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Why dogs eat grass and dirt

Why do dogs eat grass and dirt? And the science of Zoopharmacognosy!

A lot of dogs eat grass. Sometimes it’s a bad thing, but other times it’s just normal.

Sometimes, you’ll also find your dog eating dirt.

So let’s take a look at the ins and outs of why dogs eat grass and dirt, including the science behind it!

Why do dogs eat grass?

Some reasons why dogs eat grass, in a nutshell:

  • Because they feel sick and it helps them vomit.
  • Because their instincts are telling them it has nutrition or can act as a herbal medicine.
  • Because they’re just a little weird, and they happen to like it.

Okay, take that last one with a pinch of salt. Of course our dogs aren’t weird!

Did you know dogs lack the enzymes to digest grass, so there’s actually no nutritional value to them in eating it?

Not that we know of, anyway.

Your dog will either eat grass then regurgitate it, which suggests they’re feeling unwell (something they’ve eaten?), or they’ll let the grass work it’s way through their system.

Why dogs eat grass Australia

Other animals eat grass and plants when they have gut parasites, such as worms, so keep that in mind – more on that later.

There’s a lot of debate why dogs eat grass and let it digest, but the science world is starting to conclude it’s almost certainly as a herbal medicine.

If we look at the way some other animals treat certain plants in their environments, we start to see a picture of animals self-medicating from eating grass, and our dogs may share this same trait.

This phenomenon of using grass to self-medicate is called Zoopharmacognosy, and it’s a fairly new discipline of science.

The purpose of Zoopharmacognosy is researching how animals use plants, soils, insects, and psychoactive drugs as medicine, and also if whether there are any benefits or implications for not only animals, but also us humans!

Why do dogs eat dirt?

It’s less common for our dogs to eat dirt, but they do so for very similar reasons as grass.

If your dog’s eating dirt to promote vomiting, such as when they don’t have access to grass, then you should consider the underlying reason why – is it a health concern, or possibly a reaction to something they’ve eaten?

Some dogs, surprisingly, enjoy the taste of dirt. It sounds strange to us as we were taught at a young age dirt was, well, dirty.

Dirt may also be a source of minerals, which your dog instinctively knows can be sourced from the dirt.

This may be the result of a poor diet (what’s in your dog food?), which is causing your dog to go out and find nutrition from elsewhere. Dirt is therefore an option.

Perhaps Zoopharmacognosy (which I’d really love to rebrand as ZPC or something simpler) will help us learn more about why dogs eat dirt in the future!

How Zoopharmacognosy helps us understand why our pets eat grass and dirt

Please note I’m not a Zoopharmacognosyacologist, but I’ll skirt over some really interesting aspects of the subject.

After all, they provide some insight into why our dogs eat grass and dirt!

Why do dogs eat grass and vomit?

Getting rid of parasites

Some ape species eat grass and dirt when they have gut parasites (such as worms). They tend to favour certain rough-leaved plants which effectively help them clear out these internal parasites.

For our dogs we have medicines and worming treatments, but it’s possible our dogs will eat grass to cope with those issues with grass if medication isn’t provided.

Therefore we should consider parasites as a potential cause of our dog’s eating grass, and consider if they have been wormed recently.

“Scooting”, which is when your dog wipes his bum along the floor, is another sign of parasites to look out for. It can also be an anal sac issue.

Many suggestions about our dog’s eating grass centre around gastrointestinal issues.

Perhaps dogs know to eat grass when they have a tummy upset, to help settle their stomach, or because they’re instinctively treating a condition with grass as a herbal medicine.

Butts in the nest

This isn’t really about dogs, but it’s an interesting topic I encountered while researching Zoopharmacognosy (on the Internet, not at University).

Scientists have seen some urban birds incorporate cigarette butts into their nests, which originally seemed like bizarre behaviour.

It’s now more understood those birds use the residual nicotine as a deterrent for certain parasites. How crazy and smart is that?

Scientists have even discovered certain insects – such as moths and caterpillars – also turn to our natural environment, grass, dirt, and even toxins, to use as herbal medicine.

Because of these scientific findings, it’s much easier to understand our dogs use grass and dirt as a herbal medicine.

The right dose

It seems the animal kingdom doesn’t only know which plants to use for which conditions, but they are also clever enough not to over-dose themselves.

Many plants can be toxic in large doses, while their medicinal properties are most effective at a certain amount.

How do the animals know this – whether they learn it from each other, passing the knowledge down from generation to generation, or experiment with it themselves?

Or, in the case of insects, whether it’s an instinct – scientists are yet to fully explore.

At the moment, with the research available to us, we can merely assume our dogs and cats use grass and dirt because they instinctively know it will help them, whether it’s parasites, sickness, or a gastrointestinal issue.

What we can also assume is this – animals have been “studying medicine” for as long as the human race, perhaps longer!

Let’s hope useful insights from Zoopharmacognosy can further aid the health of our pets, and also our own health.

Common questions about why dogs eat grass and dirt

Just for completeness, I’ll cover some of the common questions about why dogs eat grass, like a little FAQ:

Why do dogs eat grass and then vomit?

If your dog feels sick or has gastrointestinal pain, eating grass can help them regurgitate to lessen discomfort. Usually your dog will erratically eat grass, attempting to consume as much as possible to prompt the vomit.

Why do dogs eat grass when their stomach is upset?

A dog will instinctively eat grass to promote vomiting when they have an upset stomach or gastrointestinal discomfort.

Is it bad for dogs to eat grass?

Grass is harmless to a dog but if they are eating it to vomit it can suggest an underlying issue. As a dog owner you must be wary of pesticides or weed killers used on grass, as this can be carcinogenic.

The science of Zoopharmacognosy has found evidence animals additionally consume grass as a herbal medicine.

Why does my dog eat grass every day?

Some dogs enjoy the taste of grass, but as they also instinctively seek out nutrients we must consider if their diet is lacking in nutrition.

Why do dogs eat grass in hot weather?

Grass has a high moisture content, which may help your dog stay hydrated in hot weather. It may also help your dog regulate their body temperature.

Dogs pant to evaporate fluids from their tongue and respiratory system, which speeds up heat loss. By eating grass, they may be able to increase the evaporation rate and cool off more quickly.


Did that help you understand why dogs eat grass and dirt? Or do you have anything else to add?

Comments welcome!

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