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"Hypertrophic cardiomyopathy (HCM) is the most common form of
heart disease in the cat. In many breeds it is an inherited disease."
Washington State University Veterinary Cardiac Genetics Laboratory
1. Why was the HCM pedigree survey performed?
We began to hear of HCM cases in the Siberian cat, and research
veterinarians had determined HCM was primarily a genetic
disease. The gene responsible was thought to be dominant
with incomplete penetrance, which means that not every cat
with the gene will show symptoms. We felt that by studying
pedigrees it might be possible to discover the ancestry of Siberian
HCM.
2. How was the pedigree survey performed?
We gathered names of Siberian cats that were publicly registered
as HCM positive and reviewed the pedigrees for common ancestors.
We also contacted owners and breeders and asked for their cooperation.
Each was asked to specify whether the name of the cat could be made
public or maintained confidential. When our survey was publicly
announced to the Siberian community, more cases came forward.
3. How did you find and verify the pedigrees of these cats?
In most cases, breeders or owners sent certified pedigrees for us to use.
We cross-checked these with both Pawpeds.com
and private databases where possible. In the process we found some pedigrees
were incorrect and a few cats had multiple pedigrees.
4. Why include cats where pedigree might not be accurate?
Cats were included in the survey if they had HCM verified by
veterinarian diagnosis. While an incorrect pedigree calls the ancestry
into question, it certainly does not change the diagnosis, or the
potential for descendents to express the disease. In one
specific case of questionable heritage, multiple cats have
contracted HCM. Including these cats will help researchers
in their study to isolate specific genes.
5. If my cat is related to an HCM positive cat, does my cat carry HCM?
There is no way to be certain at this time. Researchers need
to isolate the genes responsible for Siberian HCM and develop
genetic tests. We encourage breeders to obtain an echocardiogram
of breeding cats at the age of 3 yrs. This is especially important
if a family history of heart disease exists or sudden death occurs
from an unknown cause in a close relative.
6. Why is HCM talked about now, but I rarely heard about it 7 years ago?
Only recently was it apparent that HCM was hereditary, and more
owners are having their cats checked. Necropsies (cat autopsies)
are performed now when the cause of death is unclear.
Breeders are beginning to be open about deaths from HCM
in their catteries.
7. Why are some breeders not open about HCM in their catteries,
and why did some request their records be kept confidential?
Many breeders believe they will be blamed for selling kittens
that develop HCM, and are concerned about negative publicity.
The Siberian community is small. Some breeders simply do not want
their breeding choices scrutinized by others.
8. Have you identified the ancestor(s) who caused HCM in the
Siberian breed? Yes, we have general indications
that do point to specific different points where HCM entered
the Siberian breed. Using pedigree analysis to
pinpoint ancestries is only as accurate as the pedigrees
involved.
9. Is Dr Meurs, who discovered HCM in
Maine Coons, involved?
Dr. Lyons and Dr. Meurs will be working together
on this project. The search for Siberian HCM genes may take
several years, as we expect there to be multiple genetic
variations
involved.
10. What can a responsible breeder do about HCM?
Study how to manage HCM in a breeding situation. Starting at
3 yrs of age, have your cats thoroughly examined for HCM
every two years. Post results on your website. Encourage other
breeders to have their cats checked. Before purchasing new
breeding cats, ask to see test results of the parents and
ask about family history of heart disease. If your cats dies suddenly without cause,
consider a full necropsy. Follow-up with owners
of kittens you have placed and ask about health issues.
11. Why won't you post your conclusions openly?
From the start, we emphasized that we were not trying to
place blame, but rather understand the spread of the disease.
Some breeders were in a vulnerable position, and
others felt there would be snap judgments. While we do have information that indicates specific ancestries of HCM
in the breed, it may be premature to make blanket judgments.
12. How can we benefit from your work?
Study articles on
HCM. Understand that HCM can be genetically present, but
the cat may never show symptoms in its lifetime. This same
cat can transmit the HCM gene to its descendents. This
is why the disease seems to skip generations and then reappear.
Review open HCM records and compare the pedigrees. If you are
concerned about a sire or dam's ancestry, consider
selecting breeding animals from different lines. If an
ancestor carried HCM, it does not mean that all the
offspring are affected. We must wait for a genetic
test to be certain about a specific cat. An excellent article
"Feline Hypertrophic Cardiomyopathy: Advice for Breeders"
is available. Dr Meurs' DVD on HCM also gives her latest
information regarding helper genes that can cause HCM to appear
or be accelerated.
13. What do you think about the HCM map by Magny Eggestadt?
The map demonstrating potential lines of HCM, and recently
published by Magny Eggestadt is an outstanding work. She used
open-source data from PawPeds and SäSK only, and her research
was fully independent of ours. Only through this type of work
will we understand possible paths that HCM has taken through
Siberians. We would encourage breeders to look at this resource
in their study of HCM.
14. What another map from Onix Gloria?
We applaud Onix Gloria for acknowledging the problem of HCM
in the breed. Tatyana Alekseeva suggested that there may be
incomplete or incorrect pedigrees in Pawpeds and in formal
pedigrees which have led to incorrect conclusions.
We encourage her and the Moscow club to submit corrections.
We studied her map and were able to merge it with a majority
of the Moscow HCM cases. We did note that the theory of helper
genes however is strongly validated when the two maps are meshed.
15 Are you available for consultation on HCM?
Yes, all SRI members may request consultation regarding
pedigrees and potential genetic issues. We are not
experts on HCM or genetics, but put hundreds of hours into
study of the disease and its progression in Siberians. It
was slow and difficult to educate ourselves on such a
complex issue. We also encourage breeders to learn about
HCM and carefully study the lines involved.
16. Is there good news here now that I am worried?
Yes, definitely. Siberians are basically a healthy breed with less
hereditary diseases than many other breeds. Our goal was to provide
a basis for sound research that could slow the spread of HCM in
Siberians. We have identified over eighty HCM positive Siberians
and carefully mapped the lines involved. In addition to the cats
in our study, we know other breeders sent data directly to Dr Lyons
and Dr Meurs. Each additional case will help speed up progress.
We encourage breeders to submit positive HCM cases to Dr. Meurs.
17. Do you accept donations for HCM research?
No, we are a non-profit organization set up for research and education
only. Donations for studying Siberian HCM should be made to
Siberian Research FundRaising
This site sends all money directly to Dr Meurs or Winn
Feline Foundation for Siberian HCM genetic studies.
Siberian Research Fund Raising is not affiliated with SRI,
but we strongly support their efforts!
18. Is the Siberian HCM gene the same as identified
in the Maine Coon?
It is unlikely, but the samples will be reviewed at Dr.
Meurs lab. We have tested three HCM positive Siberians for the Maine Coon gene
and the results were
negative. Four
mutations are thought to exist in the Maine Coon breed alone.
We expect to
see multiple types in Siberians also.
19. Why are records in your survey
not registered on PawPeds as HCM positive?
At this time, Pawpeds publishes only reports from
veterinarians that already participate in their certification program.
Unfortunately, few cardiologists are certified
and these only in Europe. Our records are verified reports from
veterinarians and cardiologists, and clearly state the level of
documentation.
20. Will you post open-release records of Siberians with HCM?
It seems appropriate to those concerned about the health of the
Siberian that we release non-confidential information.
We will release cases where the breeder has permitted public release of the cat's health for the benefit
of the Siberian community. This information is shared for
factual reasons, and should not be used to criticize the
breeder.
21. What are you doing about HCM now?
We feel that our primary goals have been achieved, and wish
to provide breeders what support and information we can.
We also continue to work with Dr. Meurs and Dr. Lyons as
needed for their research.
Portions of this article were originally published in the
Taiga Siberian Breed Club newsletter, March 2007.
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