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I've noticed frequent comments in this forum discussing whether a cat is a "mediumhair" vs. "longhair."
Genetically, a cat is either shorthaired (has one or two copies of the dominant gene for short hair), or longhaired (has two copies of the recessive longhair gene). If you are curious about what genes your cat carries, you can have your cat's DNA tested. Here is information from UC Davis about longhair genes found in cats: Cat Long Hair
There is no gene for "mediumhair" or "semi-longhair" -- genetically, a cat is either shorthaired or longhaired. However, there are polygenes that contribute to coat texture and affect the density and appearance of the coat in both shorthairs and longhairs.
British Shorthairs, for example, have been selectively bred since the 19th century to have an extremely dense and plushy coat. They are believed to have the most dense coat (hairs per square inch) of any breed. This is the result of polygenes that have accumulated over time through selective breeding for the plushest possible coats. A cat that is otherwise the same as the British Shorthair, but with two copies of the longhair gene, is a British Longhair. The British Longhair has a long thick coat that requires daily grooming, similar to that of a Persian; the density of the coat is due to the same polygenes that make the British Shorthair's coat so thick and plush. British Longhair-Introduction
On the other hand, a Siamese has a flat coat that is not plush at all. The Siamese has been selectively bred for many generations for a sleek, close lying coat that shows off the slinky body type of the breed. A cat that is otherwise exactly the same as the Siamese, but with two copies of the longhair gene, is a Balinese. The Balinese has a relatively flat long coat that is not plush at all; this is due to the influence of the same polygenes that contribute to the flat coat of the Siamese. Breed Profile: The Balinese
You might call a breed like the Balinese a "semi-longhair" because its coat is not as full as a Persian, but genetically the Balinese is a longhair just like the Persian; it actually has the same longhair gene (M4) as a Persian and it is genetically M4/M4 just like a Persian. "Semi-longhair" just means a longhair that doesn't have a whole lot of hair.
There is no such thing as a "medium-hair" or "semi-longhair" gene. Here is an example of INCORRECT information that you will find on the Internet:
The FAQ on this site (here on TCS) is also a bit misleading:
If a cat has a long, flowing tail, it is a longhair and it is homozygous for the longhair gene. Mating two longhairs will always result in longhairs, because the longhair gene is recessive.
Saying that a semi-longhaired cat "may be the result of a longhaired cat mating with a shorthaired cat" is a bit misleading because the genes for hair length don't really mix that way. If you mate a longhaired cat with a shorthair that does not carry the longhair gene, you will get only shorthairs, but all of them will carry one copy of the recessive longhair gene. If you mate a longhaired cat with a shorthair that carries the longhair gene, you will get some longhairs and some shorthairs; the shorthairs will all carry the longhair gene.
It's fine to use the term "semi-longhair" or "medium-hair," as long as you keep in mind that this just means a longhaired cat that doesn't have a whole lot of coat.
Genetically, a cat is either shorthaired (has one or two copies of the dominant gene for short hair), or longhaired (has two copies of the recessive longhair gene). If you are curious about what genes your cat carries, you can have your cat's DNA tested. Here is information from UC Davis about longhair genes found in cats: Cat Long Hair
There is no gene for "mediumhair" or "semi-longhair" -- genetically, a cat is either shorthaired or longhaired. However, there are polygenes that contribute to coat texture and affect the density and appearance of the coat in both shorthairs and longhairs.
British Shorthairs, for example, have been selectively bred since the 19th century to have an extremely dense and plushy coat. They are believed to have the most dense coat (hairs per square inch) of any breed. This is the result of polygenes that have accumulated over time through selective breeding for the plushest possible coats. A cat that is otherwise the same as the British Shorthair, but with two copies of the longhair gene, is a British Longhair. The British Longhair has a long thick coat that requires daily grooming, similar to that of a Persian; the density of the coat is due to the same polygenes that make the British Shorthair's coat so thick and plush. British Longhair-Introduction
On the other hand, a Siamese has a flat coat that is not plush at all. The Siamese has been selectively bred for many generations for a sleek, close lying coat that shows off the slinky body type of the breed. A cat that is otherwise exactly the same as the Siamese, but with two copies of the longhair gene, is a Balinese. The Balinese has a relatively flat long coat that is not plush at all; this is due to the influence of the same polygenes that contribute to the flat coat of the Siamese. Breed Profile: The Balinese
You might call a breed like the Balinese a "semi-longhair" because its coat is not as full as a Persian, but genetically the Balinese is a longhair just like the Persian; it actually has the same longhair gene (M4) as a Persian and it is genetically M4/M4 just like a Persian. "Semi-longhair" just means a longhair that doesn't have a whole lot of hair.
There is no such thing as a "medium-hair" or "semi-longhair" gene. Here is an example of INCORRECT information that you will find on the Internet:
Domestic Medium Hair Cat Breed Information and Pictures - PetGuide
"The main difference between the Domestic Medium Hair, the Domestic Longhair, and the Domestic Shorthair is the fact that the Medium Hair has a medium-coat gene that produces its rarer, distinctive fur."
"The main difference between the Domestic Medium Hair, the Domestic Longhair, and the Domestic Shorthair is the fact that the Medium Hair has a medium-coat gene that produces its rarer, distinctive fur."
The FAQ on this site (here on TCS) is also a bit misleading:
What Breed Is My Cat?
"Sometimes, a cat has neither long or short hair, as their hair length falls somewhere in the middle. Some cats are simply medium haired! These cats are often known as 'semi-longhaired'.
Your semi-longhaired cat may have had two semi-longhaired as parents, or he may be the result of a longhaired cat mating with a shorthaired cat. These cats tend to have a thick, bushy undercoat and silky hair, with a long, flowing tail. Some medium-haired cats also have a longhaired 'mane' of hair on their chests."
"Sometimes, a cat has neither long or short hair, as their hair length falls somewhere in the middle. Some cats are simply medium haired! These cats are often known as 'semi-longhaired'.
Your semi-longhaired cat may have had two semi-longhaired as parents, or he may be the result of a longhaired cat mating with a shorthaired cat. These cats tend to have a thick, bushy undercoat and silky hair, with a long, flowing tail. Some medium-haired cats also have a longhaired 'mane' of hair on their chests."
If a cat has a long, flowing tail, it is a longhair and it is homozygous for the longhair gene. Mating two longhairs will always result in longhairs, because the longhair gene is recessive.
Saying that a semi-longhaired cat "may be the result of a longhaired cat mating with a shorthaired cat" is a bit misleading because the genes for hair length don't really mix that way. If you mate a longhaired cat with a shorthair that does not carry the longhair gene, you will get only shorthairs, but all of them will carry one copy of the recessive longhair gene. If you mate a longhaired cat with a shorthair that carries the longhair gene, you will get some longhairs and some shorthairs; the shorthairs will all carry the longhair gene.
It's fine to use the term "semi-longhair" or "medium-hair," as long as you keep in mind that this just means a longhaired cat that doesn't have a whole lot of coat.
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