It is 5am. You are woken by an unmistakable noise and by the time you get the light on your dog has brought up a small puddle of yellow froth and nothing else. Ten minutes later they are bouncing around asking for breakfast as though nothing happened.
This is commonly known as the 'hunger pukes', but its clinical name is bilious vomiting syndrome, and when the pattern is classic and your dog is otherwise completely well, it is one of the few causes of vomiting in dogs that can sometimes be sorted out with a simple change at home.
Here is what is actually going on, what helps, and the signs that may mean it is something else.
What is Bilious Vomiting Syndrome in dogs?
Bilious vomiting syndrome (BVS) is vomiting that happens on an empty stomach. You may also see it called reflux gastritis or duodenal gastric reflux.
The classic picture is this:
- Vomiting in the early hours of the morning, or late at night before the next meal
- Yellow or greenish frothy fluid with no food in it
- A dog who is otherwise completely well, with a good appetite, normal energy, normal poos and no weight loss
- Sometimes a bit of nausea beforehand, such as lip smacking, drooling or eating grass
Bile is the greenish yellow fluid the liver makes to help digest fat. It is stored in the gallbladder and released into the small intestine after a meal. In bilious vomiting syndrome, bile and other fluid from the small intestine are thought to travel the wrong way, back up into the stomach, where they irritate the stomach lining and trigger vomiting. Changes in gastrointestinal motility during a long fast seem to play a part too.
How is Bilious Vomiting Syndrome treated?
Because the problem is an empty stomach, the treatment is to reduce the amount of time the stomach remains completely empty. In most dogs, adding a small meal right before bed may be enough to stop the vomiting. Some dogs also benefit from being fed promptly in the morning.
Importantly, that bedtime snack should usually come from your dog's normal daily food allowance, rather than being an additional meal on top of it. Otherwise, those extra calories can quickly lead to weight gain.
What is the best food for a dog with Bilious Vomiting Syndrome?
No particular diet has been established as a specific treatment for bilious vomiting syndrome, so I wouldn't recommend changing the dog's food if they are otherwise healthy and doing well on their current food. Also, changing only one thing at a time makes it much easier to work out what has actually helped.
However, diet may need to be investigated if the vomiting continues despite changing the meal timing, or if the dog has other gastrointestinal symptoms.
When is it not just the hunger pukes?
It is important to make sure that something more significant isn't causing the vomiting.
Vomiting is a symptom rather than a diagnosis and there are many possible causes, including dietary indiscretion, parasites, gastrointestinal inflammation, pancreatitis, foreign bodies, liver or kidney disease, endocrine disease and some cancers.
Book a vet visit if:
- The vomit contains food, especially food eaten hours earlier, or blood
- Vomiting happens more than once or twice a week, or is getting worse
- Your dog is losing weight, off their food, flat, or drinking more than usual
- There is diarrhoea, blood in the stools, black tarry stools or no stools at all
- Your dog is a puppy, or might have swallowed a 'foreign body' such as a sock, a toy, a bone or a stone
- It has started suddenly in an older dog
Ring your vet or an after hours clinic straight away if your dog is retching repeatedly without bringing anything up, has a swollen or painful belly, or is restless and distressed. That combination can mean bloat, which is a true emergency.
Frequently asked questions
Is Bilious Vomiting Syndrome dangerous?
In an otherwise healthy dog with a typical pattern, BVS itself is not generally considered dangerous. The risk is assuming recurrent vomiting is BVS when something else is causing it, which is why it is worth a vet check if you see any of the other symptoms listed above.
What should the bedtime meal be?
Ideally a small portion of the food they already eat, taken out of their daily allowance. There is nothing magic about the type. What matters is that there is something in the stomach.
Can I give a treat before bed instead of a meal?
You can, and for some dogs it is enough. Small treats digest quickly though, so a portion of complete food will usually buffer for longer. If you do use treats, keep all treats to under 10% of daily calories so the rest of the diet stays balanced.
Do puppies get the hunger pukes?
Puppies do vomit bile on an empty stomach, but puppies also have far more serious reasons to vomit, including parasites, parvovirus, obstruction from something swallowed, and low blood sugar in small breeds. Do not treat a vomiting puppy at home. Ring your vet.
Will switching dog food fix it?
Usually not on its own, and if you change the food and the feeding schedule at the same time you will not know which one helped. Change the schedule first, keep everything else constant. If the vomiting continues despite the change talk to your vet.
The short version
If your dog vomits yellow bile on an empty stomach and is well in every other respect, shorten their fast. A small late meal, taken out of the daily ration, sorts it for most dogs. If it does not, or if anything on the red flag list above applies, that is a conversation for your vet.
