If your dog is suddenly munching on large amounts of grass and then throwing up, you’re likely wondering what’s going on.
While eating grass is not unusual for dogs, dog eating a lot of grass and throwing up can signal something more serious.
We outline the reasons behind this behavior, what it might mean for your dog’s health, and when it’s time to call the vet.
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Here’s Why Your Dog Is Eating a Lot of Grass and Throwing Up
When a dog is eating a lot of grass and throwing up, it’s often a sign of gastrointestinal discomfort or an attempt to self-soothe an upset stomach.
Dogs may instinctively eat grass to induce vomiting, which can help expel something irritating in their digestive tract.
While occasional grass eating followed by mild vomiting is usually not a cause for concern, frequent or excessive grass consumption combined with repeated vomiting can indicate underlying issues such as gastritis, intestinal parasites, dietary intolerance, or even anxiety.
Why Do Dogs Eat Grass?
There are several reasons why dogs eat grass. While not all of them are harmful, understanding the possible causes can help you determine if your dog needs veterinary care.
1. Gastrointestinal Upset
One of the most common reasons for dog eating a lot of grass and throwing up is digestive discomfort.
Dogs may instinctively eat grass to induce vomiting when they feel nauseous, bloated, or have an upset stomach.
The grass can irritate the stomach lining, which in turn causes them to throw up, possibly providing temporary relief.
Signs of digestive upset include:
Lethargy
Drooling
Gurgling stomach sounds
Loss of appetite
Diarrhea
If your dog vomits once after eating grass and seems fine afterward, it may not be serious.
But if the vomiting continues, it could indicate a deeper issue like gastritis or infection.
Related: Dog eating grass and dirt (Here’s why)
2. Dietary Deficiencies
A dog eating a lot of grass and throwing up may be trying to compensate for missing nutrients, particularly fiber.
Grass contains small amounts of fiber, which may help with digestion or bowel movements.
Dogs on low-fiber diets or commercial foods lacking in roughage may seek out grass as a natural supplement.
If this is the case, switching to a high-fiber dog food or adding vet-approved veggies like pumpkin or green beans may help reduce the behavior.
3. Parasites and Infections
Internal parasites like roundworms, hookworms, or Giardia can cause gastrointestinal upset, leading your dog to eat grass in an attempt to relieve discomfort.
Bacterial and viral infections can also irritate the digestive tract and result in vomiting.
If your dog eats grass frequently and vomits, and you notice symptoms like diarrhea, weight loss, or poor coat condition, consult your vet for a stool test and possible treatment.
4. Boredom or Stress
Sometimes, a dog eating a lot of grass and throwing up isn’t about their stomach—it’s about their mind.
Dogs may resort to compulsive grass eating when they’re anxious, bored, or experiencing a change in routine.
Common triggers include:
Being left alone for long periods
Loud noises (e.g., thunderstorms)
Moving homes
New pets or people in the house
In these cases, behavioral enrichment and stress relief can reduce grass eating.
Try puzzle toys, regular exercise, or calming treats to manage anxiety.
Related: Does eating grass make dogs sick?
5. Toxin Exposure
If your dog is eating a lot of grass and vomiting repeatedly, consider the possibility of toxic substances.
Lawns treated with pesticides, herbicides, or fertilizers can cause poisoning.
Toxic grass ingestion may result in:
Excessive vomiting
Drooling
Seizures
Diarrhea
Lethargy
If you suspect your dog ate chemically treated grass, go to the vet immediately. Bring information about the product used, if possible.
Medical Conditions Linked to Grass-Eating and Vomiting
Several medical conditions may explain why your dog eats a lot of grass and throws up:
Gastritis
Inflammation of the stomach lining can cause nausea and vomiting. Dogs may instinctively eat grass to vomit and get relief.
Acid Reflux
Dogs with acid reflux may eat grass to neutralize stomach acid.
This may help them feel better temporarily, but it doesn’t treat the root cause.
Inflammatory Bowel Disease (IBD)
Chronic vomiting and diarrhea, along with grass-eating behavior, can signal IBD.
This condition involves inflammation of the digestive tract and needs a veterinary diagnosis and long-term management.
Pancreatitis
Sudden vomiting, especially after eating, could point to pancreatitis—a painful and potentially life-threatening condition.
Dogs may eat grass in response to nausea before vomiting.
How to Help a Dog That’s Eating Grass and Throwing Up
If you notice your dog eating grass and throwing up, take these steps to evaluate and address the issue:
1. Observe Closely
Keep a journal of when your dog eats grass, how much, and what happens afterward.
Note symptoms like vomiting, diarrhea, or lethargy. This information will be invaluable for your vet.
2. Check for Access to Toxins
Make sure your lawn and garden are free from pesticides, fertilizers, and toxic plants.
Avoid letting your dog graze in areas that may be chemically treated.
3. Adjust Their Diet
Talk to your vet about switching to a high-quality dog food with appropriate fiber content.
Consider adding natural fiber sources such as canned pumpkin or cooked sweet potato to aid digestion.
4. Deworm and Test for Parasites
Have your dog tested for parasites regularly, especially if they’re showing signs like vomiting and weight loss.
Deworming schedules should be maintained per your vet’s advice.
5. Provide Mental and Physical Stimulation
Boredom and anxiety can trigger compulsive behaviors.
Enrich your dog’s life with interactive toys, regular walks, socialization, and playtime.
Dog Throwing Up After Eating Grass: When to Be Concerned
While occasional grass-eating followed by vomiting isn’t always an emergency, frequent episodes or accompanying symptoms can point to a serious issue.
If you notice your dog eating a lot of grass and throwing up regularly, watch for the following warning signs:
Persistent vomiting (more than 24 hours)
Vomit containing blood or bile
Diarrhea or bloody stools
Loss of appetite
Dehydration (sunken eyes, dry gums)
Weakness or lethargy
In such cases, your dog may be suffering from a more severe gastrointestinal condition, such as pancreatitis, inflammatory bowel disease (IBD), or even a blockage.
When to See the Vet
Contact your veterinarian immediately if your dog eats grass and throws up frequently, or if the vomiting is accompanied by other symptoms such as:
Diarrhea
Weakness
Refusing to eat or drink
Repeated or projectile vomiting
Signs of abdominal pain
Puppies, senior dogs, and dogs with pre-existing health conditions are especially vulnerable and should not be left untreated.
Final Thoughts
While occasional grass nibbling may be nothing to worry about, a dog eating a lot of grass and throwing up frequently may be a sign of an underlying issue.
Whether it’s digestive discomfort, nutrient deficiencies, stress, or something more serious like infection or poisoning, it’s important to address the cause.
By observing your dog’s behavior, adjusting their diet, and consulting with your veterinarian, you can help your dog feel better and prevent future episodes.
Always err on the side of caution and seek professional help when symptoms persist.