Why do Dogs and Cats Eat Grass?

You feed your pets a well balanced diet, they eat well, and they aren’t vomiting on the regular or having significant diarrhea….so why the heck are they eating grass? Not to mention the fact your cat is a carnivore and you’ve now had to put every house plant out of reach. What’s going on?!?!

As it turns out eating grass and other plants isn’t that abnormal a behavior for dogs or cats. Wild dogs and cats tend to eat every piece of an animal they kill, including their intestinal tract. Most of their prey consists of herbivores (think wildebeest, deer, mice, rabbits, etc.). Also, it’s been documented many times that wild dogs and cats will intentionally chew on grass and wild dogs have even been observed eating berries, fruits, and other vegetation. That’s because technically dogs are what we call opportunistic scavengers, meaning they eat what they can get ahold of for nutrients. This doesn’t really help us with our carnivorous cat friends though, so what’s up?

In short...we don’t really know. There are a bunch of theories out there, but until Dr. Doolittle actually exists we’ll have to just hypothesize and wonder. So if you’re satisfied with that answer or are looking for a hard and fast rule I guess stop reading now; however, there are a lot of theories which could explain why our furry friends are grazing grass.

Upset Stomach?

One of the most common theories floating around pet owners is that dogs and cats eat grass because their stomach hurts. This is certainly possible for some, but is definitely not why all dogs and cats eat grass. Grass is not fully digestible by cats or dogs, so if they do eat a lot of grass quickly it’s likely they will then vomit it right back up. So, if your pet doesn’t usually eat grass, then randomly starts inhaling it and vomiting soon after then it is likely your particular furry family member has a stomach ache and it’s time for a trip to the vet.

However, it’s more often that cats and dogs eat grass and don’t vomit. In fact one study of owners found that fewer than 10% of dogs showed any signs of illness before eating grass and less than 25% vomited regularly after eating grass. Cats are routinely found nibbling on your favorite houseplant and no vomit is found. So why else would they be doing this?

Fiber?

Again, grass and plant matter are not easily digested by cats or dogs. So, if they eat plant material and don’t vomit it makes sense it would then pass on through the intestines without being broken down. This can help relieve mild constipation and in cats can help move hair along the GI tract. Many cats experience hairballs on ocassion and grass can help bring them up or move the hair that wasn’t vomited along and come out the other end. There is one report of a poodle who was noted to eat grass almost daily and vomit. The owner switched the dog to a higher fiber diet and it immediately stopped.

Nutrients?

Some plants (especially grass) contain quite a bit of folic acid. This is a nutrient often found in a mother’s milk and helps improve the production of hemoglobin and growth. Hemoglobin is a key part of red blood cells which allows them to carry oxygen around the body. It’s theorized that especially in cats they may eat fibers of grass to get more folic acid helping with their circulatory system and growth.

Anxiety/Boredom?

Many dogs and cats will turn toward odd behaviors if they are stressed or bored. Some dogs will lick at a particular spot or have various OCD behaviors, and some will eat plants/grass. Cats will over-groom a particular area causing a loss of fur, may be more to themselves, or even get aggressive when stress. They can also turn toward eating and chewing on abnormal things (a behavior called pica). If your pet is showing other signs of stress or boredom, make sure your engaging with them each day. Make sure they’re active and have something to stimulate their mind. Use toys, have them scavenge for food, take them on walks, etc. If you’re still having issues with stress then it may be time to talk to your vet about environmental changes you can make. I really like pheromone diffusers for cats called Feliway to help reduce their anxiety.

Taste?

It’s a simple and boring excuse, but maybe some dogs and cats just like the taste, or even the “mouthfeel” if you will. There are plenty of cats and dogs who get a well-balanced diet, have no GI issues, and aren’t bored; yet they still turn toward the green stuff on occasion. I have one cat who loves to chew on any kind of plant and grass. I’ve looked at his diet: plenty of folic acid. I’ve made sure he’s not bored (he loves chasing my dog around the house). He doesn’t have an issue with hairballs and his food has a good percentage of fiber, but he still chews on grass. I have no idea what it is, but I really think he just likes the taste or feel of it. He’s not allowed outside, but he will dash out of the door on occasion when I let the dog out. He runs to the first spot of grass, stops, and starts munching...it does make it easy to catch him though!

So, who knows exactly why cats and dogs eat plants and grass. The follow up question would be:

Is it harmful?

Eating grass and plants in general isn’t going to cause any major problems, beyond vomiting as we previously discussed. However, there are certain situations in which plants can cause some major problems in our cats and dogs.

I’ve had several appointments over the years where an owner brings their dog in a couple of times a year for vomiting and GI upset. We take a look at the dog, maybe run some blood work to ensure it isn’t a major issue. Then we take a look at what may have changed in the dog’s routine or environment: any new treats, new food, new pets, changes in the home, etc. There have been a few times where the vomiting was seasonal and it was around the time landscapers and homeowners are using fertilizer or weed-killer on their lawns. So make sure your cat and dog aren’t eating grass with any kind of fertilizer, herbicide, or fungicide!

Also, there is quite the long list of houseplants which are toxic to cats. Most harmful plants cause kidney disease, but some can cause immediate and serious complications. The best resource to check if your plants are safe is the ASPCA Poisonous Plant List (https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants).

If your cat or dog loves chewing on grass there is a product called “cat grass” you can find at various pet stores and online. It is usually a type of wheat or oat grass your pet can munch on without you having to worry about toxins. It can be a way to allow your pet to safely graze away. Also for cats you can grow fresh catnip which is safe for cats to consume.

While we don’t know exactly why dogs and cats like to chew on grass and plants, hopefully this gave you some good theories and at least served to help you decide if it’s a problem for your dog or cat. Again, don’t forget to check the ASPCA Poisonous Plant list to determine if your houseplants are harmful for your furry friends!