Orange tabby cats

[Ublaz]

I've heard that it is theoretically impossible for an orange tabby to be female, but a stray that we've adopted just had one! If we aren't mistaken and she is in fact female, what is the probability for this?

[Squirrel]

I know that "tortoise-shell" cats can only be female, but I have never heard of orange cats only being male.

The reason tortoise-shell cats are always female is basically because of the X chromosome. In the nucleus of every cell of every animal, along with the chromosomes that control what species you are and exactly what makes you how you are, there is one pair of slightly different chromosomes. In females, this pair is much like all the others, and consists of two same-length "X" chromosomes. In males, there is one X and a shorter "Y" chromosome.

Because the Y chromosome is shorter it is missing many of the alleles (variations of a gene, e.g. blue eyes / brown eyes are different alleles but are variations of the eye colour gene) that are present on the X. A fur colour gene in cats is located on a part of the X chromosome that the Y chromosome does not have a matching half for. (E.g. if the fur colour gene was on the nail of your middle finger, the Y chromosome would be your little finger.)

There are such things as dominant and recessive alleles. Usually, a dominant allele masks the effect of a recessive one (so if you inherit a dominant hair colour allele with a recessive one, only the dominant one will be your hair colour. E.g. D for brown hair is dominant over d for ginger. If you inherit Dd or dD or DD, you will have brown hair.) Some alleles are co-dominant, that is, neither masks the effect of the other and you in fact get a mixture of both. A fur colour gene in cats has two co-dominant alleles.

Female black or orange cats simply have a fur colour allele on each X chromosome. Males only have one X chromosome and therefore one fur colour allele. I will use:
B = black fur
b = orange fur

[Squirrel]

A male cat can either inherit a single B allele (X^BY) for black fur, or a single b allele (X^bY) for orange fur.

A female cat can inherit:
' X^BX^B for black fur,
' X^bX^b for orange fur, or
' X^BX^b or X^bX^B which both give a tortoise-shell coat (orange and black patches randomly arranged).

Sorry if none of this information is relevant to you! The reason females might not usually be orange could be similar to why so few women are colour-blind compared to men. If the orange fur allele is rare in the first place, then female cats are extremely unlikely (compared to males) to be orange because they would have to inherit two orange fur alleles whereas a male would only need one in order to have orange fur. In the case of a female cat being orange, the father would have to be orange, and the mother either orange or tortoise-shell.

(Source of information: Advanced Biology: Principles & Applications, C J Clegg)

[Ember]

Can't help with the science bit, but I too thought all orange cats (ginger) were male, i.e. Ginger Tom, never heard Ginger Queen referred to?

[thewillow]

Science isn't my area but you can definitely find orange/ginger females. My mother had one years ago. I have been told, however, that they are prone to feline leukemia.

[caz2uk]

I also thought that all ginger tabbies were male, until a stray turned up on our doorstep last year and is most definitely female!!!

[wildwood]

There are indeed ginger females, and Squirrel is correct in his summation that they are rare because in order for a female to show Ginger they would have to inherit the ginger carrying X chromosome from both parents.
The ginger colour in cats is called a 'sex-linked recessive' mutation, because it is carried on the sex chromosomes. To keep it simple, Females can be Ginger or Carriers. Males can not be carriers as they only have one X sex chomosome.
All the daughters from a ginger Tom will receive one ginger allele (carrier, because it is recessive to the non-ginger allele).
All the sons from a ginger Queen will receive one ginger allele (ginger, because males only have one X chromosome)
Half the sons from a Carrier mother will be ginger, they would inherit either a X chomosome with the ginger allele or one without.
Only when a ginger male mates with carrier female is a ginger daughter possible. All the progeny from a Ginger to Ginger mating will be ginger.
There are other mutations such as dilution that can mix with ginger and give a lighter colour.

[ihave19cats]

its not impossible to have an orange female, I have 3 myself. However, Squirrel was wrong when he/she said that tortoiseshells can only be female. I have 2 tortoiseshell males, if they are sterile or not still remains to be seen.

[mkcwebmaster]

People often say all tortoise shell cats are female, however a neighbour of mine where i used to live definitely had a male one.

[cathna]

I have 2 female orange tabby cats, both from the same calico mother (father unknown). Interestingly, one is a classic tabby, one is a mackeral tabby. As to male calicos, we have an orange & white male who has one very large black spot on his flank about the size of a human hand, but the vet says that's not enough for him to be considered a calico.

[KateB]

I have a female orange tabby, my vet also said they had only seen 1 other.

[calico_lover]

tortoise shell and calico cats are almost always females. Males are few and far between and they are sterile.

[jessieo10]

I think that the probability of finding a orange tabby cat is slim to none. I have never come across one in my life.