Zuli Maluffi
Zuli Maluffi. Photo: Thommy Jacobsson

The health of our cats and kittens is very important to us. Genetic diseases exist among all cats, pedigreed or non-pedigreed. Then different breeds might have different diseases that are more common than the others. To maintain and improve health in the breed and in our cats, we test our breeding cats for the genetic diseases that are the most common in the Maine Coon breed, hypertrophic cardiomyopathy (HCM) and hip dysplasia (HD). We have also tested some of our cats for polycystic kidney disease (PKD).

Hypertrophic Cardiomyopathy (HCM)

HCM is a genetic heart disease that exists in several breeds, as well as in non-pedigree cats. Unfortunately this has become a problem in our breed too. The disease makes the heart grow thicker and thicker until it is no longer capable of pumping the blood in an effective way any longer. Then the cat of course will die. HCM is generally not visible in a kitten. Actually, the disease is usually not discovered at all until the cat suddenly dies. But with an ultrasound test, the disease is detectable earlier. But still usually not in a kitten.

Rani. Photo: Mari Lindqvist

The disease takes longer to develope. In males it is usually possible to detect at 2 years of age, while in females it takes in average longer to develope. In females most cases can be detected at 3 years of age. HCM is, according to American studies, inherited by a single dominant gene with incomplete penetrance. This means that even if only one of the parents carries the gene, the offsprings have a 50% risk of getting it and they can then potentially get the disease. The incomplete penetrance means that not all cats with the gene will actually develop the disease. A few cats simply carry the gene without ever showing any signs of it. But all the cats that carry the gene MIGHT be develope HCM, and most do.

By testing for HCM we reduce the risks of breeding from cats who carry this gene. The tests are not 100% sure though, mainly because of the incomplete penetrance. It is a complicated disease, and more research is needed. But at the moment ultrasound testing is the best tool we have to control it and to reduce the risks.

Read more about HCM at Feline Hypertrophic Cardiomyopathy.

Hip dysplasia (HD)

HD is an inherited malformation of the hip joint, that is less severe cases doesn't cause a cat any problems. In severe cases however the cat might get pain from it and problems to jump and even walk. HD is probably inherited polygenetic, meaning that many genes are involved. This means that breeding for better hips is similar to breeding for large size in the cats. You might get a large cat out of two small parents, but it is less likely than getting a large cat out of two large parents. And sure you might get a small cat out of two large parents, but it is less likely than getting a small cat out of two small parents, or out of one large and one small. In the same way you might get a kitten with severe HD out of two parents with good hips, and you might get a kitten with good hips out of two parents with severe HD. But it is not very likely.

Nanzi's hips
Nanzi. Photo: Falun's Animal Hospital

So what we should do is to breed from the cats with the best hips. We must however be careful not to be too hard here, so that not too few cats are used for breeding. Otherwise our wish to avoid HD might result in a too narrow genepool, leading to inbreeding. And the inbreeding might then cause others and worse problems. Because of this, we have been recommended to for the moment also breed from cats with the mildest degree of HD. Of course we then mate those cats with cats whose hips are good.

We test our cats' hips by x-raying them at the age of 1 year or later. The x-ray pictures then are sent to a specialist in Stockholm, who is judging each hip individually towards a scale ranging from OK hips to grade 3 HD. So grade 1 HD is the mildest grade of HD, grade 2 is moderate, and grade 3 is severe. The Swedish Maine Coon club is then registering the test results in an open registry, starting in January 2000. You can see more hip x-rays in our Hip Reference Page.


Except for testing our breeding cats for genetic diseases, we think that it is very important for the future of the breed to work to maintain and broaden the genepool, to avoid future problems from inbreeding. There are many foundation cats and foundation lines behind the Maine Coons, but through the competition for the best looking cats over the generations some lines have been overused, while some have almost vanished completely. As a result today about 70% of the genepool internationally comes from only five foundation cats! Of course that is too much to come from that few cats. So what we do is to try to reduce the amount of primarily the two most common foundation cats, but also the others, in our pedigrees. This is done both by saving what is still left of other old foundation lines and by introducing newer foundation lines from Maine.

The five most common foundation cats were living in the 1960s' and 1970s', and they are:

  • Andy Katt of Heidi Ho, male, (about 20% of the genepool)
  • Bridget Katt of Heidi Ho, female, (about 20% of the genepool)
  • Dauphin de France of Tati-Tan, male, (about 15% of the genepool)
  • Tatiana of Tati-Tan, female, (about 8% of the genepool)
  • Smokie Joe of Whittemore, male, (about 7% of the genepool)

We usually call these cats the top 5. And we are calculating the amount of them, as one tool of knowing how interesting a pedigree is from an outcross point of view.

The amount of the two most common cats, Andy Katt of Heidi Ho and Bridget Katt of Heidi Ho, we call the percentage of Heidi Ho (or top 2.

Banzai. Photo: Kristina Almkvist

Then we also calculate the amount of clones in the pedigrees. The offsprings of Heidi Ho Sonkey Bill and Tanstaafl Polly Adeline of Heidi Ho were born 1979-1982. They all looked very much the same, and a judge once asked what they did to make them all look so similar. "Do you clone them?", she asked. And since then these brothers and sisters are called "the clones" among the Maine Coon breeders. The clones were very successful at shows, and soon most breeders wanted one or two clones for breeding. Then many inbred on these cats, to get even better looking cats. Today about 35% of the genes in the genepool come from only these brothers and sisters that we call the clones.

Read more about this subject at the Maine Coon Heritage Site.

Our cats' results
HCM echoHCM DNAHDPKD Heidi HoTop 5Clones
RafflanOK 1/07Parents negOK 9/04OK 9/05 25%56%14%
SelmaOK 3/06Neg 5/06OK 4/01OK 3/04 26%62%16%
SossoOK 5/09Parents neg1+1 4/09- 30%63%21%
HenryOK 5/09Neg 6/06OK 3/07Parents OK 21%46%5%
KewaydinOK 5/09NegOK 2/09- 8%16%6%
BroccoOK 5/09Parents negOK 4/09- 30%63%21%
EbbaOK 11/08Parents neg1+OK 11/08- 23%52%10%
MarloOK 11/04Neg 5/06OK+Borderline 6/02OK 6/02 25%50%17%
SoppanOK 3/06Neg 5/06OK 8/00*OK 2/01 6%15%3%
PimOK 11/04-OK 5/99OK 8/99 24%60%16%

*) The result "Good" according to OFA.

Other cats, that may appear in the pedigrees of our litters
HCM echoHCM DNAHDPKD Heidi HoTop 5Clones
Silvermeadow's CassisOK 6/08Parents negOK 3/07Parents OK 32%64%24%
Caprix Blue BogartOK necr 8/08Neg 5/06OK 5/98- 28%53%22%
Prairiebaby River PromiseOK 1/07Neg 10/06OK 6/04OK 6/04 0%0%0%
Fogcity Yankee VikingOK 1/07Neg 5/06OK 6/04OK 6/04 26%58%18%
Ylletrollets LizaOK 11/05Neg 11/06OK 11/05- 27%59%15%
Ylletrollets CissusOK 7/07Parents negOK 7/07Parents OK 26%57%16%
Caprix Creme CaramelOK 12/01Neg 5/06OK 4/96- 27%67%8%
Coonmoonrising BlitzenOK 1/07Neg 4/06OK+Borderline 11/05OK 1/07 33%63%27%
Ylletrollets Lilla ColumbineOK 9/05-OK 9/05OK 9/05 22%52%12%
The Dorsai BanrionEquivocal** 1/03-OK 5/00OK 8/99 14%33%7%
Ruskprickens FidlaOK 1/07Neg 2/07OK 11/05OK 1/07 31%65%20%
The Dorsai BelgarionOK 1/07Het pos 12/061+1 3/04- 31%62%24%
The Dorsai GilgameshOK 1/07-OK 6/04OK 9/05 18%43%7%
Asselies SimiaOK 9/04-OK 7/04- 28%63%16%
Ylletrollets Pongolina OK 6/08-OK 8/99- 24%60%16%
Ylletrollets Paradex OK 8/99-OK 5/98- 22%54%11%
Maffialigan's Kiss Me Kate OK 8/99-2+2 5/98- 17%49%6%
Ylletrollets Bonanzi OK 04-OK 5/98OK 8/99 31%68%21%
Ylletrollets Carananza OK 3/04-OK 1/99- 31%68%21%
Snobbrännans Fanny OK 11/04Neg 10/06OK 1/99- 26%62%11%
Co'Coons Lorelei OK 4/01-OK 1/99- 24%58%11%
Co'Coons Bogilou Bogilei OK 3/04-OK 1/99- 28%63%16%
Ylletrollets Crakatau OK 8/99-OK 11/98- 25%65%7%
Ylletrollets Ina Dexelina --1+1 11/98- 24%60%9%
Heavy Coon's Thunderpaw OK 4/99-1+1 4/99- 25%61%24%
Coonyham Bonanza HCM 5/03-OFA goodOK 1/99 35%68%35%
ARKatz Hondo of Kriscaj OK 2/98-OFA fair- 35%67%27%
The Dorsai Rainbow Warrior HCM 5/01Neg 5/06OFA goodOK 8/99 15%32%6%
Ylletrollets Gräddelinus HCM 5/01-OK 1/00- 25%50%17%
Ylletrollets Krakel Spektakel OK 10/04-Borderline+1 7/01- 26%62%16%

**) Heart was normal later, at a thorough necropsy. The changes in the heart on ultrasound is thought to have been due to her kidneys, which were not well and caused her death. :-(

Welcome | About Us | Kittens | Our Maine Coons | Health | Ylletrolls | Our Turkish Vans | Links | Contact Us
Revised 2009-06-25