Q: My kitten has an extra toe, which makes it look as if she has on mittens. Is that normal, or is it a certain type of cat breed that has it?
A: Your cat has a condition called polydactylism, (from Greek: poly = many, daktulos = fingers). Normally, a cat has 18 digits. The front paw has five toes — four toes and one dewclaw (the small toe on the medial side of the foot that doesn’t touch the ground). Most polydactyl cats have one or two extra toes on each foot, with the extra toes appearing on the thumb side of the foot. The normal rear paw has four toes. Polydactylism is a common trait among cats.
Polydactyl cats are occasionally referred to as “mitten cats,” “thumb cats,” and “Hemingway cats,” the latter name referring to the writer Ernest Hemingway, who made his home on the small island of Key West, Fla. Hemingway shared the island with almost 50 cats, including a six-toed polydactyl named Snowball (or possibly Princess) given to him by Stanley Dexter, a ship captain and drinking buddy. For the next 100 years, unrestrained breeding between this cat’s descendents and the local cats (alas, they weren’t as keen on spaying and neutering as we are today) led to a high percentage (almost 50 percent) of polydactyls in the local population.
Hemingway isn’t the only famous person who is linked to polydactyl cats. President Theodore Roosevelt had a polydactyl cat named Slippers who was one of the first feline residents of the White House.
Polydactylism doesn’t affect cats adversely. It offers them no advantages, nor does it yield any disadvantages. (If it did, polydactyl cats most likely would have died out.) It is simply an enchanting quirk. I should know. My own cat, Mittens (very corny name, I know) is polydactyl, and it’s one of the things that charmed me about her. While people often worry about cats catching the extra toes on furnishings, this is rarely a problem. The toenails associated with the extra toes tend to be normal nails, although occasionally, the extra toe is incompletely formed, and the nail bed is deformed, leading to claw problems like ingrown or overgrown claws. Like all kitty toenails, the extra ones require regular trimming.
Arnold Plotnick, DVM