Why do cats eat grass and throw up?

There may not seem to be much for you to be happy about when you discover a pile of cat vomit on your carpet. However, if your feline has emptied his or her stomach after gnawing on some plant matter, it could actually be good news. How so?

Meet Bagel

Bagel came into our lives one cold, winter night when Max, my 9-year-old son, heard meowing from somewhere in the alley near our apartment building. At his urging, we investigated the area and discovered a box of kittens left behind a bakery.

Of course, we had to take them home. Fortunately, with the help of our neighbors and a local cat rescue team, each of them soon found loving fur-ever homes… with the exception of the runt of the litter, barely bigger than a bagel curled up on Max's hand. When I saw how they'd bonded, though, I knew this little guy had found his home, too.

For the next six weeks we bottle fed Bagel, but soon he started throwing up his milk. A cat shelter volunteer informed us that 6 weeks was too old for milk, and Bagel was ready to begin eating solid foods.

We started him on wet canned food. He often preferred playing in the food as opposed to eating it. He eventually got the hang of it, but every now and again he'd vomit. Perhaps he was eating too fast or too much? Worried he had picked up a parasite in the alley, we took him to the vet, but she assured us he that he was fine.

The vet told us that the main things to watch out for if you have a chronic puker are that the cat doesn't get dehydrated and doesn't lose weight. If he is dehydrated, starts losing weight, becomes really lethargic, or stops eating altogether, you need to get him to a vet as soon as possible. 

This is especially the case with kittens, which go downhill very fast under these conditions, so time is of the essence if any of this happens with them. But Bagel was playful and gaining weight every day, so we were relieved to hear this.

Not all members of our family were healthy, though. I started to notice that “Spidey” the spider plant was gradually looking a thinner and scrappier. Then one morning I heard Max loudly announce, “Eww!”

He had stepped barefoot in a pile of goopy, brown cat bile with a few chewed-up spears of spider plant mixed in. Bagel hadn't barfed since his transition from bottle-feeding to solid foods, so I again worried that he was seriously ill. I was also worried that houseplants might not be good for him. 

Again, the vet assured me there was nothing to worry about. I did some more research and was relieved to find that my spider plant is on the list of safe plants for cats. Here is a list of safe plants to keep in your home. Some light munching on these will cause no harm:

  • Spider Plant
  • Wandering Jew
  • Christmas cactus
  • check
    Bromeliads

However, certain houseplants are bad, even toxic for your cat. Here is a list of the most dangerous plants. Basically lilies are OUT. True lilies of the Lilium or Hemerocallis species are very toxic. Examples of some of these lilies include the following:

  • Tiger lillies
  • Day lillies
  • Asiatic hybrid lillies
  • ban
    Japanese show lillies
  • ban
    Easter Lillies
  • ban
    Rubrum Lillies
  • ban
    Stargazer lilies
  • ban
    Red lilies
  • ban
    Western lillies
  • ban
    Wood Lillies

Poinsettia plants, a favorite holiday plant for many people, are not deadly; but they are toxic enough to make your cat mildly sick. While poinsettias are in a group of toxic plants, they are only mildly poisonous to humans and animals. 

The white sap in the plant can cause skin or digestive irritation, but it would have to be consumed in large quantities to be deadly. The bad flavor should naturally deter your puss from contemplating a major chow-down, but it’s still worth taking precautions to keep these plants away from your cat.

Meanwhile, Spidey was seriously starting to look worse for wear, so when Max spotted some “cat grass” at our local pet store, I decided to give it a try. Not only is there no evidence to suggest that grass will harm your cat, but many experts theorize light grazing on an indoor patch of lawn can actually be beneficial.

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But why do cats eat grass and throw up?

Cats barf when they eat grass because they lack the necessary enzymes to break down vegetable matter. Does this mean your cat is seeking out the opportunity to upchuck? While it's doubtful that kitty enjoys the act, the process does eliminate all indigestible matter from the cat's digestive tract, making it feel a whole lot better.

 

This is especially important for outdoor cats, because all cats eat their prey as-is, including both the edible and inedible parts (fur, bones, feathers, and so on). Bagel only has toy mice and birds, but just in case we get a mouse in the house and he decides to get in touch with his primal side, it's good to know we have grass as an option for his after-dinner treat.

Much like mother's milk (or in Bagel's case, bottled kitten formula), the juices in grass contain folic acid. This is an essential vitamin for a cat's bodily functions and assists in the production of hemoglobin, the protein that moves oxygen in the blood.

Grass can also act as a natural laxative, in case your fur baby is feeling a little backed up, and not just from too much tuna. All of that coat licking adds up, and when fur moves deep into the digestive tract, kitty needs a little help to break it down and pass it out one end or the other.

Another option for helping Fluffy break up and release those hairballs is a petroleum-based gel (usually fish flavor) you can buy at the pet store. A dime-sized squeeze into his food or rubbed directly onto his coat will do the trick. 

You may also want to buy a small tray of grass just for the cat. If you are a DIY kind of cat parent, you could curate a potted plant of grass for your cat. This way you also won't have to worry about accidental ingestion of pesticides, herbicides, or chemicals that may have been used to treat a lawn.


You could even consider starting a cat-friendly herb garden. In addition to catnip, a few other safe herbs popular with felines are basil, oregano, chamomile, and lavender.


All in all, ingesting grass is not a bad thing. Some even believe cats eat grass to relieve sore throats. However, whether you have an indoor or an outdoor cat, you should make sure that all your household plants are of the non-toxic variety.