"I never heard of a cat that suffered from insomnia." -- Joseph Wood Krutch
All pedigree breeds have their problems, and Maine Coons are no exception. While the majority of Maine Coons are healthy and can be expected to live a normal pedigree lifespan of around 15 years, there are two hereditary conditions which can affect them - a heart condition known as hypertrophic cardiomyopathy (HCM for short) and hip dysplasia (sometimes shortened to HD).
HCM (Hypertrophic Cardiomyopathy)
HCM is a slowly developing heart condition which results in a thickened heart wall (so the heart cannot pump as effectively), and enlarged papillary muscles (which has the same effect). It usually shortens life, but has variable effects - some cats can live a long time with this illness, others may die very young. It progresses more rapidly in some cats than others.
HCM in young to middle aged cats is genetically caused. We now know that more than one gene can cause HCM in Maine Coons. The genes involved are dominant, which means that one parent must be affected in order to pass it on (it cannot be carried in a hidden manner). However because it is a slow developing disease it may not be obvious that a parent is affected until after they have had kittens (perhaps many kittens). HCM can be detected by a cardiac ultrasound, but this only tells us that it is or is not present at the time of testing, so it can still show up at a later age. The lowest risk cats are those that have parents or grandparents with no sign of HCM when middle aged or older - so one of the best precautions is to make sure all ex-breeding cats continue to get tested to at least age 8.
There is a genetic test for one of the genes that plays a part in causing HCM in Maine Coons - the MyBPC mutation. However as breeders have begun testing it has become clear that many Maine Coons with only one copy of this gene are symptom free well into middle age. There must be other, as yet unidentified factors that affect the progress and severity of the disease. Nevertheless, removing this gene from breeding populations will help to reduce the incidence of HCM in Maine Coons.
All of our breeding cats are scanned regularly during their breeding careers for HCM and all are negative for the MyBPC mutation.
Hip Dysplasia
It appears that hip dysplasia (as seen on X-ray) is fairly prevalent in Maine Coons. Hip dysplasia is a condition where the hip joint does not fit well into the hip socket. Over time the joint is damaged by the knocking of the head of the femur against the socket. Arthritis may set in, and in moderate to severe cases the cat may develop painful symptoms and lameness. For those cats who are affected it can have a dramatic effect on their quality of life. However, in cats, mild hip dysplasia that is seen on X-ray, usually does not cause overt symptoms. Moderately affected cats will develop stiffness and discomfort - supplements and/or special food, and injections of Cartrophen can often help. Severely affected cats often need surgery that removes the head of the femur - this is quite expensive and is major surgery, however it is usually very effective.
The mode of inheritance of hip dysplasia is thought to be polygenetic (that is, it is caused by a group of genes working together). Our best bet is use only those cats who have no signs of HD at all. However with a prevalence of 50% in MCs, we could risk losing too much of our genepool at once, so breeders may choose to use mildly affected cats (HD1) and breed them to unaffected cats.
We screen all breeding cats for HD from 1-2 years and follow the results of parents and grandparents into adulthood and older age.
