Breeding with MC polys is an easy decision, as it is a dominant trait you need a poly parent to make poly kittens. The kittens in a MC x MC poly mating will give variable amounts of poly to non poly kittens, but statistically the chances are half way, 50%. These kittens if poly are then heterozygous. With this combination it is also easy to follow the pedigree line back to see the origin of your MC poly cat. If one were to mate two heterozygous MC poly cats together, then statistically 75% of kittens will express the trait, these kittens will be heterozygous and possibly homozygous. It is more difficult to follow the origin of the poly line further though.
If one were to mate a homozygous MC poly to a regular pawed Maine Coon all offspring will be poly, all heterozygous. If two homozygous MC polys are mated then all kittens will be homozygous MC polys of course. This has no detrimental effects for the cats whatsoever (see Research #4). Kittens of two polydactyl parents do not show statistically higher numbers of digits than poly to straight-foot breedings. This has been shown in Danforth’s observations and has been confirmed by the collected data of PolyTrak.
Per Dr. S. Pfleuger: “Although the number of extra toes varies from cat to cat, a total of 28 toes seems to be the upper limit.”
Poly x Poly breedings: (source: PolyTrak data 2014)
Traditionally, a P or PP is placed in the pedigree name to show that the cat is polydactyl. Since not every breeder follows this format, however, there has been no reliable way to track poly ancestors. In TICA, following the formation of a Maine Coon breed group (MC/MCP), kittens produced from a poly mating will have SBV instead of SBT preceding their registration number for three generations, thus allowing easy identification.
Maine Coon Polydactyl cats play an important role in the heritage of the Maine Coon breed and add diverse pedigrees to the gene pool. They are used in all types of mating, whether foundation, outcross, or show lines, and few pedigrees are without a polydactyl ancestor.