HCM (Hypertrophic Cardiomyopathy) is an hereditary heart disease found in almost all breeds of cats including the domestic or moggie. Maine Coon breeders are lucky that heart testing has been commonplace for ethical breeders for many years and so we have a good testing history behind many breeding cats. To evaluate whether a kitten has a good chance of having a good healthy heart, you should take into account the calibre of the person testing the cat, the age of the cat when last tested and the length of time measurements have remained stable. HCM is a progressive disease. A cat can test clear and a year later show signs of the disease. The older a cat is when it is tested clear, the better this is for that cat and its descendents. If a cat is autopsied and shows no histological sign of HCM this means (according to what I have been told) that the cat does not have HCM. A cat can have a clear scan when it is alive, but at the level of the muscle fibres it will show some histological signs if it has a gene for H
Scientists have discovered one gene in the Maine Coon that may lead to HCM (cMyBPC mutation). There are other genes still to be found as there are cats without this gene who have HCM. Work is being done to identify other genes in Maine Coons. Other research is being done to identify the genes that cause HCM in other breeds (Ragdolls, Persians, Norwegian Forest, Siamese, Siberians, Sphynx etc).
To have the best chance of a kitten with a healthy heart long-term you should ensure the kitten does not have the cMyBPC gene and that the parents, grandparents etc have good testing histories. Don't be afraid to ask, and don't be satisfied with vague answers. Ask to see the actual test reports if you are unsure, and don't assume that cats are tested just because their website discusses health testing or even if the breeder says the cat has a good testing history.
Cats in general have mobile, lax joints and many breeds appear to have incidence of hip dysplasia (HD) which can lead to pain, arthritis and limping. Sometimes it can severely affect the cat's mobility. Again Maine Coon breeders are lucky that breeders have had opportunities to have their cat's hips scored over a long period of time. Hip Dysplasia is tricky to eradicate as there are many genes that affect cats' hips. This means that cats with good hips can produce kittens with severe hip dysplasia...and cats with severe hip dysplasia can produce kittens with good hips. Studies have shown that over time the incidence of HD is markedlyzsx reduced if cats with moderate and severe hip dysplasia are removed from breeding.
Hips only need to be checked once, providing the cat is at least a year old.
To get the best chance of having a kitten with good strong hips you should ensure that parents, grandparents etc are free of HD, and there are no cats with severe HD in its history (including other kittens from the parents). Also make sure that the hips have been tested by an expert and not just looked at by a general veterinarian. Hips must be scored by a radiographer with expertise in reading Maine Coon cat hip xrays. Examples are Lars Audell (Pawpeds Hip Program, Sweden), OFA and PennHip (in the USA).
All breeding cats should have their hearts scanned by a veterinary cardiologist
All breeding cats should be clear for the MyBPC gene.
All breeding cats should have their hips tested and have no signs of hip dysplasia
Hearts should be scanned regularly not only once.
A clear heart scan at a young age does not mean the cat is clear of heart problems, as they can develop over time.
The entire pedigree should be looked at before assessing the risk of heart and hip problems. A cat with clear parents may still be carrying genes for problems if there are problems further back in the cat's pedigree.
the more testing there is in the breeding cats background the better and the older the cats are when tested for heart problems the better.