriers. There is no treatment.

Heart exams should be done every one to two years.

Hips and elbows (OFA or PENN-HIP(4)): Borzoi have the next to lowest occurrence of hip dysplasia in all breeds. (Recently released OFA figures show only 1.8 percent of Borzoi affected.) Because of this, I have not personally done these exams on any of my dogs, although I do plan to do some of my youngsters this fall.

Hips and elbows are done once, after the age of two years. A panel of three vets reads the x-rays and grades them. However, there are a few known test cases where x-rays were relabeled and re-submitted and a different rating was received.


Paula Drake, Akita breeder, Cincinnati, Ohio

Just like humans tend to inherit traits from their ancestors, so do dogs. In humans, inherited genes influence not only physical build, eye color, and skin color, but also a long list of attributes like artistic ability, musicality, mathematical prowess, and athletic ability.

Our inherited genes also may predispose us to a variety of health concerns like diabetes, cardiac conditions, cystic fibrosis and cancer.

In dogs, scientific screening tests help us identify a number of genetic diseases. Certain breeds may be more predisposed to produce certain health problems. For my breed, I screen for hip dysplasia, thyroid imbalances, and eye problems.

Additional screening takes place also. Some diseases, like VKH (an eye disease that causes blindness), sebaceous adenitis (a skin disease), and cancers, cannot be screened by blood work or x-ray. A responsible breeder culls any dog from the breeding program who develops or produces a known hereditary condition which impacts the dog’s ability to live a long healthy happy life.

As a dog breeder, it is my responsibility to identify as many inherited positives and negatives as possible, so that when I plan a breeding I am strengthening my breeding program, much like animals in the wild where, in order to assure survival of the species, only the strongest breed.

When I sell a puppy, I must be able to say that I have done everything I can to produce a healthy dog. I want my dogs to live long happy healthy lives. I want the owners to know the puppy they are purchasing comes from a breeding program where health, longevity, and temperament drive the effort.

It is not enough to breed cute pretty dogs. Genetic screening helps produce healthy dogs.


Melody Greba, German Shepherd Dog breeder, Verona, Kentucky

We hip certify all of our breeding stock and on occasion, certify elbows. Elbow dysplasia had not been a big problem in the past for the German Shepherd Dog, but it seems to be slowly increasing in some lines.

We screen our dogs through the Orthopedic Foundation for Animals. Hip dysplasia is a polygenic disorder: groups of genes contribute to this problem, not just one particular gene. With consistent testing of both parents, grandparents, etc. this abnormality can be managed.

Dogs bred without regards to passing hip certifications, have a much higher propensity on reproducing the problem. Dogs with severe hip dysplasia, may show deterioration as young as age of six mos. Total hip replacement surgery for this defect is generally $1500 per hip. It is the responsibility of anyone breeding German Shepherds to hip certify their breeding stock.


Tracy Leonard DVM, Basenji breeder, Dayton, Ohio

For my Basenjis, I screen hips, eyes and urine. At two years of age, I do an OFA X-ray of my up-and-coming stock. It is a one time screening. Eyes are screened yearly. My breed has PRA (progressive retinal atrophy) and it seems to be a late onset disease. Hopefully, we will one day be able to have genetic/DNA testing for it like some other breeds. Fanconi syndrome, a type of kidney failure, is also a problem in my breed. It is detected by finding glucose in the urine. I test monthly for it by a simple urine stick test that is often used in managing diabetes. It is also a late onset disease.

Why bother? Because I want to have the healthiest puppies possible. I breed first for myself and, like I always tell my puppy buyers, I have great leftovers!


Notes

1. BAER is the Brain Stem Auditory Evoked Response test given to puppies to determine if they are deaf. It is used by breeders of Dalmatians, Bull Terriers, Boston Terriers, Australian Shepherds and other breeds in which deafness can be a problem.

2. CERF is the Canine Eye Registry Foundation, a nonprofit organization that evaluates eyes for signs of disease and certifies dogs free of abnormalities.

3. OFA is the Orthopedic Foundation for Animals, a nonprofit organization that assesses hip and elbow x-rays and thyroid tests to determine if dogs are affected by inherited abnormalities. Dogs that are clear are registered.

4. Penn-HIP is a hip evaluation service that uses a different scale to analyze hip health.

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