Chinchilla

The rat variety called chinchilla is genetically very unlike chinchilla in the mouse. In the mouse the chinchilla colouration is caused by a c-locus mutation, and the white belly either by separate spotting genes or a locus mutations. In rats, there is a dominant white spotting gene which can also have the effect of bleaching the yellow banding in the fur to give the chinchilla colouration.

This white spotting gene is linked with an illness called megacolon, and some kittens in most chinchilla litters will fall victim to this which causes death at around 3-5 weeks of age. No cure is known, and although very heavy inbreeding can all but eliminate this problem, it will reoccur immediately on outcrossing. Not many breeders work with the chinchilla variety because of this.

Although I have not been able to find much information on the chinchilla variety, the spotting gene is dominant and in most cases gives the animal a large blaze. The bleaching of yellow pigment is very variable, so as well as the black/grey/white show standard chinchilla, "half chinchillas" with yellow pigment remaining are commonly bred (aka bronze chinchillas). The bleaching effect is only visible on agouti based animals - a black based chinchilla is simply a black Berkshire. The fading yellow is inherited separately from the chinchilla gene.

Rats who inherit two copies of the chinchilla spotting gene are almost completely white spotted rats, these kittens almost always die of megacolon.

When combined with h-locus mutations, the European chinchilla gene gives other markings such as collared, banded, cap-stripe, and turpin. These combinations further increase the chances of megacolon.

 

A/- s/s	Agouti
A/- Fy/- S/s	Bronze chinchilla
A/- fy/fy S/s	Chinchilla