Above is Sunstorm, my first Maine coon. She lived to be 15 years young.
(always an indoor cat, this photo was edited to look as if outside)
To the right is Cumbrescoons Chip, still in a very special & loving pet home. He turned 15 on February 16th, 2019
HCM (hypertrophic-cardiomyopathy INFO
Maine Coons are a hardy, “working” breed. These cats developed in New England, They evolved naturally, with adaptations for the cold climate. The strongest cats survived to pass their genes down the line to the Maine Coons we have today through natural selection.
However, when man interferes with nature in the ongoing effort to “improve the breed”, which we have so often done with many of the "purebred" creatures, this process has at times led to the over-dependence on some gene pools that had developed health issues that, unfortunately, breeders weren't aware of at that time. Some of these issues are what we know today as "genetic" (passed from one generation to another through DNA.)
Very few of these conditions are breed specific or even limited to one species, although some are more likely to present themselves in specific "types" of animals.
Many people looking for a Maine Coon Kitten or Cat have heard that Maine Coons have a problem with an enlargement of the heart muscle, called “HCM”. In actual fact, this form of heart disease is found in all cats as well as many other species.
In HCM, the muscle of the left ventricle of the heart becomes thickened. There are other changes, but this is predominant. The heart can no longer beat effectively. This can lead to a progressive weakening of the heart, or a sudden death thought to occur from abnormal electrical activity within the heart muscle.
Blood clots can form and circulate to a point where a clot may cause sudden paralysis (often of the cat's hind legs). This serious condition tends to develop in the earlier years, where it affects cats often before they reach 5 years of age. It can show up in older cats as well.
With humans, who can also have an inherited form of this disease, there are many known genetic mutations.
Thus far, research has found one mutation in the Maine Coon breed. Another mutation has been found in the Ragdoll breed. Research into other breeds is ongoing, as is the research to find any other possible genetic mutations in addition to those already identified.
No breeder can say with certainty that, using the technology currently available, that their cats will never develop HCM.
Outside of genetics, other possible causes of an enlarging heart muscle in cats include high blood pressure and hyperthyroidism.
The HCM associated with causes such as these is considered “secondary” HCM. Therefore, it is important to realize that relying on the DNA testing results actually provides no guarantee that any kitten or cat will not develop HCM.
However, DNA testing remains a very useful tool to breeders and pet owners alike. Breeding plans can be developed to avoid breeding two Homozygous cats together and thereby minimizing the risk of kittens developing this serious condition.
Another tool which can be used to diagnose HCM is echocardiography, an ultrasound of the heart. This test must be done at regular intervals to monitor changes within the heart.