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Why Do Dogs Eat Grass?

Dogs eat grass for a variety of reasons.

Have you ever witnessed your dog chowing down on portions of pasture and wondered: why do dogs eat grass? It's an extremely common question, but the answer isn't as cut-and-dried as your lawn clippings are.

Are Dogs Carnivores or Omnivores?

People have believed for many years that dogs are omnivores, requiring both meat and plants for proper health. However, this basic notion has been challenged recently, and there are scientists who are convinced that wolves are carnivores like cats rather than omnivores like humans.

Even so, there are some genes that have been discovered in domestic dogs that indicate a bit of a shift toward the ability to digest more plant material than their wolf relatives can. However, dogs are still more highly-designed to be carnivores than omnivores.

So why do they munch on grass?

Do Dogs Eat Grass Because They Are Nauseous?

Probably the most common explanation that people accept for why dogs eat grass is that they are nauseous, and eating grass helps them vomit and feel better. It is true that dogs sometimes vomit after they eat grass. It's also true that you will see some dogs acting panicked, looking upset, and trying frantically to get outside, where they manically chow down on large mouthfuls of grass, then vomit. After that, they look more comfortable. However, research has shown that neither scenario is particularly common (Karen Lynn Chieko Sueda, 2007). So, while nausea may account for a small percentage of grass-eating episodes, it doesn't seem to explain all of them.

Is Canine Grass-Eating Caused by Missing Nutrients?

Another popular hypothesis is that dogs seek out and eat grass if they are missing something in their regular diet. Research has not borne this out as a particularly plausible cause, either. In fact, one study showed that dogs with diets that were supplemented with vegetables and fruits ate grass at the same rate as those with diets that weren't supplemented with those items. This indicates that nutritional value is not likely to be the cause of grass-eating behavior in dogs.

The same study found that dogs ate more grass before they were fed their regular morning kibble than at any other time, demonstrating that they might just be hungry and see the grass as a food source (S.J. Bjone, 2007).

Does Eating Grass Clear out Intestinal Parasites?

Grass helps wolves clear large intestinal parasites such as roundworms out of their stomachs. The grass causes increased small intestinal motility and can also physically wrap around the worms and carry them out. Although many domestic dogs are parasite-free, their grass-eating habit may be a residual evolutionary urge to clean their systems of intestinal worms.

Is It Because Wolves Eat The Stomach Contents of Their Prey?

Another logical explanation for many dogs' propensity for eating grass is that their wild relatives and ancestors, the wolves, eat the stomach contents of their prey. Because their prey are herbivores with stomachs full of plant material, wolves' diets end up including some grass. Research on the droppings of wolves does find a certain degree of plant material present, indicating that wolves do sometimes ingest grass somehow. This seems to be one plausible reason why domestic dogs eat grass: it's an ingrained habit.

So Why Do Dogs Eat Grass?

As is the case with so many canine behavior questions, it isn't 100% clear why dogs eat grass, and there may be multiple reasons. One reasonable answer is that they like it. One study found that puppies eat grass more commonly than older dogs, indicating that there may be a playful aspect to the blade-chomping, as well. Puppies like to put everything in their mouths, and grass is no exception. They may find out that the taste and texture are pleasant and carry the habit through their lifetime.

So, while there may not be one specific reason for dogs to eat grass, research indicates that it is a normal thing for them to do (Karen Lynn Chieko Sueda, 2007).

Is Eating Grass Dangerous for My Dog?

Your dog's grass-eating habit is not likely to cause him any issues except in the following instances:

  • Grass that is treated with fertilizers or insecticides may be harmful to dogs that ingest it.
  • Dogs that are having a medical issue that causes vomiting may aggravate the problem by eating grass and mechanically irritating an already inflamed stomach lining. This may perpetuate the vomiting when it may otherwise resolve. If your dog is being treated for vomiting, keep him on a leash when you take him outside to deter him from eating grass.

You may consider growing some grass indoors to satisfy your dog's desire to munch. This will ensure that he's eating chemical-free grass, and it may curb his craving for the outdoor variety. You can also consider giving him wheatgrass, which may have some health benefits beyond satisfying his desire to chew on grass. Learn more about feeding wheatgrass to dogs in the article "Wheatgrass for Dogs."

Works Cited

  1. Karen Lynn Chieko Sueda, B. L. (2007, May 24). Retrieved from Applied Animal Behavior Science: http://www.appliedanimalbehaviour.com /article/S0168-1591(07)00182-7/abstract
  2. S.J. Bjone, W. B. (2007). Grass eating patterns in the domestic dog. Retrieved from une.edu: http://www.une.edu.au/__data/assets/pdf_file/ 0019/32446/bjone-brown-price-grass-eating 20patterns-raan-2007.pdf

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