Why is my dog being sick and what does the colour of my dog’s vomit mean?

Why is my dog being sick?

Vomiting in dogs is their body’s way of getting rid of something it doesn’t like. You might see signs like drooling, gagging, or heaving before it happens. It’s different to regurgitation, which is a passive process and often just undigested food coming up soon after eating.

Dogs are, unfortunately, quite good at vomiting. Their bodies are hard-wired to do it as a defence mechanism. Here are some of the most common causes:

• Dogs often vomit after eating something they shouldn’t, like wrappers, bones or leftovers
• A sudden diet change or rich food can upset their stomach and cause sickness
• Vomiting may be triggered by parasites or infections that affect the gut
• Potentially fatal toxins, such as chocolate, grapes, mouldy food, or household cleaners, can lead to vomiting as an early warning sign
• Motion sickness, especially in puppies, can cause vomiting during car journeys
• Stressful situations like loud noises or changes in routine can sometimes lead to tummy trouble
• Vomiting may signal more serious issues like pancreatitis or organ problems such as kidney disease
• Blockages or bloat can cause vomiting or unproductive retching, both need urgent veterinary attention

If you see your dog vomit, take a note (or photo) of what it looked like, what they did beforehand (e.g. ate grass, got into the bin, went on a car ride), their current diet (including any recent changes), and how they’re behaving now. These details can help your vet figure out what’s going on. Remember, vomiting can quickly lead to dehydration, so don’t wait too long to get help if you’re unsure.

Dog vomit colour chart

One thing you can do when your dog vomits is to look at the colour as this can offer clues about the cause. Vomit comes in many colours – yellow, green, white, brown, red, black, even clear. Each hue can hint at different things. To help you decode the mess, here’s a handy chart summarising common vomit colours and what they might mean. Just be aware that these are general guidelines and not a sure diagnosis.

Yellow (or yellow-orange)
What it might mean: Often contains bile, which may be present when the stomach is empty or irritated. Can also appear after eating something yellow. Repeated yellow vomiting may be linked to liver, gallbladder or digestive issues.
What to do: If it's a one-off and your dog seems well, offer a small bland snack and monitor. If it happens regularly or your dog seems unwell, speak to your vet.

White & foamy
What it might mean: Could be gastric foam from an empty stomach, or saliva. Also seen with acid reflux, mild stomach irritation, or after retching. In bloat (GDV), dogs may bring up white foam repeatedly.
What to do: Monitor if it's a single episode and your dog is otherwise bright. If retching continues or your dog’s abdomen is distended or painful, seek emergency vet care.

Green
What it might mean: May contain grass or bile. Dogs often eat grass, which can cause green-tinted vomit. In rare cases, green vomit could indicate poisoning (e.g. rodenticide or slug bait).
What to do: If your dog just ate grass and seems otherwise normal, monitor. If they didn’t eat grass, the vomiting continues, or you suspect poison exposure (especially if the vomit is very bright green), call your vet.

Brown
What it might mean: Could be digested food, faecal material, or digested blood. Foul-smelling or dark brown vomit may point to a blockage or bleeding in the digestive tract.
What to do: If it smells like food and your dog seems well, monitor. If there's a foul odour, signs of illness, or a coffee-ground appearance, seek vet advice urgently.

Red or pink
What it might mean: Indicates the presence of fresh blood. May come from the mouth, oesophagus, or stomach. Bleeding could be from irritation, ulcers, or internal injury.
What to do: Always call your vet if you see blood in vomit. Even small streaks should be checked, especially if there are other symptoms or repeated vomiting.

Black (or very dark)
What it might mean: Often suggests digested blood, commonly from stomach or intestinal bleeding (e.g. ulcers or tumours). Sometimes confused with mud or soil.
What to do: Seek urgent vet help. Try to collect a sample or photo to help with diagnosis.

Clear (transparent liquid)
What it might mean: Usually water or saliva. Can happen after drinking too quickly, or during regurgitation or acid reflux.
What to do: Monitor for repeated vomiting or signs of nausea. If your dog keeps vomiting clear fluid, especially in the morning or with other symptoms, speak to your vet.

Blue, teal or unusual colours
What it might mean: May be linked to ingestion of toxins like slug pellets or rat poison, which are often dyed for identification.
What to do: Treat this as a medical emergency. Get to a vet immediately, and if possible, bring any packaging or product with you.

Read more: Protecting your dog from common poisons

Dog vomiting do’s and don’ts

If your dog has just been sick, there are some steps you can take to help them feel better. Here are some do’s and don’ts for caring for a vomiting dog at home:

• Do keep them hydrated by ensuring fresh water is available. Just remember to wait a few minutes after vomiting before allowing small sips of water. Avoid letting them gulp large amounts, as that might trigger more vomiting.
• Do let your dog rest, keep them warm and comfortable in a quiet area and allow them to sleep if they want.
• Do feed a bland diet, such as boiled white chicken or white fish with plain rice. Offer a tablespoonful at a time to start with (two if they’re a large breed), every hour or so.
• Do stick to bland food for 24–48 hours, feeding little and often. If there’s no more vomiting, you can then gradually mix in their usual food over a day or two.
• Do observe and comfort your dog and take note of how many times they vomit and anything unusual in it (like blood or objects). Jotting these notes can help if you end up at the vet.
• Don’t give any human medications, such as anti-nausea or anti-diarrhoea meds like Pepto-Bismol or Imodium, as these can be dangerous for dogs.
• Don’t feed rich treats or table scraps, especially fatty foods like burgers, bacon, etc as these can worsen the irritation.
• Don’t force-feed your dog food or water, as this can lead to more vomiting. If every time they drink or eat, they vomit, seek urgent veterinary advice.

When to call the vet

Most of the time, a one-off vomit isn’t anything to worry about, and many mild stomach upsets will resolve within 24 hours. But if your dog keeps being sick or shows other symptoms, it could be a sign that something more serious is happening. Here’s when to call your vet:

• You see blood in their vomit, such as fresh red streaks or vomit that looks like dark coffee grounds (digested blood).
• You know (or suspect) they’ve eaten something dangerous, such as chocolate, slug pellets or rat poison.
• Vomiting is nonstop or very forceful, including repeated or projectile vomiting, as this could point to a blockage or toxin.
• They’re retching without bringing anything up, as this can be a sign of bloat, especially if their tummy is swollen or hard. Bloat is a life-threatening emergency.
• They have other worrying symptoms, such as diarrhoea, shaking, a hunched posture, fever, pale gums, or collapse. 
• They can’t keep water down, so if your dog throws up every time they drink, it’s a sign they may not be able to stay hydrated.
• They’re sick more than two or three times in a day, or the vomiting continues for more than 24 hours.
• They’re very young or very old, puppies and elderly dogs are at higher risk.
• They’re not improving with home care, even though you’ve tried resting their tummy and feeding a bland diet.
• They’re unwell in themself, such as being very lethargic, not wanting their usual interactions with you or hiding away.

You know your dog best. When in doubt, err on the side of caution and get professional help. Vets will happily advise if something can be managed at home. 
 

Dog vomiting treatment

If your dog needs to see the vet, they’ll likely:

• Ask about the vomit (timing, colour, what they might have eaten)
• Check them over for hydration levels, stomach pain, temperature, and more
• Run tests such as bloodwork, urine, scans, or x-rays if needed
• Treat with fluids or anti-nausea medicine
• Advise on diet and rest at home, or in some cases, admit for monitoring or surgery

Why is my puppy being sick?

If your puppy is vomiting, has diarrhoea, or is struggling to eat or drink, it’s best to contact your vet. While it may be something mild, puppies are more vulnerable than adult dogs, and conditions like parvovirus, dehydration or blockages can become serious quickly.

They’re still building their immune system, so are more prone to infections, and are more vulnerable to fluid loss, so even a simple upset can lead to dehydration. Offer small sips of water regularly and keep a close eye on their behaviour. Puppies also need regular food to maintain their energy, and just a few hours without it can lead to low blood sugar.

Worms are another common cause of sickness in puppies. Heavy infestations may even be visible in vomit or poo, so it’s important to keep them up to date with deworming. Puppies also tend to chew and swallow things they shouldn’t, like socks, stones or bits of toys. If your puppy keeps being sick or isn’t passing poo, it could be a blockage.

Academic research into dog vomiting

What the data tells us about vomiting in dogs

A major UK study looked at the health of over 148,000 dogs seen at vet practices across the UK. It found that vomiting was one of the main reasons for dogs to visit the vet. This confirmed just how common it is in everyday practice.
Importantly, the study also showed that purebred dogs were more likely to be affected by several common conditions than crossbreeds, including issues linked to vomiting such as skin disease, obesity, and inflammation. These can all play a part in digestive upset.

What we know about vomiting in dogs — and what we don’t

This detailed review makes clear that the science behind vomiting in dogs is complex and can be triggered by many things. This includes tummy troubles, toxins, infections, organ disease, even motion sickness or brain signals. The vomiting reflex itself is controlled in the brain, which is why it can be hard to pinpoint a single cause.
This review confirms that while mild, short-term vomiting can be harmless, persistent or severe cases can be serious, leading to dehydration, shock, or even aspiration pneumonia. It also shows that many commonly used treatments, like anti-sickness medication, are helpful, but not always backed by strong clinical trials.
In many cases, supportive care like rest, hydration and bland food is enough. But the review stresses the need for early assessment, so vets can tell which cases are simple upsets and which need a deeper look.

Grass eating and vomiting – myth busted

It’s a question vets hear all the time: “Is my dog eating grass because they’re sick?” A major study set out to find the answer and what it found may surprise you.
Researchers surveyed thousands of owners and discovered that eating plants, especially grass, is normal dog behaviour. Around 80% of healthy dogs eat plants occasionally, and most do so without being ill beforehand or vomiting afterwards. In fact:

• Only 9% of dogs appeared unwell before eating grass
• Just 22% vomited afterwards
• Younger dogs were more likely to eat plants, especially non-grass ones

There was no link between plant-eating habits and a dog’s sex, neuter status, breed, or diet. And there was no evidence that dogs eat plants because they’re unwell or lacking nutrients.

Frequently asked questions

Why does my dog vomit early in the morning?

If your dog often brings up yellow foam or bile first thing, it could be due to an empty stomach. When dogs go too long without food, stomach acid and bile can build up and irritate the lining, a condition sometimes called bilious vomiting syndrome. A small snack before bed or feeding smaller meals more often can help. If it keeps happening, or your dog seems off their food or unwell, speak to your vet.

Can I give my dog anything at home to stop vomiting?

Never give human medicine as it can do more harm than good. The safest thing you can do at home is rest their stomach. That means offering small amounts of bland food regularly. Keep them hydrated with small sips of water. If vomiting continues, or if your dog seems unwell or won’t eat, don’t wait — speak to your vet. Proper anti-vomiting treatments, like injections, are only available through them.

Need more info?

Seeing your dog being sick can be worrying but you don’t have to guess alone. Trust your instincts. If they’re not themselves, reach out to your vet. And if you’re not already a member, this is where the Pet Health Club can really help. Our plans include regular check-ups, parasite treatments, and expert advice to catch issues early, before they become emergencies.