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04 Eliminating JRD




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This article is from the Juvenile Renal Disease, by Susan L. Fleisher

04 Eliminating JRD

Among the pedigrees I have collected are those of twenty five litters
of an American Champion sire. There are a large number of American
Champions among his offspring. In two of these litters there was one
puppy with JRD. The sire is therefore a carrier, and half of the
puppies in every one of his litters are carriers. This is just one
sire: the arithmetic is stunning. The possibility that this will not
eventually touch every breeder in the breeds in which it is known is
unlikely, and, by the time it does, it will be difficult if not
impossible to eliminate.

In order for Juvenile Renal Disease, sometimes called Familial Renal
Disease, Renal Dysplasia, or Congenital Hypoplasia to be studied in
any breed, several things have to occur. Breeders of breeds affected
by this disease should have any stillborn pups and all pups who die
before being sold, autopsied, if only to look for this one disease. If
the puppy is seen to have JRD, (the kidney cells actually have to be
studied under a microscope, since occasionally the kidneys appear
normal to the naked eye), the rest of the litter can be tested.
Bloodwork should be done to look for an elevated BUN, and urine tested
to establish a urine protein creatinine ratio. Unaffected litter mates
should all be considered carriers, since there is no way to
distinguish a carrier from a non carrier puppy. The only positive
outcome of having an affected litter that I can think of is that it
enables the breeder to identify carriers and potential carriers. Every
affected litter has the potential to stop carriers from producing more
carriers. If an autopsy shows that a puppy did not die of JRD, that is
also useful information. I realize that post mortem examinations are
expensive, though a restricted exam to look for one specific finding
would be much less expensive. I can assure anyone that is infinitely
more expensive on an emotional as well as a financial basis not to
have an autopsy done to look for this disease. Once carriers and dogs
who are clear have been identified, concerned and careful breeders can
work to systematically breed the disease out.

George Lees, DVM of Texas A & M University is currently doing
reasearch on Juvenile Renal Disease in Cocker Spaniels. The Soft
Coated Wheaten Terrier Club of America is sponsoring research by Dr.
Shelley Vaden at the North Carolina State University College of
Veterinary Medicine. Dr Vaden is collecting health records on SCWT,
and she has established a breeding colony.

The Department of Human Genetics at Michigan State University has a
large grant to be used in gene marker research. The initial effort
will be to develop 400 DNA probes in order to saturate the dogs'
chromosomes with the probes. After the probes have been established,
screening can begin for linkage of any dog disease gene of interest.
Eventually, the benefits will be that dogs will be able to be screened
for the carrier state of the gene. This research will not be completed
for many years. In the meantime, since the funding is sufficient only
to develop the probe system and not to study any particular disease,
funding will have to be provider by breeders themselves or by other
outside sources for the study of specific disease gene projects. For
the first few individual studies, the estimate is that the cost will
run from $25,000 to $50,000 to screen through the 400 probes to
establish a close linkage. In order to carry out screening for linkage
for this or any other genetic disease, pedigrees of 15-20 litters in
which there are at least two affected and two unaffected puppies must
be identified. Blood samples from at least two affected puppies and
two unaffected puppies in each litter, as well as from both parents
have to be available for study. Puppies from a repeat breeding are
considered littermates for this purpose. The blood samples can, of
course, be stored for future use. Several other universities, such as
Texas A & M and the University of California at Berkeley are involved
in DNA research also.

Waiting for DNA testing to become readily available is not a feasible
solution to the problems of genetic diseases. Selectively breeding
away from carriers now is the only responsible action. In some
instances, careful breeders have succeeded in largely eradicating some
genetic disorders from their breeds. Success depends on a number of
factors. Every puppy buyer must be encouraged to report any major
illness back to the breeder. Breeders must have a clear understanding
of the modes of transmission of genetic disorders that affect their
breeds. Known carriers as well as possible carriers, (littermates and
offspring of those discovered to be carriers) must be conscientiously
kept out of the gene pool. A method of communication among breeders
must be established. Clearly, an open registry such as the open
registry begun in July, l992 for Sebaceous Adenitis in Standard
Poodles (this disease also occurs in other breeds) is an important
step forward and an invaluable resource. Registries in many canine
diseases are being established at the GDC (Genetic Disease Control) in
Davis, California. In Europe, open registries have made it possible
for careful breeders to greatly reduce the number of cases of some
genetic disorders.

An open registry would include the names of carriers of the disease as
well as the names of dogs who are clear, those who when bred to a
carrier did not produce any cases of the disease in a litter of
significant size. Obviously, the early onset of Juvenile Renal Disease
allows carriers to be identified much sooner than does a disease which
manifests itself later in life.

Malcolm B. Willis wrote in his introduction to Genetics of The Dog,
"We are the custodians of our chosen breeds during the relatively
short period of our dog breeding lives. It behoves us to hand over the
material we breed with in a better state than when we received it or
we have achieved nothing and the breeds we profess to love will be the
sufferers."


 

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