When we think of cats and rabbits, we tend to think of them as very different species, and of course, they are! Whilst they share some broad traits such as being mammals, and having both wild variants and also being pets, the similarities on a surface level stops there.
After all, cats are predators and rabbits are prey animals, cats roam freely and aren’t what we consider as fully domesticated but rabbits tend to be kept in enclosures and can be completely tamed, and cats are of course carnivores and rabbits, vegetarian.
However, there is one interesting and unique coat trait that occurs in both some rabbit breeds and some cat breeds too, and which can even be found in other mammals including dogs and horses. So distinctive is this trait, and so in demand in some of the animals that display it in fact that it has served to form the foundation of entirely new breeds of both cats and rabbits, which have over time gone on to be afforded full pedigree status by the relevant authority bodies.
What is it? It’s called the rex mutation.
You may have come across the term “rex” before as part of the name of certain cat and rabbit breeds, including the Devon rex and Cornish rex cat breeds, and the standard rex and Astrex rabbits.
So, what type of gene mutation is so unusual and interesting as to have formed the foundation of several whole new breeds, and across two entirely different pet species like cats and rabbits? One that results in curled fur in the animals in question!
In this article we’ll look at the interesting and unique rex gene mutation that can be found in both rabbit and cat populations, how it came into being, and what it does.
Read on to learn more about the rex gene mutation in cats and rabbits.
The rex mutation is a type of genetic mutation or variation from the genetic norm/normal behaviour of a gene that causes animals that possess it to have distinctive fur that is both soft and curly, when this is not the standard or genetic norm for the species in question.
This mutation expresses across the whole of the animal’s coat, and might result in very tightly curled coiled fur that lies very close to the skin, or simply result in a broken, disrupted or waved appearance when this is not the norm.
The rex mutation results in the animal that displays it having what is known as a “rexed” coat.
The mutation in question can occur in isolated animal populations very occasionally on its own and not as a result of outcrossing with other animals of the same species that possess it, and this is in fact how the various rabbit and cat breeds that possess it first came into being.
The rex mutation affects the construction of the fur itself at a cellular level, changing the structure of each individual hair and the patterning of hair distribution within the coat too. The length, thickness and exact texture any rexed coat displays, however, can be variable across breeds and species displaying it.
Coat mutations that result in curling in species that otherwise don’t display this are almost universally referred to as rex mutations; however, they do not all affect the exact same gene in every animal species that exhibit it, or even in every breed within the same species.
Even in cases where rexing occurs in different breeds or species within the exact same gene, the way they affect it can vary.
A good example of this comes in the form of the Cornish Rex and Devon Rex cat breeds; both display rexed coats, and even originate from neighbouring counties, as well as having the very first cats that founded the two respective breeds discovered within a few years of each other.
However, whilst the Cornish and Devon Rex cat breeds respectively both inherit their rexed coats due to a mutation on the same gene, the mutation itself is different, resulting in these two cat breeds being classed as separate and independent of each other accordingly.
The rex gene mutation in cats and rabbits is hereditary, and passed on from parents to their young by means of autosomal recessive heredity. That means that if just one of the parent cats or rabbits in question has a rexed coat but the other parent has a normal coat, their subsequent offspring will have normal, not rexed coats.
The exception to this is if a cat or rabbit carries one copy of the rex gene (which makes them a carrier of it) but not two, which means they don’t display the trait themselves.
Breeding a carrier with a rexed parent, or breeding two carriers together, is apt to result in mixed odds or a combination or unpredictable mixture of rexed and non rexed offspring!
What cat breeds display the rex gene mutation?
The four best-known and widely recognised cat breeds with curled coats, or cat breeds with rexed coats, are:
The Cornish Rex
The Devon Rex
The Selkirk Rex
There are quite a lot of recognised rabbit breeds and variants that display rexed coats, and in several such breeds, the exact genes in question have been pinpointed and individually identified. Some of the best-known rabbit breeds that display rexed or curled coats are:
The breed simply known as the Rex, which is the only really widely-seen rex breed within the UK.
Cats and rabbits with rexed coats are unusual, but this trait can also be found in a wide number of other species too; including the horses and dogs we mentioned earlier; but also hamsters and Guinea pigs as well, like the rex Syrian hamster and rex Guinea pig.