Polydactyly in cats

The special thing here is obviously. As a rule, cats have 5 toes on their front paws and 4 on their hind paws. Cats born with polydactyly have several toes each. Here you can find out how the so-called “multi-toedness” can affect the health of our beloved cats.

How many toes do cats normally have?

As mentioned in the introduction, cats have a total of 18 toes with the corresponding claws: There are 5 toes on each front paw and 4 toes on each hind paw. The fifth toe is similar to the human thumb and is located on the inside of the front paw, usually a little higher. This thumb claw usually does not touch the ground and is of great importance especially when hunting.

But why do cats have only four toes on their hind legs? We humans also have a big toe. Why nature has decided to equip cats with only four toes on their hind feet remains a mystery to us so far. 

However, it is assumed that the ancestors of our domestic cats had a fifth toe on their hind legs. A small rudiment, a tiny remnant of this, can still be seen in some cats. Take a closer look at your pet’s hind paw, can you see that little knob on the inside of the hind paw?

Good to know: Very rarely cats are still equipped with this fifth toe, it is popularly known as the wolf’s claw or the anal claw. 

What is polydactyly?

Cats with this anomaly (malformation) live on a large foot, so to speak, they are born with more (partly deformed) toes. This is why polydactyly is also called multi-toedness. There are different forms of polydactyly. 

In the most common form, each paw has one toe with an additional claw. Thus the kitten is born with 6 toes on the front paws and 5 toes on the hind paws. Mostly the additional toe is formed on the inner or outer side of the paw (preaxial versus postaxial). However, it can also happen that the extra limb forms in the middle. 

Sometimes it happens that only one paw is affected or all but one. It can also happen that several extra toes form on each paw. A cat named Jake has even made it into the Guinness Book of Records. He leads the rank with an unbelievable 28 toes. 

Some cats have concomitant (anatomical) abnormalities of the carpus and tarsus. Loss of the sesamoid bone up to fusion with neighbouring bony structures is also possible.

Fun Fact: The furry roommate of the author Ernest Hemingway named “Snow White” was a polydactyl cat. Accordingly, these cats are also popularly called “Hemingway cats”.  

What forms of polydactyly are there?

Basically, a distinction is made between two forms:

1. The Mittens form: In this form, the extra limb forms on the inside of the paw. This toe resembles a human thumb. For this reason the paw resembles a mitten or a boxing glove. 
2. The patty-foot shape: Here the cat’s paw looks like a hamburger patty. In this type the extra toes grow either on the outside of the paw or in the middle.

How does polydactyly develop?

This disorder is caused by a congenital gene mutation. A particular gene, called the sonic hedgehog gene (SHH), is significantly involved in the formation of extra toes.  Unfortunately, this gene mutation is inherited in an autosomal dominant manner. This means that it only takes one parent with this mutation to pass it on to their offspring. There are no gender-specific differences.

Important: Polydactyly is congenital and the extra toes usually have an associated claw. If your darling grows an apparently additional, clawless “little toe” only in adulthood, a veterinarian should be consulted in any case, because in the worst case it can be a tumour. 

Are there cat breeds which tend to polydactyly more often?

In principle, this gene mutation can occur in any cat. However, there are cat breeds that are statistically more prone to it. These include:

• Maine Coon 
• American Polydactyl (recognised as a separate breed in the USA)
• Pixiebob

What health problems can polydactyly cause?

These mutated paws may look cute to some people, but they can also pose some health risks to our beloved pets:

• Changes in the bone structure (toe and metatarsal bones).
• These bony changes can have an impact on mobility.
• This malposition can lead to pain, due to one-sided wear and tear.
• The risk of injury increases. The extra toes tend to tear in or, in the worst case, tear out. Some cats also get caught on objects or the like much more often and can hurt themselves. 
• Possible open wounds increase the risk of inflammation and infection.
• Unused claws can grow in more quickly. 

Tip: If your cat has too many toes, pay special attention to claw care and trim unused claws regularly to prevent them from growing in and causing pain and increased risk of injury.

“Superscratcher” versus torture breeding.

In America, it is sometimes a little differently. They even breed their own polydactyl cat breeds, so-called “superscratchers”. The possible health consequences are usually ignored there. It is advertised that cats with extra toes have a considerable advantage over “normal” cats, quasi possessing a “super power”. In America, superscratchers are said to be better at climbing and keeping their balance. This remains uncommented at this point.

In Germany, the situation is somewhat different: According to §11b of the German Animal Welfare Act, cats with the described genetic mutation are classified as torture breeding. This means that in Germany there is a breeding ban depending on the degree of expression. Exhibiting them is also prohibited in Germany. 

This decision is justified by the fact that it is a transformation of a body organ (toes) with partial functional restriction. There is also an expectation of damage, suffering and pain. Furthermore, animal protection argues that the cat has to live with a restriction of the species’ own expressive behaviour.   In Austria, the Animal Protection Act also prohibits the unjustified infliction of suffering, pain and harm on animals. From the above point of view, polydactyly in cats is therefore to be classified.