Animalia Life

The Breed History
A hardy hunter, this is the only North American longhair cat. Originating in Maine, this breed is now designated as the State Cat of Maine. Perhaps resulting from crosses between domestic cats and Angora and other longhaired imported cats, their large size and a luxurious haircoat are breed hallmarks. It is possible that Pilgrims brought longhaired cats with them that were the progenitor cats, and natural selection resulting from harsh winters favored a long dense coat. Some also credit the origins of the coat type to outcrossing with imported longhaired Siberian Forest Cats or Norwegian Forest Cats. A valued working farm cat, the Maine Coon was used extensively for rodent control. They are one of the first American breeds (first records date to the 1860s), and also one of the largest domestic cats anywhere. Very popular, they usually rank near the top in CFA. Championship status in CFA was awarded in1976. No outcrossing is allowed.

Physical Characteristics
Weight: Range 10-22 lb (4.5-10 kg) Females smaller and more refined than the males.
Coat: Glossy haircoat is longer over the body than on the head and shoulders and longer on stomach and the legs. Ruff is present, especially in males. The Maine Coon is double-coated and fur is thick, shaggy, but soft in texture and waterproof. Most colors and patterns are accepted though brown tabby is the best known. Chocolate, lavender, cinnamon, pointed and agouti are not accepted. Eyes: Eyes are large, and all colors are accepted. Blue and odd eyes are found in the white cats.
Points of Conformation: Powerful musculature characterizes these large cats that are also endowed with a large wedge shaped head. The tapering tail is very long and this thick hairy tail, with rings in tabbies may have given rise to the Coon part of the breed name. The Maine Coon possesses a profile with the medium-length nose that is slightly concave. Well haired ears are large, with pointed tips and lynx tufts. Paws are round and well haired. Tail is long and tapering from a broad base.
Grooming: Though the Maine Coon coat does not tend to mat, regular grooming is needed. Preferably a quick daily session, but many find once weekly brushing will suffice.

Recognized Behavior Issues and Traits
Reported breed characteristics include: Sometimes called the "Gentle Giant" Maine Coon cats are adaptable, and require regular exercise and branches or ledges for climbing and jumping. Playful, and keeping kitten attitude until late in life, these cats like to play fetch. Most will leash train. Agile, powerful, calm, intelligent, good with children and dogs, these cats vocalize with a chirping trill, and the meow is very soft. Some enjoy swimming, and Maine Coon cats enjoy human companionship, and make very good companions. Not considered a lap cat.

Normal Breed Variations They are slow to mature (~3-4 years), and puberty finishes late.
They have excellent tolerance to harsh cold climates.
They normally have have small litters with just two to three kittens but are noted for good mothering.
They tend to gain weight easily.
Blood type B: Prevalence of 3% type B cats was reported.
The long hair phenotype in cats is a recessive characteristic so how it is distributed in the different longhaired breeds, and coded for is of interest. Mutation (AM412646:c.194C>A) is responsible for long hair in Persian and Maine Coon. Mutation 3 AM412646:c.474delT) is only present in Maine Coon cats.

Drug Sensitivities
None reported in the literature

Inherited Diseases
Hypertrophic Cardiomyopathy (HCM): The most common cardiac condition in cats (10% prevalence); in Maine Coon the inheritance is consistent with an autosomal dominant gene with high penetrance. In cats, this heart condition is often associated with arterial systemic thromboembolism and congestive heart failure; specific changes occurring in this breed include papillary muscle hypertrophy, left atrial dilatation, left ventricular wall thickening and mitral valve systolic anterior motion. In cats, pulmonary edema is not necessarily perihilar as in dogs.
Offspring from crossing affected to unaffected cats developed clinical signs between 1-2 years of age, with severe disease by 2-4 years old. If both parents were affected, offspring became symptomatic at about 3 months of age, and severe disease was established by 6-18 months of age. Sudden death and heart failure are terminal sequelae. A sarcomere gene mutation leading to coronary arteriosclerosis and interstitial fibrosis with sarcomere myofibrillar disarray was postulated to be the pathophysiologic mechanism of failure. This condition closely mimics light chain mutations in man.
In man, a number of myosin mutations have been identified, so some HCM cats may be testing negative because their mutation is yet unidentified.
In one earlier report, myomesin (M band sarcomeric protein) was found to be reduced or absent within the myocardium of cats with familial HCM and increased anomalous ОІ-myosin heavy chain protein was also found.4 Affected cats were used to propagate a colony for characterization, and echocardiogram serial studies confirmed 55% of the offspring were affected.
The newest research has now elucidated the genetic defect to be myosin-binding protein C (MYBPC3-A31P). A survey of cats from many geographic areas confirmed the dominant mutation is widespread in the breed, with a worldwide rate of 34%, with 90% being heterozygous.
A prospective ultrasound screening of a group including homozygotes and heterozygotes for the mutation demonstrated regional diastolic dysfunction but left ventricular hypertrophy was also found in wild type cats.
Once severe HCM is established, progression to terminal endpoints occurs within a few months to several years at the most. Typical clinical signs of feline heart disease can be seen but significant disease can be present in the absence of any clinical signs.
Serum cardiac troponin 1 levels (cTnI), a sensitive and specific marker of myocardial damage may be elevated according to early studies and may be useful in future, though further studies are needed. Levels increased to a peak 12-48 hours after an episode of damage, and stayed elevated for 8 days.
Overall, left ventricular outflow obstruction, left ventricular diastolic dysfunction, left ventricular wall (less commonly asymmetric septal) hypertrophy and interstitial fibrosis and ischemia lead to typical heart failure.
Papillary muscle hypertrophy is another finding.6 Average age of onset is 6-1/2 years, and more cases are seen in males. It has been postulated that growth hormone excess may have a role in some cases. Prognosis for asymptomatic cats is good (5-10 year survival), poor for those with arterial thromboembolism (6 months) and moderate survival time of 18 months is typical (with appropriate management) for heart failure.
Report recommendations include: investigate all murmurs in kittens over four months old, screen breeding stock annually during their breeding career using auscultation and echocardiography starting at age 2 for males, and 3 for females; ECG, thoracic radiographs and blood pressure determination may also be recommended if signs suggestive of clinical heart disease such as heart murmur are present. It is very important to note disease may be present without a murmur.
If it is suspected that the cat has died of heart disease, it is recommended to conduct a necropsy. Average heart weight at post mortem is 20 g for moderately affected cats, and 30 g for severely affected patients; myofibrillar disarray is a hallmark histologic lesion.
Spinal Muscle Atrophy (SMA): Autosomal recessive genetic disease causing tremor, proximal muscle weakness, and muscle atrophy beginning at ~4 mo of age. Apparent loss of function is rapid initially, but progresses slowly after 7-8 mo of age, and variably disabled cats lived for at least 8 y. Electromyography and microscopic examination of muscle and nerve biopsies are consistent with denervation atrophy as a result of a central lesion. A genetic test is available.

Disease Predispositions
Hip Dysplasia (HD) +/-Patellar Luxation (PL): Hip dysplasia is more common in cats than was previously thought and almost all cats are clinically normal-clinical signs do not correlate with radiographic changes. A few reports suggest a predilection in females in cats, unlike dogs where no sex predilection exists and a polygenic mode of inheritance is proposed.
In one report in a non random group of 78 cats, 45% of Maine Coon cats had PL and 18% had concurrent HD/PL; overall, the pooled group of cats were three times more likely to have these conditions concurrently than either alone.
In a University of Missouri Veterinary Medical Teaching Hospital study, in 684 cats representing 12 breeds and non-registered domestic cats, domestic cats had hip dysplasia prevalence of 5.8%, pooled purebred cats had 12.3% prevalence, and an overall frequency of HD of 6.6% was found in the entire study group. Unlike dogs, minimal remodeling of the femoral neck was noted. Shallow remodeled acetabulum, with the cranio-dorsal acetabular margin most significantly affected was reported as the primary lesion instead in cats. Reported OFA database survey results (1974-1995) for 284 Maine Coon cats between 12 and 23 months of age showed 21% were positive for HD according to OFA protocol standards.
In another non random group of 121 Maine Coon cats, using the Norberg Angle (NA) and Distraction Index (DI) it was determined 50.4% of Maine Coon cats had HD using OFA guidelines, 85% of these cats had bilateral changes; 57% had concurrent degenerative joint disease. Mean DI for affected cats was 0.64, while the mean NA was 80 degrees. The DI in normal cats averaged 0.55, and NA 92 degrees. If these were dogs, the affected cat scores would be typical of dog breeds with high prevalence of HD such as Newfoundland and Saint Bernard.19 It was notable that most cats are clinically normal. Owner complaints may include reduced height of jumping, walking tucked under, and not running as much.
Thought to be a polygenic trait, it is assumed to be moderately to highly heritable. It is not yet known if limited feeding/weight control has a role as in dogs, but larger framed cats more commonly have hip dysplasia. Until further studies are done, it might be prudent to avoid overfeeding young growing cats.
Renal Failure: The renal failure rate for Maine Coon cats was more than double the baseline rate in a study of cats from 23 veterinary colleges from 1980-1990 (189,371 cases from Purdue University Veterinary Medical Database) at an odds ratio for risk of 2.44:1.

Rare and Isolated Reports
Glycogenosis Type IV (GSD IV) Mimicking Disorder: Though GSD IV is a condition of Norwegian Forest cats, a very similar condition has been noted in a report of 7 Maine Coon cats. It was thought to be an autosomal recessive disorder leading to the neuromuscular disease in that small group of cats. Muscle atrophy, gait deficits, rear weakness and reluctance to jump were signs noted by about 4 months of age. Progression to dsyphagia, and rear limb paraplegia occurred over a year. Elevated creatine phosphokinase enzymes and nervous tissue conduction abnormalities were not evident; iodine stain did not reveal abnormal glycogen accumulation but histology of nervous tissue was abnormal.
Flat-chested Kittens: Flat-chested Kittens: Similar to the flat-chested condition in Maine Coon (see Maine Coon Chapter), whereby reduced dorso-ventral chest dimension occurs. This trait is only seen in some lines. (Dr. Solveig Pflueger, Pers. Comm.) Signs may include poor weight gain, exaggerated cranial thoracic vertebral kyphosis, vomiting, dyspnea, cyanosis, exercise intolerance and cough, and a ridge along the costo-chondral junction of the ribs. As kittens mature and the rib cage calcification completes, clinical signs abate in many of those kittens that were less severely affected and thus not euthanized in the neonatal period. Though recognized by breeders, the flat-chested kittens have not been reported in the literature. Generally, it is first noted at 7-10 days of age.
Muscular Dystrophy (laminin О± 2): A case affecting a 12 month-old cat in Belgium was reported in 2003. The kitten had never walked normally subsequent to adoption at 10 weeks old. No relatives were affected so a genetic basis was not identified, though a de novo mutation could have occurred. Generalized muscle atrophy, limited extension and flexion of limb joints, marked CK elevation and weakness were noted. Euthanasia was necessary due to a progressive condition.
Superficial Necrolytic Dermatitis with Hepatopathy: A 5 year-old cat presented with hepatocutaneous syndrome. Pruritis, alopecia, and liver enzyme increases were noted. Mean survival after diagnosis is about 6 weeks in dogs and was similar here; etiology is unknown.
Hereditary Deafness: Is associated with the dominant gene for white cat (W); may be found in white cats of this breed. Brainstem Auditory-evoked Responses (BAER) can be used to evaluate hearing, as in dogs. Hearing loss may be bilateral or unilateral.
Motor Neuron Disease: In a review paper, a juvenile onset MND case was relayed, affecting Maine Coon cats. An autosomal recessive inheritance was postulated. At 4 months of age, onset of severe weakness and muscle atrophy occurred and by late juvenile phase, kittens would walk with a "pelvic limb sway".

Genetic Tests
Hip Radiographs: With OFA testing, 24 months of age is the minimum age for certifying hips but evaluations can be carried out earlier. Note that the Penn Hip system picks up joint laxity (can determine DI). Joint laxity is correlated with DJD. Consider checking patellar luxation propensity by manual palpation, and if positive, take stifle radiographs at the same time. Recommendations given were to recheck breeding cats annually for HD since some may develop radiographic signs only later in life.
Renal Function: Screening for renal function using serum creatinine and urinalysis in cats 8 years or older is recommended since a breed propensity to renal failure was found. Microalbuminuria and Urine P:C ratio may also be used for early screening.
HCM Monitoring: Yearly auscultation by a veterinarian to check for murmurs/arrhythmias is a minimum in normal cats. Breeding cats should be checked annually by echocardiogram since some may develop HCM later in life. Monitor starting at age 2 for males, and 3 for females; ECG, thoracic radiographs and blood pressure determination may also be recommended if signs suggestive of clinical heart disease such as heart murmur/arrhythmia are present.
Normal M-mode echo parameters reported for Maine Coon cats differ somewhat from the typical domestic cat, so these means should be used for reference when screening healthy cats and are provided in this report.
HCM Genetic testing is available at NC State-Meurs Lab.
Direct genetic test for SMA is available from MSU-Fyfe Lab.

Miscellaneous
- Breed name synonyms: Coon Cat, Maine Cat, American Longhair, Forest Cat. (Historical) Maine Shag was used for the cats with colors other than brown tabby.
- Registries: FIFe, TICA, CFA, ACFA, CFF, CCA, NZCF, WCF, ACF, GCCF.
- Breed resources: CFA Maine Coon Cat Breed Council: mainecoonbc.org
Maine Coon Cat Club: maine-coon-cat-club.com/
The Maine Coon Breeders and Fanciers Association: mcbfa.org/
United Maine Coon Cat Association (CFF): cffinc.org/umcca/main.htm
Orthopedic Foundation for Animals (OFA): offa.org