Long Coat, Short Coat, and the One in Between

Coat length in cats is controlled largely by one gene, and long hair is recessive. That single fact explains most of what confuses people about long-haired cats.

Why two shorthaired cats produce longhaired kittens

Because both carried a copy of the long-hair variant without showing it. A cat needs two copies to have long fur, and one copy leaves it short-coated and able to pass the trait on.

The variant is common throughout the general cat population, having been carried for centuries. So a longhaired kitten in a litter of shorthairs is entirely ordinary and says nothing about the parents' ancestry beyond that both carried it.

Which is why long hair does not indicate a breed

This is the point people most often get wrong. A long, dense, impressive coat is what a Maine Coon has, and it is also what a great many domestic longhairs have, for the same genetic reason and with no relationship at all.

Is it a Maine Coon, or just a big fluffy cat covers the specific case. The general principle is that a single recessive trait present across the whole population cannot identify a breed.

Semi-longhair

Not a genetic category. It describes a coat that is long in the guard hairs but sparse in undercoat, so it hangs and flows rather than standing out dense.

Maine Coons, Norwegian Forest Cats, Siberians and Ragdolls are all described this way, and so are a great many random-bred cats.

The coats that do indicate something

Where a coat is produced by a rare mutation rather than a common one, it becomes informative.

Rex coats — curly or wavy — come from several distinct mutations, each associated with a particular breed group: Cornish Rex, Devon Rex, Selkirk Rex. A genuinely curly-coated cat has one of these, and it is a real narrowing.

Hairlessness in the Sphynx comes from a specific variant of the same gene affecting the Devon Rex.

The wirehair coat is another single mutation, and it is rare.

These are uncommon enough that seeing one is meaningful, which is the opposite of the long-hair case.

Practical consequences

Coat length determines grooming needs, matting risk and shedding volume, and those matter more day to day than any breed question.

A dense double-coated cat needs regular combing to prevent mats, particularly behind the ears, under the arms and along the belly. A mat that has formed close to the skin cannot be brushed out and needs clipping, ideally by a groomer or a vet rather than with scissors — cutting a mat off a cat causes a surprising number of skin injuries.

Most cats are not a breed at all, which is the broader point in most cats are not a breed, and their coats follow the same rules regardless.

Seasonal coats

Cats moult, and a long-coated cat in summer can look substantially shorter-coated than the same animal in February. The ruff around the neck and the tail plume are usually the last to go and the first to return.

That matters for identification because a photograph taken in August underrepresents the coat. Judging a cat's coat length in mid-moult is the least reliable moment to do it.

Grooming a cat that will not be groomed

Long-coated cats need help and many object. Short sessions, starting where the cat tolerates it and stopping before it objects, work better than one long attempt.

A cat that has become badly matted needs a groomer or a vet rather than home scissors. Skin under a mat is thin and tents up into the mat, and a very high proportion of home mat-cutting ends in a cut requiring stitches.