Why Dogs Eat Grass (and Why Some Dogs Throw Up Yellow Bile)

Why do dogs eat grass and vomit yellow bile?

Because the gut, nervous system, and musculoskeletal system are trying to self-regulate.

Grass eating in dogs is rarely just a stomach issue — it’s often a sign that the nervous system, digestion, and body tension are trying to rebalance together.

Nate, a gorgeous senior Aussie-Greyhound mix, pauses to eat some wild grass during a forest walk - a common instinctive behaviour often linked to digestion, nervous system regulation or eating a high fat treat on an empty stomach.

It’s not bad behaviour. It’s communication.

Dogs eating grass — especially followed by yellow, foamy bile — is one of the most common things guardians Google in a panic.

The good news? Most of the time, it’s normal, age-dependent, and very fixable.

The key is understanding why it happens at different life stages — and what the body is trying to regulate.

First: what does a dog eating grass usually mean?

Grass eating is not one single behaviour. It can signal:

• mild nausea

• stomach acid or bile irritation

• hunger or an empty stomach

• microbiome imbalance

• stress or nervous system dysregulation

• fascial and muscle tension in neck, spine or lower pelvis

• dietary mismatch

• learned self-soothing behaviour

In other words:

The gut and the nervous system are talking. Grass is the dog’s way of listening.

Puppies Eating Grass: Curiosity, Learning, and Their Immature Digestive System

Common reasons puppies eat grass:

• exploration (mouth-first learning)

• teething discomfort

• immature digestive enzymes

• gut bacteria still stabilizing

• eating too fast or irregular meals

What helps:

• smaller, more frequent meals

• slow feeders

• consistent probiotics (canine-specific)

• limiting random treats

• redirecting grazing into sniffing instead

Most puppies outgrow grass eating as their digestion matures.

Adult Dogs Eating Grass: Regulation, Stress, and Diet Balance

In adult dogs, grass eating is more intentional.

Common triggers:

• mild nausea from bile buildup

• skipped meals or long gaps between meals

• rich treats on an empty stomach

• food sensitivities stacking over time

• stress (environmental or emotional)

• intense exercise without fuel

Why Some Dogs Throw Up Yellow Bile

Yellow bile vomit usually means:

• the stomach was empty

• bile irritated the stomach lining

• grass triggered a purge

This is especially common in the morning.

What helps most adults:

• a small bedtime snack

• consistent feeding schedule

• limiting high-fat treats (ie. too much Himalayan cheese or bully sticks...sorry Fido!)

• single-source proteins both as treats and meals (ie. avoid the amazing sounding "surf & turf" mix that has 5 different protein sources and opt for single protein with appropriate veggies/supplements etc.)

• adding water or broth to meals

• probiotics given daily, not sporadically

Why Senior Dogs Eat Grass More Often

As dogs age, digestion becomes more delicate — even when bloodwork is “normal.”

Pre-senior and senior dogs - sensitivity increases:

• slower gut motility (aka "digestion")

• reduced microbiome diversity (hence the dire need of pre/probiotics more than ever)

• subtle liver or pancreas inefficiency

• pain or tension affecting the vagus nerve

• medication side effects (past or present)* And the usual medications that kill a dog's microbiome are antibiotics and standard NSAIDs. They can linger in a dog's system for months.

This is why senior dogs often regulate through the gut first.

What helps seniors most

• smaller, more frequent meals

• avoiding long fasting periods

• consistent probiotics + digestive enzymes

• gentle fibre (ie. pumpkin, greens and veggie mixes)

• hydration support

• nervous-system calming (routine, touch, predictability)

• a full manual lymphatic drainage done helps eliminate lingering side effects of medications (while not impacting their effectiveness)

Many senior dogs stop grass eating almost entirely once tension and pain are managed together with consistent use of probiotics and avoiding high-fat treats.

Is grass eating ever dangerous?

Rarely — but it can be if:

• grass is chemically treated

• your dog is chewing grass near a rat poison box where heavy rainfall leaches toxins into the surrounding grassy area

• vomiting is frequent or violent

• weight loss occurs

• appetite drops significantly

• stools turn black or tarry

If you see those signs → loop in your vet.

What NOT to do:

• Don’t punish grass eating

• Don’t drastically change their food overnight. Instead, if you need to make changes, do it progressively over a couple of weeks

• Don’t over-supplement randomly

• Don’t assume it’s “just behavioural”

The body is asking for help — not correction.

What actually helps stop grass eating (most of the time)

Top support Summary

1. Consistent meal timing

2. Bedtime snack for bile-prone dogs

3. Single-source treats only

4. Daily probiotics (low dose, consistent)

5. Adequate hydration

6. Reduced stress + predictable routines

7. Addressing pain or tension elsewhere in the body (neck, spine, ribs, below the pelvis)

When the nervous system settles, the gut usually follows.

Practitioner Insight:

In comprehensive bodywork sessions, I often see grass-eating dogs release tension in the ribs, diaphragm, lumbar spine, or iliopsoas — and their stomach symptoms quietly improve within days or in severe cases, weeks.

That’s not coincidence.

The gut, spine, and nervous system are inseparable (see below).

Grass isn’t the problem.

It’s the clue.

Why this usually isn’t “just a gut issue”

When dogs eat grass or vomit bile, the body is often trying to regulate more than digestion alone.

The vagus nerve — the only cranial nerve that travels like a Bedouin wanderer outside the brain, down the carotid sheath through the neck, through the lungs, around the heart, through the ribcage, passing the diaphragm, and into the abdominal fascia.

If tension, pain, stress, or compensation patterns are present anywhere along that pathway, digestion can become reactive.

That’s why some dogs improve only temporarily with food changes alone. The same is true in humans, although we don't forage for grass when digestion issues occur!

 

How Professional Bodywork Can Support a Dog with GI Upset Including Grass Eating

• reducing tension along the vagus nerve pathway through targeted neurovascular (vagus nerve) release

• specific massage techniques that reduce gas/bloating

• stimulating and activating the parasympathetic (“rest and digest”) nervous system

• improving rib, diaphragm, and spinal mobility

• easing compensatory muscle patterns that affect gut motility

• helping settle the nervous system so digestion can normalize

This is why grass eating often decreases when the whole body is supported. When we address those patterns through gentle, consent-based, multimodal bodywork (alongside appropriate veterinary care when appropriate) digestive symptoms frequently soften or resolve.

Digestive upset is often connected to stress patterns, abdominal tension, or spinal restriction. Curious if bodywork might help your dog and you live in the Vancouver & Lower Mainland area?

Request a free consultation or book a session for your dog.

Book a Free Consultation or Comprehensive Bodywork Session

Bodywork doesn’t replace veterinary care. It supports how the dog’s body lives inside that care. (See below for a list of complementary treatments/therapies as well as modern scientific & veterinary research that endorse multimodal treatments and therapies as the new standard of care for dog health and quality of life.

Key References

• Hart et al., Applied Animal Behaviour Science, 2019

• Sueda et al., Journal of Veterinary Behavior, 2008

• Schöberl et al., Frontiers in Veterinary Science, 2021

• Mills et al., Canine Stress and Behaviour, 2020

• National Research Council, Nutrient Requirements of Dogs, 2006

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Important Note on Modern Integrative Care:

• Canine bodywork is complementary to veterinary care — not a replacement.

• Veterinary medicine remains essential for diagnosis, imaging, pharmacologic treatment, and medical decision-making.

• Multimodal pain management (medication plus physical and supportive therapies) is now considered standard of care in veterinary medicine.

• Stress and nervous system state directly influence pain perception, gastrointestinal function, healing capacity, and behaviour.

• Physical rehabilitation and manual therapies, when applied appropriately and in collaboration with veterinary care, improve functional recovery, comfort, and movement efficiency.

Non-pharmacologic therapies/treatments include the following (not an exhaustive list):

• Canine rehabilitation and bodywork

• Guided therapeutic exercise

• Hydrotherapy

• Chiropractic & Acupuncture/Acupressure therapies

• Infrared / red light-based therapies

• Regenerative injection therapies (e.g., prolotherapy, platelet-rich plasma [PRP]) in appropriately selected cases (ie. ligament tears)

• Kinesiology taping (using animal-specific kinesiology tape - not human tape - they differ!)

All delivered alongside veterinary diagnosis and oversight.

Current scientific & veterinary evidence demonstrates that:

• Modern veterinary research and clinical guidelines support multimodal care — the combined use of pharmacologic and non-pharmacologic therapies and treatments — to improve outcomes in pain management, recovery, longevity and long-term quality of life.

• These approaches are most effective when delivered with a veterinarian who supports collaborative, integrative care.

• *Note: If a vet does not support evidence-informed complementary modalities, guardians may consider seeking a provider who values a team-based, whole-dog approach to long-term health and recovery.

• The most effective care models are collaborative — where veterinarians and qualified practitioners work together to support both the medical plan and how the dog lives, moves, and regulates within that plan.

  
  

Modern Scientific References Supporting Multimodal Collaborative Care:

• Re: Multimodal Pain Management as the Standard of Care: Mathews KA. et al., Journal of Small Animal Practice, WSAVA Global Pain Council Guidelines

• Stress, Nervous System Regulation & Physiology: Schöberl I. et al., Scientific Reports, and Pirrone F. et al., Animals

• Rehabilitation & Manual Therapies: Millis DL & Levine D, Canine Rehabilitation and Physical Therapy and Frontiers in Veterinary Science; Journal of Bodywork and Movement Therapies