Why Do Cats Eat Grass? The Mystery of the Lawn Meowers

There is something quite strange about seeing a cat, one of the world’s most committed carnivores, enthusiastically snacking on grass. What is even stranger is that although eating plant material is an extremely common behaviour (it’s estimated that as many as 90% of cats indulge in a little greenery at some point in their lives(1)) there is not a definitive understanding about why.

There are, however, quite a few plausible theories:

1. Probably the most common belief about why cats eat grass is to help them vomit when they feel sick and need to purge. This could help them to get rid of a hairball, or the bones or feathers from catching small prey. However, in one survey, only about a quarter of cats were observed to vomit after eating grass and most of them did not show any signs of illness beforehand(1); which suggests that the need to purge most likely does not account for all cases of this herbivorous habit.

2. A more recent theory is that grass eating is an evolutionary behaviour that served the purpose of increasing motility of the gastrointestinal tract and so helped to eliminate parasites(1). Even though modern cats are in general better protected against worms than their ancestors, the behaviour has remained.

3. Another possible reason is that grass contains folic acid, so a cat deficient in this vitamin may eat grass to try and supplement themselves. Fortunately for our feline members of the KatKin club, this should not really be applicable to them, provided they don’t have a medical condition which prevents the normal absorption of nutrients. Folic acid requirements are carefully considered and included in our highly nutrient dense meals.

4. Lastly, eating grass may act as a laxative to help cats with constipation, thanks to the extra bulk and fibre it provides.

All of these reasons are different potential explanations for a rather quirky behaviour, and it’s also possible that some cats just enjoy the flavour and texture of certain grasses. A small amount of grass eating is usually harmless, provided that the grass has not been treated with chemicals, which may be dangerous if ingested. Of course, accidents can happen – a grass seed awn may become lodged in the nose, or very rarely the grass itself could cause a blockage, but this is certainly the exception rather than the rule.

It’s possible to provide your cat with her own personal patch of lawn in the form of a feline herb garden. These are usually oat or wheat grass which are generally preferred by cats. The benefit of these is that they can be kept indoors, and you can be certain that they have not been treated with any potentially toxic substances. They also offer a form of environmental stimulation for indoor cats.

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References

1. Shultz, D. (2019, August 8). Mystery solved? Why cats eat grass. Science. Retrieved from: https://www.sciencemag.org/news/2019/08/mystery-solved-why-cats-eat-grass