Research shows that HCM is inherited autosomal dominant with
incomplete penetration and with variable expression in the Maine Coon
breed. This means that the gene not always shows and that it varies depending
on how early the disease occurs and how severe the disease gets despite
of the fact that it is dominant. It is estimated that 10-15% of the Maine
Coons have HCM.
As HCM is a so called progressive disease, which means that it developes
gradually during the years, it is considered to be more difficult to fight
in comparison to other diseases. The Swedish Maine Coon Cat Club has worked
out a health programme which will advise breeders to carefully select
their breeding stock in order to minimise the quantity of affected cats
in the breed in future.
Recommendations for testing:
The first HCM test should be done at the age of 1 and before the cat
is used in a breeding programme. Further tests are recommended at 3 years
of age. After that testing is recommended at the age of 5. When it comes
to rexes which have become very important for the general breeding stock
or who are in an especially risky position (equivocal test result or having
a close relative who has been diagnosed with HCM) it would be wise to
do a test at 2 years of age and later as well, for example at the age
of 8. Please observe that this is just a general point of view which has
to be interpreted in each specific case individually.
Recommendations for breeding:
Also here the recommendations are a general point of view where you
have to look at each specific case individually.
*) Close relatives here means brothers and sisters, parents and their
offspring.
Normal heart:
Cats with a normal heart status according to a test and without any close
relatives* diagnosed with HCM can of course be used in breeding from a
HCM point of view.
Diagnosed with HCM:
Cats diagnosed with HCM of any degree should not be used in breeding.
Cats with equivocal test results
Equivocal means that there was something found in the heart during the
HCM test that is not 'normal', but at the time of the test it is not clear
whether it is HCM or whether it could develop into HCM or not.... It does
not automatically mean the cat will develop HCM!!!! Equivocal means exactly
equivocal. The anomaly could be caused by other things like high blood
pressure, kidney insufficiency, or something else. The cat could also
have a normal variation on the 'standard' values, like e.g. the papillary
muscles could be a bit larger than those of the average cat; only further
tests will show if this is HCM or not.
Cats who have got an equivocal test result should be handled as follows:
Equivocal, younger than 2 years:
If the cat was younger than 2 years of age when the test was done it is
not recommended to use this cat as far as breeding is concerned. Instead
another test is done when the cat is older than 2 years.
Equivocal, 2-3 years:
If the cat was between 2-3 years of age when the test was done one litter
can be planned if absolutely necessary, if the cat does not have any offspring
earlier. The other parent should of course have a normal heart and not
have any close relatives* who have been diagnosed with HCM. These kittens
are not allowed to be used in a breeding programme for the time being.
This ban on not using these kittens for breeding can be withdrawn if the
parent of high risk has a normal heart or is still equivocal at a another
test at the age of 3.
Equivocal, older than 3 years:
If the cat was older than 3 years when the test was done the cat can be
used in a breeding programme but must only be mated to a Maine Coon with
a normal heart and who has no close relatives* diagnosed with HCM.
Close relatives of affected cats
If a cat is diagnosed with HCM the following is recommended for its
close relatives*:
Close relative has been diagnosed with HCM, the heart is normal on the
cat itself when the cat is younger than 2 years:
These cats are not recommended to be used in a breeding programme until
it has been approved for breeding after another test at the age of 2.
Close relative has been diagnosed with HCM, the heart is normal on the
cat itself at the age of 2-3 years:
One litter at the most is here recommended if the cat has no offspring
earlier. The other parent should then have a normal heart and have no
close relatives* diagnosed with HCM. The kittens in this litter is not
to be recommended for breeding for the time being. These non breeding
recommendations can be withdrawn if the parent of high risk still is showing
no sign of HCM at the age of 3.
Close relative has been diagnosed with HCM, the heart is normal on the
cat itself when the cat is older than 3 years:
If the cat still has shown no sign of HCM at the age of 3 the cat can
be used in a breeding programme. It should however preferably be mated
to a Maine Coon which is a risk free partner (not equivocal or cat with
a close relative* diagnosed with HCM).
If the cat has been diagnosed with an equivocal heart and also has a close
relative being diagnosed with HCM you should be extra cautious.
Help!
If you feel unsure about what applies for your cat, please don't hesitate
to contact the contact person, Marie Wickman, giggle-s@telia.com
for the health programme!
|