When I was a kid we ended up with a
great mouser named Rusty. He was a
red tabby and had ten toes on the back, thirteen toes on the front. Almost all of the
polydactyl cats have
mirrored feet (same number of toes on each front paw and the same for the back set). Rusty had his thirteenth toe stuck between where the thumb and index finger appear on a human hand, on the left paw.
Rusty was an astounding mouser, and we never had a problem with mice even though we lived at the top of a remote mountain in the Adirondacks. Any little creature that dared enter ended up cat snacks. The family was woken several times to the crunching sounds of Rusty eating half a mouse.
Polys do have problems with nail trimming. Even though we let Rusty roam about (no other cats in the area, so no kittens in the wild!), it never wore the nails down. It's true that the extra toes grow nails faster, and holding down a 25-lb cat to trim nails is not a fun task. Rolling the cat in a bedsheet worked well.