Unwell dogs produce strange and often unpleasant things! We’re sure we don’t need to go into too much detail there. We’ve written plenty of articles about vomiting, diarrhoea, blood and more before. What about vomiting up white foam? What does this mean? Read on to find out.

Why is it Foamy?

Standard vomit, as you no doubt know, is often chunky with bits of food in, especially if your dog has just eaten! The colour can vary. If their stomach is empty, it tends to be a bit more watery and yellow, due to the stomach bile. White foam is less common, but often means there is excess gas in the stomach. Gas mixes with stomach juices and swallowed saliva to create the bubbly liquid. If the stomach lining is inflamed, this can also add to the frothiness. 

An empty stomach, gassiness and stomach inflammation are not very specific. Thus many different intestinal diseases can cause your dog to vomit white foam. We will go into these in a moment. 

There is, however, another location where white foam may originate – in a similar way to the stomach, if excess liquid (oedema) in the lungs mixes with air, it creates a frothy foam. This may be coughed up or swallowed. Again, many respiratory tract diseases can cause inflammation, oedema and thus foam – a dog coughing harshly can often appear like they are vomiting.

Gastrointestinal Causes

Gastrointestinal diseases causing white foamy vomit range from simple gastroenteritis (an upset tummy!) to more serious infections like worms, Salmonella and Campylobacter, to problems with the liver, kidneys or pancreas, chronic GI inflammation, and even cancer. We’ve talked about all of these many times, so we won’t go into too much detail. It is rare for these diseases to just have foamy vomiting – diarrhoea, inappetence, weight loss, and changes in drinking are also quite common. 

Vets generally investigate foamy vomiting by starting with taking history and performing a clinical exam. Sometimes, this is enough for us to make a presumptive diagnosis and administer treatment, especially if your dog isn’t too unwell. Further investigation may include taking blood, urine, and faecal samples, performing ultrasound or x-ray imaging, endoscopy of the GI tract or taking biopsies. 

Respiratory Causes

As we said above, vomiting can sometimes be confused with retching or even coughing – thus, a dog with respiratory disease can sometimes be seen to be ‘vomiting’ up white foam. There are just as many respiratory diseases that can cause white foamy coughing as GI diseases. 

Canine infectious respiratory disease (CIRD) 

This is a very common group of infections causing a harsh hacking cough, commonly associated with white foam. You’ve definitely heard of its more common name, kennel cough (we are trying to move away from ‘kennel cough’, as it implies it can only be caught from kennels). CIRD is easily transmitted by close contact between dogs, especially young dogs. It is often self-limiting, or responds well to anti-inflammatories. Vaccination protects against many of the infectious agents causing CIRD.

Lungworms and Heartworms

These are parasites that reside in the respiratory tract and often cause coughing, difficulties breathing, exercise intolerance and even heart disease. Some are transmitted when dogs eat snails or other intermediate hosts, while others are directly transmitted by consuming the worm’s larvae. Diagnosis can be difficult, involving sampling the faeces or blood, imaging the respiratory tract, and taking samples from the lungs. We can treat them with anti-parasitic drugs. The most serious, Dirofilaria immitis, is transmitted via a mosquito bite – it is currently rare in the UK but is becoming more common in certain areas. Regular parasite control is important to protect against all lung- and heartworms, particularly for dogs travelling abroad.

Chronic diseases can cause chronic coughing with white foam as well 

These include canine chronic bronchitis (similar to asthma), idiopathic pulmonary fibrosis (Westie lung), eosinophilic bronchopneumopathy (an autoimmune disease) and even some cancers. If your dog has a long-term cough you should investigate – investigation may involve blood tests, x-rays of the lungs, bronchoscopy and sampling the lungs. Many can be controlled with long-term anti-inflammatories or immunosuppressives.


Some causes of foamy vomiting/coughing are emergencies and should be seen by a vet immediately! It is important to know these problems and what they look like so you can get your dog the best treatment as quickly as possible.

Gastric dilatation volvulus (GDV)

This is the fancy way of saying stomach bloat combined with stomach twisting. The exact causes are unknown, but is associated with rapid feeding, giant and deep-chested breeds like boxers and Dobermans, and exercise before or after feeding. The stomach fills with air (dilatation) and causes the stomach to float and twist (volvulus). This blocks the emptying of the stomach, causing swelling and retching or vomiting. It is often non-productive, but can produce white foam. If untreated, a GDV can result in the blood supply to the stomach and spleen being blocked, blood loss, septic shock and death. Blockages due to swallowing large objects can cause similar signs to a GDV. If your dog is trying to vomit but not producing a lot, and has a big bloated stomach, visit your vet immediately. 


This well-known and very nasty disease is most commonly seen in young puppies. It classically causes severe bloody diarrhoea, but can cause bubbly vomiting as well. Young dogs with parvovirus rapidly become dehydrated and anaemic, and can collapse. Treatment is difficult, and even with veterinary hospitalisation, not always successful. Luckily, vaccination can prevent infection. If your puppy has blood in their diarrhoea, please speak to your vet, particularly if they appear unwell. 

In imported or travelling dogs, watch out for rarer and even more serious conditions

There is one disease that, thankfully, most UK dogs will never encounter, but is the classic condition for a foamy mouth – rabies. The rabies virus is most commonly spread via infected bites. The furious form causes aggression, while the nervous form causes collapse and seizures. Both stages cause hypersalivation. It can be transmitted to humans – if not treated, it is almost 100% fatal. Luckily, the UK and much of Western Europe is rabies free, so the chances of your dog becoming infected is low. But for any frequent fliers, always ensure they are fully vaccinated against rabies and take care around wildlife – if you or your dog are bitten by a wild animal, please seek veterinary and medical assistance ASAP to prevent this deadly disease.

Finally, any of the other above diseases can be emergencies depending on different factors

If your dog is very lethargic, cannot walk, has collapsed, has severe vomiting or diarrhoea, has pale gums, is breathing very rapidly, is fitting, or has swallowed something toxic or that could get stuck, then please speak to your vet immediately. Often the quicker we see your pet, the more can be done to get them back on their feet.

Final Thoughts

In summary, your dog vomiting white foam could be a sign of either gastrointestinal or respiratory disease. Many of these diseases are common and easily treated, but some can be more chronic or even emergencies. If you have any concerns your dog is unwell, please seek veterinary advice immediately, particularly for the emergency situations listed above.

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