BIMETALLIC BRITISH SHORTHAIRS
Many thanks to Martina Gottwald for photos and pedigree information on this page. "Bi-metallic" or "Bimetal" describes a visual effect wher both silver and golden are present on in the coat at the same time, but is more than normal rufism.p>Martina Gottwald has been breeding British Shorthairs for 23 years and has found the bimetallic trait in some breeding lines. Although most German breeders prefer not to acknowledge it, it seems likely that some champion “golden" tabby and “shaded” may be genetically different, for example the sunshine or bimetallic trait. Tinjas Silver Sally Sunshine (either A_Bb(1 or 2) Cc Dd ii genotype) was born as a “black silver” but developed the strange mix of silver and golden between the third week and the fifth month of her life. She is pure British Shorthair over many generations and her parents are unrelated (note – the registry allows Scottish Straights to be registered as British Shorthairs). She is intermediate between silver tabby and shaded and was a test mating to investigate the bimetallic trait. Her paws are black underneath and she has dark eyeliner – the same as seen in black golden (sunshine) Siberians. Intermediate between tabby and shaded/tipped is common when only one of the parents is tipped.
There is a close relationship between these cats and those in pedigrees of the "copper" phenotype described at Copper Phenotype in British Tipped Shorthairs