Why does my cat bite his nails?
I actually love watching a cat spread her hind toes and then fastidiously nibble each little claw in succession. It’s positively adorable.
But why do cats bite or chew their nails? Is it a behavior you should be worried about?
Nail biting in humans is thought, at best, to be an unsanitary habit. But if nail biting in people becomes obsessive, or uncontrollable, it’s actually considered to be a psychological disorder. There’s a scientific name for nail biting: onychophagia.[1]
It’s a little like that in cats. A certain amount of nail biting is completely normal and part of a cat’s healthy grooming routine. There’s actually a couple of very good reasons cats like to tend to their toes, and I’ll discuss them in a minute.
But cats can sometimes take a good thing too far, and, like people, too much biting around the toes can be a sign of a psychological or medical problem.
You’ll need all your powers of kitty observation to tell the difference between healthy and unhealthy nail chewing.
The healthy reasons cats bite or chew their nails
Cats care a LOT about personal hygiene and spend up to half of their waking hours grooming themselves.
A kitten starts life with a grooming session, thanks to mom, and is already grooming himself and his littermates at the tender age of four weeks.
A cat’s body is designed for grooming. A cat has an unusually flexible spine with super-supple disks between each vertebra, allowing her to practically fold herself in half to reach the furthest corners of her body.[2] A cat’s tongue is really a hairbrush: firm little hooks on the tongue, called papillae, untangle and cleanse the fur.
A cat is basically a grooming machine.
A cat’s nails get dirty, just like ours
It makes sense that a cat who grooms every inch of his body would not neglect his paws.
Have you looked at your own nails after a long day of working on the car, digging in the garden, or playing with your toddler? Better yet, don’t look. Just wash!
A cat’s paws and claws can collect debris from the surfaces she walks on, or digs in, such as dirty cat litter. Skin oils and dead skin cells can also build up on the nails. You may notice an oily gunk building up around a cat’s nail sheath on occasion.
It is a cat’s job to carefully remove any filth that has gathered up between the toes, in the toe tufts, or under and around the nails. A cat who is nibbling her toesies in the holy pursuit of hygiene should be applauded.
Do not worry about this kind of claw chewing.
Cats need manicures, too, sometimes
A cat’s claws are very unusual. Although cats’ claws are often compared to human fingernails, they’re actually very different. Our nails are just connected to flesh, while a cat’s nails are connected to bone, and grow out of special structures in the toes that give the claw its signature curve and hard, pointed tip.
Until fairly recently, scientists didn’t really know how cats keep their claws sharp and in good working order. A 2009 study of the structure of cats’ claws using special imaging techniques finally shed light on the process.
We now know that cats shed the outer layer of their claws constantly, and how they do it. Tiny “microcracks” start to form on the outside of each claw, which multiply as a cat applies pressure, by climbing or scratching.
When enough cracks accumulate, the damaged outer layer falls off naturally. This continuous shedding of the outer layer ensures that a cat always has a sharp claw tip. Sharp tips keep a cat from getting stuck in whatever he’s just sunken his claws.[3]
Sometimes, an almost-shed claw sheath needs a little help. If a hanging piece of nail is getting caught on things, a cat might just finish the job with her teeth.[4]
This, too, is a perfectly healthy reason a cat will chew or bite his claws.
Reasons to worry about nail biting in cats
Sometimes, nail biting or chewing is sign of something more worrisome.
If a cat, who wasn’t a big nail chewer, suddenly starts chewing obsessively, you must consider a medical or behavioral cause for the change in behavior.
Reach out to your vet if your cat’s nail biting seems out of character for her.
Medical reasons for nail biting in cats
- Skin infections of the toes, paw pads, or nail beds, whether bacterial or fungal in nature, can cause itching or discomfort.
- Allergies, parasites, such as fleas or mites, or overly dry skin can also cause a cat to lick, chew, or bite her paws.
- Paw pain due to an injury can also cause a cat to obsess over his feet.
- Autoimmune diseases, such as pododermatitis, which causes painful swelling of the paw pads, could cause cats to lick or chew their paws.[5]
Look for other signs that something is amiss, including hair loss, skin redness, swelling, flaking skin, and tenderness, any of which could indicate a medical cause for nail biting. Contact your veterinarian as soon as possible.
Behavioral reasons for nail biting in cats
There is a really, really fine line between normal nail biting in cats and excessive nail biting in cats.
The best person to tell the difference might be you. You know, better than anyone, what is “normal” behavior for your cat, and what is not.
Is your cat suddenly hiding more, or meowing excessively? Is he suddenly peeing or pooping outside of his litter box, or did he suddenly start spraying? If your cat is experiencing emotional discomfort, nail biting may be accompanied by other signs of distress.
What are some potential behavioral causes of unhealthy nail biting or chewing in cats?
A change in routine
Cats like routine and predictability. Even the smallest changes in your household – like a new piece of furniture in living room, or a new type of litter in her box, can cause a cat’s whole world to come crashing down.
Big changes: a new baby, the death of the family dog, the addition of another cat to the household, a new job that causes you to come home an hour later in the evening, can be very anxiety-producing for cats.
Take a hard look at your life from your cat’s point of view. What can you do to mitigate change? You can’t send the baby back, but can you make sure to feed the cat at his usual times? If there’s a new cat in the house, can you take a step back and start the introductions again, but this time more slowly?
(Read this post, "How to introduce a new cat to your cat.")
Boredom
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Boredom is, unfortunately, common in indoor cats.
If you suspect your cat is biting his nails out of boredom, find more time to play with him. Cats enjoy short play sessions: 10-15 minutes at a time, several times per day. I wrote this blog post on nine fun ways play with your cat during quarantine, but these activities are entertaining any time.
Provide an enriched home environment to keep your cat busy when you can’t be there to play with him. Put a kitty seat, like this hammock by Zalalova, by a window and hang a bird feeder, such as the Squirrel Buster, nearby.
Leave foraging toys around the house to challenge her intellect. A simple treat ball, like this one by Catit, or an inexpensive LickiMat, are good “beginner” choices.
Provide tunnel toys, and climbing structures for mental and physical stimulation. A catio, which is an indoor/outdoor cat enclosure (like this one by PawHut), is the Rolls Royce of anti-boredom devices.
Read these related posts:
Why do cats groom or lick each other?
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Dawn LaFontaine is a lifelong animal lover who always seems to have a little pet hair in her keyboard. Her blog, Kitty Contemplations, helps cat guardians better understand and care for the special beings they share their lives and homes with. Her cat-products business, Cat in the Box, sells beautiful, well-made, and award-winning products that she designed to meet the biological needs of cats.
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FOOTNOTES
[1] “Onychophagia (Nail Biting).” Psychology Today, Sussex Publishers, https://www.psychologytoday.com/us/conditions/onychophagia-nail-biting.
[2] Spanner, Andrew. “Overgrooming, Over Licking & Hair Loss In Cats.” Walkerville Vet, 28 Nov. 2020, www.walkervillevet.com.au/blog/cat-hair-loss-causes/.
[3] Homberger DG, Ham K, Ogunbakin T, Bonin JA, Hopkins BA, Osborn ML, Hossain I, Barnett HA, Matthews KL 2nd, Butler LG, Bragulla HH. The structure of the cornified claw sheath in the domesticated cat (Felis catus): implications for the claw-shedding mechanism and the evolution of cornified digital end organs. J Anat. 2009 Apr;214(4):620-43. doi: 10.1111/j.1469-7580.2009.01068.x. PMID: 19422432; PMCID: PMC2736126. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2736126/
[4] “Nail Biting in Cats.” PetMD, https://www.petmd.com/cat/behavior/nail-biting-cats.
[5] MantPress. “Pododermatitis in Cats: How Is It Cured?” Hospital Veterinari Glòries, 16 Nov. 2021, https://www.hospitalveterinariglories.com/pododermatitis-cats-2/?lang=en#:~:text=Pododermatitis.