Hypertrophic Cardiomyopathy (HCM)
HCM is the most prevalent of heart diseases in domestic cats. It is a heart disease which in a mild case can take the form of a heart murmur, shortness of breath or general malaise. It can also be quite deadly! HCM is a dominant genetic trait which means that if one parent carries the disease, there is a fifty percent chance that any offspring could be effected. Theoretically, it should be possible to completely eradicate the disease. This though is complicated as even though parents are screened, the disease may never show up or not until they are well past breeding age. Screening is done by a specialist using colour doppler echocardiographic equipment to view the heart and the passage of blood through the heart.
Rearch continues to develop a DNA test we hope will help to eliminate HCM from this beautiful breed. In humans there are over 400 genetic mutations which have been indentified in conjunction with HCM. Katherine Meurs of Washington State University has discovered a mutation on the cardiac myosin binding protein (MyBP-C) in Maine Coons. This mutation correlates with a similar mutation in people which causes late onset HCM. Research is ongoing in Maine Coons. To date, over 35% of Maine Coons tested carry this gene but according to statistics, only 3-5% of Maine Coons will go on to develop clinical signs of the disease. Even the genetics are unable to predict the correlation between the test and those cats who will eventually develop clinical signs of HCM.
DNA testing is a tool to be used in conjunction with colour doppler echocardiograph for the testing of breeding cats.
Hip Dysplasia (HD)
HD is another health issue which can sometimes be found in Maine Coons, although this problem does not seem to affect cats to the same degree as it does dogs. Many breeders screen to remove from their breeding program, any cats which show clinical evidence of osteo-arthritic development in the hip joints. The genetic inheritance of this disease is not as straightforward as HCM, and sometime, for all the care that is taken in choosing parents, it can show up in a kitten bred from two parents with apparently perfect hips.
Removal of cats with DJD (Degenerative Joint Disease) from our breeding programs and the use of common sense and good breeding practice is currently the only method available to the breeder to try to reduce the incidence of HD in Maine Coon cats.
HD has been the subject of recent studies by Veterinary specialists. Although there is a reasonably high proportion of cats who fall below the Fair to Excellent range, (as assessed by the Orthopedic Foundation for Animals) it has been shown that only a very small percentage of these cats will develop clinical evidence of the disease.
Polysystic Kidney Disease (PKD)
PKD a disease most prevalent in the persian breed. The Maine Coon as a breed has had very few reported incidences of PKD. In Australia, there were a few cases in cats that had been imported from Europe and are not in breeding programs. However, screening is a simple scan which is done by the radiologist at the same time as the heart screening.
Feline Spinal Muscular Atrophy (SMA)
SMA has not been diagnosed in any Australian Maine Coon that UMCFA is aware of. As all original Maine Coons to Australia have been imported from overseas, we have been lucky enough to have imported from breeders who test and breed from SMA negative cats. As the breed increases in popularity and increasing numbers of breeders are commencing throughout Australia, this status could change with the possible importation of cats who carry this mutation. Please ask your breeder about the SMA background history of their cats.
SMA is a disorder caused by the death of spinal cord neurons that activate skeletal muscles of the trunk and and limbs. This leads to muscle weakness in the first few months of life and atrophy that becomes apparent at 3-4 months of age. Kittens which are affected develop an odd gait with a sway of the hindquarters and stand with the hocks nearly touching. By 5-6 months of age they're too weak in the hindquarters to easily jump on furniture and have clumsy landings.
SMA is inherited as an auosomal recessive trait. A normal cat (geotype N/N) does not carry the mutation and will not develop SMA. A cat with one copy of the gene (N/SMA) is called a carrier (heterozygous) and while it will not develop the disorder, it can pass the mutation onto its offspring therefore should only be mated to clear cats. An affected cat will have two gene copies with the mutation (genotype SMA/SMA - homozygous) and they will always pass the mutated gene onto their offspring therefore should not be used in any breeding program.