It can be alarming to see your dog poop out bright green stool. Your dog’s poop may be different colors from time to time, and the specific color can give you a clue as to what is going on inside your pup. Green dog poop is something you shouldn’t ignore. Although it can be innocuous, it may also be a sign that something is seriously wrong with your dog’s health.

A blonde woman picking up dog poop.
Does green dog poop always require a trip to the vet? Photography ©AndreyPopov | iStock / Getty Images Plus.

Why do dogs poop green? Sometimes, it is nothing to worry about.  

When it comes to green dog poop — “It really comes down to two things,” says Tracey Jensen, DVM, Dipl. ABVP, medical director at Wellington Veterinary Hospital in Wellington, Colorado. “The first is that the green color is pigment that’s passing through the intestinal tract relatively unchanged. Chlorophyll is one pigment that can, in high enough volume, pass through and give green color to the feces.”

So, green pigment in the stool is not always cause for concern. If your dog eats a large amount of grass or other plant material, it could tint his poop green. Dr. Jensen has also heard of cases occurring after dogs eat a large number of Greenies treats. I personally have witnessed my dog poop a veritable rainbow of colors after stealing and eating my son’s Crayons. (It’s a good thing they are nontoxic because Crayons are like doggie crack to him!).

Man picking up dog poop.
Dog green poop can be a symptom of something very serious. Photography by By Monika Wisniewska / Shutterstock.

But sometimes it is a sign of something serious.

A scarier situation is if the green pigment is present due to your dog ingesting certain toxins. “A very dangerous pigment that can pass through is the pigment that’s used in rodenticides,” Dr. Jensen explains. Rodenticide (rat poison) can contain blue pigments as well as green.

If your dog has not ingested a pigment that is tinting his poop green, then the poop might indicate a health problem. “The second reason that feces will be green is because of altered absorption in the intestinal tract,” Dr. Jensen explains. “There’s a very important digestive juice called bile that has pigment to it. That pigment is usually resorbed, mostly in the colon, and recycled and reused. Sometimes with colitis — inflammation in the intestinal tract — the pigment will not be resorbed and it will pass through in the feces.”

A small dog about to poop, potty training with a roll of toilet paper.
You should always talk to your vet about green dog poop. Photography ©cynoclub | Thinkstock.

How do you tell the difference between the two types of green dog poop?

How can you tell if green dog poop is because your pup just ate some grass … or if he’s actually sick? “Many times, if the feces are altered in shape or if they’re mucousy, then the green you’re seeing is because the bile pigments aren’t being resorbed,” Dr. Jensen says. “If the feces are normal in shape and [show] consistency with green, then it very well could be that it’s something passing through the intestinal tract and not because of intestinal disease.”

Either way, place a call to your vet when you notice green dog poop. It’s hard to know if it’s green because your dog ate too much grass or because he ingested rodenticide. Bring a fresh sample so the vet can inspect and possibly test the green dog poop. If it’s poison, time is of the essence. The faster you seek veterinary care, the more likely it is that your dog will recover. Also, even if your dog just ate some grass, other complications can occur.

“Sometimes, dogs eating a large amount of grass is actually a symptom of gastrointestinal upset,” Dr. Jensen advises. “I had one [dog] who ended up obstructed after eating a lot of grass — some dogs simply do that because they like grass — so it’s always a good idea to give a call in.”

Thumbnail: Photography by By Paul S. Wolf / Shutterstock.

This piece was originally published in 2018. 

Read more about dog poop on