Chew on this! A new study looks at pica in cats

Pica, or the ingestion of non-food items, is found in species as varied as parrots, humans, and domestic cats. It’s unclear why some animals eat things that aren’t food – some guesses include stress and nutritional deficiencies. This behavior in cats was first noticed in Siamese cats, who are prone to sucking and eating woolen items. However, once all breeds (including the domestic shorthair) were included in studies, it became apparent that this behavior isn’t limited to the meezers in any way.

A new study, Characterization of pica and chewing behaviors in privately owned cats: a case control study, sought to better understand factors that might predict pica in cats, in the hopes of helping the veterinary community in developing effective treatments. This study surveyed 91 pet owners with cats who ingested non-foods, and included a control group of 35 cats who did not.

The researchers asked questions about basic kitty demographics, including age, breed, sex, medical history. They also included questions about the environment (including types of enrichment available, other people and animals in the house, and access to the outdoors). Finally, they asked questions about potential gastrointestinal signs, such as vomiting and diarrhea.

Some cats are attracted to eating strings and shoelaces. Photo "Cat on a strong" by Stefan Tell via Creative Commons/

All cats in the pica group ingested non-food items, with 79 of them also chewing (but not swallowing) other things on a regular basis. Twenty one out of thirty-five of the control cats (that’s 60%) also chewed on things that aren’t really chewables!

What do cats with pica like to “eat?” Perhaps not surprisingly, shoelaces, plastic, and fabrics were all in the top three. Other interesting choices included toilet paper, soap, ear plugs, kitty litter, and sponges. Plastic, paper, rubber, and wood were the chew-toys of choice for the cats who were chewing on items.

Three variables were prominently related to the presence of pica – the first was access to the outdoors. Although pica in cats has often been blamed on being kept indoors and bored, in this study, the pica cats were MORE likely to have access to the outdoors.

Fifty-one percent of the control cats had “ad libitum” access to food – meaning that food was freely available. This was only true for 30% of the pica cats, even though there were no differences in feline hunger ratings by owners between the two groups. Does having food freely available redirect some of that chewing behavior toward food?

Finally, more vomiting was found in the pica cats – but we have a chicken and egg problem in that we don’t know if the vomiting is caused by the chewing, or the chewing is an attempt to relieve nausea. This manuscript opens up interesting research questions about the behavioral signs of gastrointestinal disease, but also suggests that pica is not (at least in all cats) necessarily a stress-related or compulsive disorder caused by indoor housing.

The choices for chewing and eating are interesting to me – we still don’t know why things like plastic and fabric are so darn attractive to cats. And soap? Really? And although we don’t know the prevalence of true ingestion of non-food items in the general population of cats, it’s apparent that chewing behavior in cats is very common (60%) even in a control group of cats!

Pica in cats can be dangerous – in some cases, it can lead to expensive surgeries for gastrointestinal blockage. Pica and chewing can also cause damage to your war

Some cats love to chew on things that aren't food...why? Photo via Flickr/Creative Commons by Jessica Fiess-Hill
Some cats love to chew on things that aren't food...why?
Photo via Flickr/Creative Commons by Jessica Fiess-Hill

drobe, but of course, the burning question is – what does it mean? Is pica a sign of emotional distress or physical pain? Is it a nutritional deficiency? Is it brain chemistry gone awry?  Do cats just need appropriate chew toys? Still so many questions!

If you see your own kitty chewing or eating something that isn’t food, be sure to let your vet know before you have an emergency on your hands! In the meantime, this study chips away at the pica mystery, and brings up some interesting questions about how we feed and house our cats.

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12 thoughts on “Chew on this! A new study looks at pica in cats

  1. Thanks for another great article, Mikel! Out of my five cats, I have one who LOVES to lick plastic grocery bags and ziploc baggies. She doesn't eat them, but it's very curious! Anyway, pica has always been a mystery to me, and I generally treat it as a stress-related disorder. The results of the study you cited are interesting in that pica is not necessarily indicative of stress related to being kept indoors! The mystery continues, I suppose... 🙂

  2. Elizabeth Fox

    Our cat licks the couch, eats our straw that is in our drink, and eats our dental floss right out of our hands as we are flossing our teeth. When I learned about pica, I found a 1991 article, Feeding and Drinking Behavior Problems, that indicates pica in cats might be due to early weaning. The new articles suggests pica is not due to early weaning, and we suspected new research would contradict the 1991 article.

    1. Mikel Delgado

      Post author

      things are usually more complicated than we think! I think pica is a good example of that.

  3. Lisa McCaslin

    So interesting to me. I have two cats, brother & sister, that I've had together since they were 8 weeks old. They're 3 and a half now. The boy cat, Vinny, is an orange Tabby & definitely has feline pica. He goes crazy over plastic shopping bags and also bows and ribbons. The female, Summer, is a calico, and she's never chewed on anything but her food. So I have kind of my own controlled study I guess. They've been raised exactly the same way, same place, same food. Do they grow out of this?

    1. Mikel Delgado

      Post author

      Unfortunately we don't know if pica improves with age without interventions! However, some cats do improve with chew toys and other enrichment to keep them stimulated.

  4. Deborah Davies

    I have a new mom that was taken in a pregnant stray. Part of this will be learned behavior and the other a mystery but I thought the connection may be interesting. I have a small fishtank on my bathroom counter. With hindsight, momma wasn't after the fish but the water being filtered outside to inside. Before realizing this, momma learned she could even wake me up with the slightest sound of the top moving. It was her attention seeking way to rattle me running to the rescue of my fish. I used packing tape upside on the counter and secured the top with duct tape. Now it was rescuing momma from trying to tear the tape down. Well needless to say the tape had to be removed. Then she realized there was tape on boxes, glue on envelopes and finally cardboard to chew. She doesn't eat the cardboard just chew. Once she found cardboard the tape fetish stopped and envelopes weren't really her thing. I don't go running and it's not very often. The fact that the vacuum comes out more often may be her deterent! With her being a new mom of course I was worried about her having a mineral deficiency but the learned pattern is so right there.

  5. Jennifer

    Perhaps the study should include hormonal changes since pica is common during pregnancy in humans. I loved toothpaste during my second pregnancy which was my only “girl” pregnancy. I didn’t have it with the boys. My Haze (male cat) chews with intentions of digesting anything rubber.

  6. Really interesting.
    I did a small study on Pica (just 37 cats at all) on my own when doing my exam for feline behaviorist.
    I also found, that not only indoor cats but cats that can go outside whenever they want and even are good hunters can have Pica. That really seems to put away the theory of the bored indoor cat.
    Another interesting finding was: Some households seems to be kind of "Pica-households". When there is a cat that has Pica and a new cat is coming into the home, she also shows the behavior after a short time. It could be learning. Especially, if it is a kitten coming into the household. But also older cat shows Pica when coming new into these households. And some owners reported, that there old – now gone – cat had shown Pica and now the new one shows it as well! So I wonder, if there might be something in the house (some smell, some fabrics..?) or in the behavior of the owner (attention?) which triggers the Pica behavior. That is an interesting thing to look on in further studies.
    Otherwise the "attention"-theory didn't fit in as well, because a lot of owners reported, the cat shows Pica when there is nobody around and they will notice it when coming home, seeing things destroyed.
    So it is still a riddle and a big challenge for us feline behaviorists to solve Pica.
    Sometimes it could help to feed them row muscle and bones to chew on. In some cases you can reduce the problem, if you are lucky, but more often the cats will still show Pica in some circumstances.


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