Mink Rats

 

The workings of the mink and pearl genes are long since understood and accepted. Mink is a simple recessive gene, turning black pigment to a mid brown with a blue sheen to it. Pearl is slightly more complicated, turning mink rats into a glistening silver, almost white, but having no effect on black.

The accepted genotypes for mink/pearl based colours:

There are no known health problems associated with these varieties. The pearl gene is a "homozygous lethal", meaning an embryo that inherits two copies of the pearl gene (Pe/Pe) will never be born as it is not viable. This does not cause health problems in the variety, it simply means that litters from two pearl parents are smaller than average.


Sunnyside Texas Jim, a Russian dove ("mink" plus Russian blue, non-agouti)

The first Russian blue litters in the country produced not only Russian blues, but also a rainbow of dilutions. Some of these were identified as (English) blue based, some were based on red eye dilute, and others were assumed to be mink based. These shades were named dove (Russian blue plus mink, non-agouti) and Russian cinnamon (Russian blue plus mink, agouti). When one of these Russian dove does was bred to a pearl buck carrying chocolate from UK lines, only black kittens resulted in the litter - showing that not only was this gene not the same one responsible for English mink (or an allele on the same locus) but also suggesting that it is not at the same locus as chocolate.

 

Other lines that came into the country soon proved to have this "mink" gene. It is behind platinums (combined with blue), and many of the original dumbo lines threw "silver fawn" rats which were actually red eye dilute combined with this mink. It is commonly called "mock-mink" or "American mink". To avoid confusion, for the rest of this article I will refer to this colour identified in the imported lines as American mink, and the colour found in UK lines as English mink. Confusingly, English mink is also found in imported lines, although American mink is not found in pure UK lines.

 

Like English mink, American mink can be a range of different shades, from a very dark colour that is almost like chocolate or a very brown Russian blue to a lighter colour that is very like English mink but warmer. Many American mink based rats have merle spots, which is not something that normally occurs in English lines - some English lines are patchy in colour, but true merle spots appear as the fur is coming in and although their intensity may vary with the tone of the adult fur, their placement remains the same throughout life.

 

American cinnamon can be a very different shade to English cinnamon. Instead of the warm red shade that we normally see at shows, the American cinnamons can vary in shade from a bluish shade, to very dark. Through selective breeding and the removal of other recessives, American cinnamon does give a perfectly normal shade for UK shows.

 

Matings with American mink have given pearl type colours. One variation on this is similar to English pearl, but with dark ruby eyes and a warm creamy coat colour (as opposed to the black eyes and cold toned english pearls). The second variation is darker than English pearl, black eyed and often with dark merle spots.

 

Test matings have shown that the two genes both act as simple recessives, and appear to be affected by the same pearl gene. English mink is given the symbol "m"; American mink has been given the symbol "mo", which is not scientifically described, but serves to distinguish it from English mink.


Left, Flair of Alpha Centauri (English pearl) and right, Tethys McMahon (American pearl). This photo shows both of them as slightly darker than they actually are. It does however show the difference between the cold English colour and the warm American colour. You can also see the ruby glow to McMahon's eyes.