Why do cats eat grass just to throw it up?

March 5, 2004 8:10 AM

When I let my cats outside on a sunny spring day, the first thing they do is eat grass. They're like miniature lawnmowers. Later, they hack the grass back up (like a hairball). Why do they do this? (Meaning: why do they eat the grass in the first place, and why do they then spit it back up?)
posted by jdroth to Pets & Animals (13 answers total)

Here is an explanation of why they eat it.
posted by studentbaker at 8:15 AM on March 5, 2004

Back in the old country they say cats are "healing themselves" when they do this. Its cool to finally have this scientific explanation.
posted by azul at 8:23 AM on March 5, 2004

Cats eat grass for fiber, to get their veggie-vites, and also as an emetic when they've eaten too much. I witnessed this firsthand today when my beloved Pandora nibbled on her freshly grown cat oats after breakfast, jumped up on my bed, then promptly spewed a hairball onto the newly washed sheets.
posted by brownpau at 8:29 AM on March 5, 2004

Note that all the explanations given are just theories. To the best of my knowledge, we still don't truly know why they do this. I will say that buying cat grass (usually barley grass) that you can grow on a windowsill results in happier kitties and less barfing (grass on the lawn is usually of a variety with rough edges, and in my experience, it's the rough grass that makes then barf - cats eating softer grasses don't vomit as much).
posted by biscotti at 8:35 AM on March 5, 2004

Google: cat grass eat gives you an answer on the first page.
posted by five fresh fish at 8:55 AM on March 5, 2004

Response by poster: Okay, this all makes sense. But is there something I should know then from the fact that the first thing my cats want to do when they go outside is to eat grass? I mean, they don't get to go outside very often, especially in the wet Oregon winter. Should I be supplementing their diet (with cat oats, for example)?

One of the cats had a urinary tract infection last year, and now he's on prescription food (Science Diet C/D). Because he's on it, the other two cats are on it. Is it possible that they're not getting enough fiber because they're on this special food?

I'm a bundle of questions, aren't I?
posted by jdroth at 8:59 AM on March 5, 2004

There is no reason not to supplement them with cat grass (most pet shops sell it in a little tub), and many cats really enjoy it (it's also better for them than eating garden grass with who-knows-what on it). You can't assume that it's about fibre, since, as I said, we don't actually know why they eat it - all the theories are just ideas at this point, we don't have any concrete evidence that it's directly related to diet, constipation, or anything else. c/d is a decent food (it's not Science Diet, it's Prescription Diet - both are made by Hill's, but Science Diet is awful crap, while Prescription Diet is manufactured with a lot more care, and a lot less less roadkill/euthanized pets). There's also a lot of controversy about just how much fibre cats really need, since they're obligate carnivores, they would not naturally consume a lot of fibre in their diets, and much of the current thinking is moving away from routinely adding fibre to cats' diets for certain problems. Get them some cat grass, they'll love it.
posted by biscotti at 10:12 AM on March 5, 2004

kay, this all makes sense. But is there something I should know then from the fact that the first thing my cats want to do when they go outside is to eat grass?

That just means they're normal indoor cats, I think. Every indoor cat I've ever had went for the grass first thing when they got outside. That, and rolling around in the dirt.
posted by vorfeed at 11:13 AM on March 5, 2004

Response by poster: That, and rolling around in the dirt.

HA!

Not all of our cats like to roll in the dirt. (We have one, in particular, that is too fastidious to ever consider such an action.)

We once had a cat, though, who loved the dirt. Tintin was all white, from head to toe, absolutely gorgeous. His favorite activity during the summer was to roll in the flower beds. And the driveway. And the vegetable garden. He'd roll and roll and roll until his pure white coat became a dark and dusty brown. Then he'd try to come sit on us. And, later, when the sun had gone down, Tintin would spend hours licking himself clean. I think that he rolled in the dirt just so he could clean himself later.

On an only semi-related note, our newest cat (the fastidious one) has taken to licking my beard at night when I'm asleep. I'll be dreaming geek dreams when suddenly I'm awakened by this raspy cat tongue ripping through my facial hair and, worse, by the stench of cat breath.

Ugh.
posted by jdroth at 11:37 AM on March 5, 2004

On an only semi-related note, our newest cat (the fastidious one) has taken to licking my beard at night when I'm asleep.

He likes you! He really, really likes you! (wipes tears from eyes). Seriously, he's probably bonded to you. I'll bet you can't take two steps without him being underfoot right?
posted by bonehead at 1:46 PM on March 5, 2004

The notion of why cats eat grass was explained to me that their prey are vegetarian. They tend to eat the stomach (and its contents) of their prey first. This gives them their 'salad'.

Get them some kitty grass. Consider buying untreated sprouting wheat from a healthfood store as this is surely cheaper than packaged petcare products. When I last bought cat grass (years ago) it was wheat they used.

If hairballs are an issue, look for a product called Petromalt. Its vaseline with flavoring and vitamins, designed to make the hairballs slide through the system.
posted by Goofyy at 10:57 PM on March 5, 2004

but Science Diet is awful crap, while Prescription Diet is manufactured with a lot more care

wow. sketchy link.

don't old/poor folks eat pet food, every once in awhile?

or is that just an urban myth?
posted by fishfucker at 4:26 AM on March 6, 2004

sketchy link

Just happened to be the first one I came across. See also here, and for comparisons and specific ingredient analysis see here. They have supposedly improved their handling and sources recently, but I personally will never feed it again, the ingredients are too poor and there are far better foods on the market. But of course, do your own research and make up your own mind.
posted by biscotti at 11:10 AM on March 6, 2004