The Maine coon cat is a healthy cat in general, but as in other cat breeds, there are some genetic diseases that we should be aware of.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy, HCM, is a heart disease that occurs in several cat breeds, including Maine coon. It manifests itself by thickening the walls of the heart, causing difficulties for the blood to pass through the heart.  By ultrasound examination, the disease can be detected, but there is, unfortunately, no cure. The cat dies sooner or later of heart failure or blood clot.

Since the disease is progressive, it often develops when the cat is a few years old. Usually, HCM is detected in a cat at 2-3 years of age, but it may take longer before the disease occurs. This is why it’s so important to remember that a heart test when the cat is very young does not guarantee anything, the cat can develop the disease later. I often see cats with only one HCM-test at about 1 year of age.

How the disease is inherited is not discovered yet. Some science shows that it has to do with a dominant gene with incomplete penetrance. If this is true future science will tell.

By doing regular ultrasound examinations on the cats in the breeding stock, we reduce the risk that the predisposition for HCM will continue down the generations. Since January 2004 Maine Coon-katten runs the Health program against HCM. (Since a couple of years back Pawpeds runs all the administrative tasks).

More to read about HCM, click here!


Hip dysplasia

If you own a dog you probably recognize the designation HD – Hip Dysplasia.

This genetic defect is present even in cats. Maine Coon breeders all over the world have since many years back found HD in the breed and take action to minimize the presence of the disease.

Normals Hips 

Hips with degree 3 – Severe HD 


HD means a defect on the hips so that the hip bullet does not fit right into the hip socket. On the picture to the right, the hip bullets are almost completely outside the hip sockets, which is very shallow. This is the most severe degree of HD. Cats with mild HD can live without having any problems, while severe HD could mean difficulties for the cat to move around and also pain and inflammations in the joint. It is possible to operate a cat who has a lot of problems with their HD and the result is almost always good. HD is graded on a scale from Normal to degree 3 (Severe HD).
Breeding on degree 1 is ok as long as the other party has Normal on both hips.

In January 2000 the Swedish breed association Maine Coon-katten started a register for HD to mapping the presence of HD. Responsible breeders x-ray there cats earliest at 10 months of age, but before first mating and send the x-rays to Per Eksell for examination. Per is a specialist in the area. Per then sends in the results to the HD-register.

Read more about the Health program against HD here.

Results and statistics from the healthprogram is published regularly. Below is some examples from the register (2012): 

Cats Tested: 2988

Offsprings from parents, both with unknown hipstatus:

Offsprings from parents, both with known normal hipstatus:

Normal:    1902 (63.7%)

Borderline:  127 (4.3%)

Degree 1:     571 (19.1%) 

Degree 2:     295 (9.9%)

Degree 3:      93 (3.1%)

Normal:     650 (58.9%)

Borderline:   43 (3.9%) 

Degree 1:     221 (20.0%)

Degree 2:     139 (12.6%)

Degree 3:      50 (4.5%)

Normal:     454 (76.0%)

Borderline:   22 (3.7%)

Degree 1:      82 (13.7%)

Degree 2:      32 (5.4%)

Degree 3:       7 (1.2%)

(Earlier we did had borderline, this one is now longer used).

New statistics from 2019 on the bottom you can see the parent's results and the stack in the diagram is the results of the offsprings.
As you can see if you mate Normal-Normal about 70% become normal you got about 20% having an old degree borderline or degree 1 and only about 10% got degrees 2 or 3. While if you look at the stack where the parents are of unknown status, somewhere around 55-58% become Normal while about 25-28% something got old degree Borderline or degree one and almost 20% got degree 2 or 3. 


HD is as far as we know inherited recessive, polygenetic. This means two cats with normal hips can get an offspring with HD and the other way around two cats with HD actually could have got an offspring with normal hips. It is therefore important to do the x-ray on every generation to minimize the risk of HD. In the dog-breeding society this selective breeding has led to a drastic dip in the presence of HD.


Click here to read about PK


Click here to read about SMA


There are three blood types in cats A, B and AB. The most common blood type is A, which is dominant and is present in all breeds. Bloodtype B is relatively common in some breeds.


Do we really need to blood type our Maine Coons?  A couple of years ago I would have said no, absolutely not, there is no point in doing that. BUT then the thing is it has started to appear B-type carriers as it seems recently a lot of them. Apparently some study on Turkish Van says that it is better to have some b-carriers then only A for some reason.

To get a B-blood female is pretty hard so personally, my opinion is to try to avoid this to happen.

Blood type A, B, AB and also A(b) by DNA will be able to add to PawPed.  To avoid misunderstandings regarding the results from the blood test (serological test) versus DNA-test the international alternatives below have been added to Pawpeds.


N/N (not a carrier of blood-group B) 

A/A not a carrier of blood-group B 

N/b (carrier of blood-group B) 

A/b carrier of blood-group B 

b/b (homozygous for blood-group B) the cat has blood-type B

N = Normal


Statistics from 2010:

Type B

Type AB

Total tested

Maine Coon





Statistics from 2018 (Cats tested with MyCatDNA):

Type B

Type N/b or  A/b

Total  tested

Maine Coon




(These statistics were collected before I tested my female who is actually b-blood so the Type B is no longer completely 0%)

By: Malin Sundqvist
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