General Description The Maine Coon is a natural breed of amiable character that traces its origin to the working cat found on the farms of Northeast America. The breed of the Maine Coon is large framed with a square outline of the head, large ears, broad chest, solid bone structure, a long, hard muscled, rectangular body and a long flowing tail. Good muscle tone and density give the cat the appearance of power and robustness. Size: large.
Type must always take preference over color. Very slow maturing of the breed should be taken into consideration. Mature males may have larger and broader heads than females. Females are proportionally smaller than males. Allowance must be made for this significant difference in size. Length of coat and density of undercoat vary with the seasons.
Head Medium in size; square outline. Profile with a gentle concave slope. Forehead gently curved. Cheekbones high and prominent. Face and nose of medium length with a square outline of the muzzle. Distinct transition can be felt between muzzle and cheekbones. Firm chin, in vertical alignment with nose and upper lip.
Ears Large, wide at the base. Moderately pointed. Lynx-tufts are desirable. Tufts of hair in the ears extend beyond outer edges of ears. Set high on head with a very slight outward tilt. Ears should be placed with one ear's width apart. The width extends slightly in older cats. Lower base set just slightly further back than upper base.
Eyes Large and widely set. Slightly oval, but not almond shaped, appear round when wide open. Set slightly slanted towards the outer base of the ear. Any color is permitted. There is no relationship between eye- and coat color. Clear eye color is desirable.
Neck Males have a very strong muscled neck.
Body The body should be long, substantial bone structure. Hard muscled, powerful, broad-chested. Large framed, all parts of the body in proportion to create a rectangular appearance.
Legs Substantial, medium length to form a rectangle with the body. Paws should be large, round and well tufted between the toes.
Tail At least as long as the body from shoulder blade to base of tail. Wide at the base tapering to the tip; with full, flowing hair.
Coat All weather coat. Dense. Short on head, shoulders and legs, becoming gradually longer down the back and sides, with long, full shaggy baggy trousers on the hind legs and belly fur. A frill is expected. Texture silky. Coat has distinct body, falling smoothly. The undercoat is soft and fine, covered by the coarse smooth outer coat.
Color All color varieties are permitted, including all color varieties with white; except pointed patterns and chocolate and lilac, cinnamon and fawn. Any amount of white is allowed, i.e. a white blaze, white locket, white chest, white on the belly, white on the paws etc.
Faults Unbalanced proportions. Overall small cat. Round head. Straight or convex profile. Nose break. Pronounced whisker pads. Round or pointed muzzle. Undershot chin. Wide set, flared ears. Slanted, almond shaped eyes. Fine, light bone structure. Short cobby body. Long stilty legs. Short tail. Lack of belly shag. Coat of overall even length. Lack of any undercoat.
The above text is taken directly from the FIFÈ standard for category II - semi-longhair.