Why do cats eat grass?
The reason why cats sometimes eat grass (and other plants) is not completely understood. There are several plausible theories as to why they do this.
For the nutrients:
As we know, cats are carnivorous, they need to consume meat to survive. Dogs and humans can get by without meat. However, when cats hunt, they consume almost all parts of their prey including the stomach and the contents of the stomach. This may include small amounts of plant matter and the nutrients within them. A cat living with humans doesn't (and shouldn't) hunt and therefore won't get to ingest those small amounts of plant material from the stomach of their prey and therefore may try to obtain these vitamins/minerals by eating grass if there is a nutritional imbalance in the diet.
To help them vomit:
We all know what happens after our cats consume grass, they come back inside and vomit all over our favourite rug/sofa/bed etc. It's almost as if they are doing it to spite us. This is not the case! It is believed that grass acts as an irritant to the stomach, and cats don't have the ability to digest grass in the way herbivores do and eating grass results in vomiting. This makes sense from an evolutionary point of view because when hunting, cats eat their prey, they eat the whole thing, feathers, bones and other indigestible parts. Vomiting helps rid the digestive tract of these unwanted products.
I don't know if this theory holds true or not, but I wonder if vomiting also helps to lighten the load of parasitic worms in the stomach? I will have to look into that further.
To bring up hairballs:
Adding to the vomiting theory, it is speculated that another reason cats consume grass is to assist with the passage of hairballs. When cats groom themselves, they inevitably ingest fur which can build up in the stomach. Eating grass can help with the passage of hairballs either from vomiting or as a laxative.
Because they can:
It may really be as simple as that. They enjoy the taste of grass. Having spoken to many cat loving friends, it is no longer a surprise to hear of cats eating other types of greenery such as cucumber and broccoli. Read more on human foods cats can eat here.
What kind of grass:
If you want to grow a tub of grass inside for your cat to nibble on, common types include:
Is there a difference between cat grass and catnip?
Yes, catnip is a member of the mint family. They are completely unrelated. Catnip can also induce a high in some cats, however cat grass doesn't have this effect on cats.
Both cat grass and catnip are perfectly safe for your cat to eat but do bear in mind there are a large number of plants that are toxic to cats. It is recommended you don't have indoor house plants that are poisonous as they can in some cases lead to death. Click here for a list of plants toxic to cats.
It should also be mentioned that grass grown outdoors may have been sprayed with chemicals such as weedkillers or fertilisers that can be toxic to cats, so if you have an outdoor cat, caution should be used if your cat has a tendency to nibble on the greenery.