Why is my dog vomiting?

How vomiting actually happens

Picture one alarm bell in your dog's brain. Four separate wires can ring that bell, and silencing the bell never fixes the wire.

Once you can see four wires instead of one, the long list of possible causes stops being frightening and starts being a map. It also explains something that surprises most pet parents: a dog with a perfectly healthy stomach can still vomit.

Where the four wires sit

The same reflex, reached from four different places in the body. Tap a point to see which wire it belongs to and what it means for your dog.

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Start hereWire one: the gut

The stomach and intestine. Spoiled food, a sudden diet change, worms, infection, or a swallowed object all send signals from here. A blockage behaves like a blocked drain: whatever goes in has nowhere to go but back up.

1. Wire one: the gut. The stomach and intestine. Spoiled food, a sudden diet change, worms, infection, or a swallowed object all send signals from here. A blockage behaves like a blocked drain: whatever goes in has nowhere to go but back up.
2. Wire two: kidneys and liver. When these organs stop clearing waste properly, that waste builds up in the blood and reaches the patch of brain that samples it directly. The dog vomits because the blood is dirty, not because the stomach is damaged.
3. Wire three: the inner ear. The inner ear tracks balance. A car journey can disturb it, and that disturbance causes nausea and then vomiting, with a completely healthy digestive system.
4. Wire four: the brain. Severe pain, fear, a head injury, or rising pressure inside the skull can trigger the vomiting reflex directly, without any signal from the stomach.

Is it vomiting, or regurgitation?

This is the first thing a vet works out, because it splits the possibilities almost in half. Most pet parents have never been told there is a difference.

Watch which one your dog does, and if you can film it, film it. That clip is often worth more to a vet than a long description.

When the problem is the gut itself

Dietary indiscretion is far and away the commonest cause. It is the leftover curry from last night's function, the plate someone left on the floor, the child who slipped him something under the table, or whatever he found on the walk and swallowed before you could stop him.

• A sudden change of diet does the same thing even when the new food is better quality. Gut bacteria need days to adjust, not hours.
• Worms and intestinal parasites are common and frequently missed, especially in puppies and dogs with outdoor access.
• Infection. In an unvaccinated or partly vaccinated puppy, vomiting with diarrhoea, often bloody, must be taken seriously. Parvovirus moves fast and dehydrates a puppy in hours.
• Obstruction behaves like a blocked drain. A toy, a mango stone, a bone fragment or a length of thread lodges in the gut, and whatever goes in comes back up. The dog gets worse rather than better, and this is not one to watch overnight.

When the gut is fine and the problem is elsewhere

This is the part almost nobody expects, and it is why a vomiting dog sometimes needs a blood test rather than a stomach medicine.

When the kidneys stop clearing waste properly, that waste builds up in the blood and reaches the patch of brain that samples it directly. The dog vomits because the blood is dirty, not because the stomach is damaged. Liver disease works through the same wire. Pancreatitis often follows exactly the kind of rich, fatty meal described above, and brings a painful belly and a dog who will not eat.

Hormonal disease belongs here too. Adrenal insufficiency is known among vets as the great pretender: vomiting comes and goes for weeks, the dog seems to recover, then slips again.

Toxins, medicines and irritants

Some things ring the bell by scraping the stomach lining directly. Others are absorbed into the blood and reach the chemical sniffer. Either way, the dog vomits.

• From outside the body: chocolate, xylitol in sugar-free gum and sweets, grapes and raisins, onion and garlic in quantity, rat poison, insecticides, cleaning fluids, and certain houseplants.
• Human medicines are a serious and avoidable problem. Painkillers made for people are among the commonest causes of poisoning in pets worldwide, and they can strip and ulcerate a dog's stomach lining.
• Never give your dog anything from your own medicine box, repeat a medicine prescribed for a previous illness, or use leftover antibiotics.

When the trigger is balance, or the brain itself

These two are short, but leaving them out is what makes vomiting look random.

The inner ear tracks balance. A car journey disturbs it, that disturbance causes nausea, and the nausea causes vomiting. The digestive system is not involved at all, which is why a dog can vomit in the car and eat normally an hour later. If your dog does this on every journey, it is worth raising — it is manageable, not something to simply put up with.

The brain can also trigger the reflex on its own. Severe pain, real fear, a blow to the head, or rising pressure inside the skull can all set it off with no signal from the stomach. Vomiting after a fall, a road accident, or alongside unsteadiness, a head tilt, circling or a change in behaviour is not a digestive problem and should be seen the same day.

What came up tells you something

Look before you clear it away. The colour and content genuinely narrow things down.

• Yellow or greenish fluid usually means an empty stomach and bile that has flowed backwards into it. Early in the morning, in a dog who is otherwise well and holding weight, that often just means too long a gap between meals. A small late meal frequently settles it — though this is a conclusion a vet reaches by ruling other things out, not a label to give your own dog.
• White foam is saliva and stomach fluid from an empty or irritated stomach. Be careful here: repeated retching that brings up only a little foam, in a dog whose belly looks swollen, is an emergency rather than an upset stomach.
• Undigested food some hours after eating suggests the stomach is not emptying as it should.
• Blood, either fresh red streaks or dark grainy material that looks like wet coffee grounds. Most owners do not recognise coffee-ground vomit as blood at all. It is.
• A stool-like smell points towards a blockage low in the gut and needs urgent attention.

Watching safely at home: resting the gut

Rest the gut, but do not starve it. For vomiting that looks like it came from the gut itself, hold food for six to twelve hours. Where the trigger is clearly a car journey, three to six hours is enough before offering food again.

That window does two jobs. It gives an irritated stomach lining time to settle, and just as importantly it is a test: if your dog is still vomiting when there is nothing to bring up, this is not a simple upset and it is time to see a vet.

Water matters as much as food. A dog who gulps a full bowl after vomiting will very often bring it straight back up, so offer a small quantity every twenty to thirty minutes instead. When you restart food, give a fraction of a normal meal, plain and bland, and build back up over the following day.

• No curd. It can aggravate an already inflamed stomach.
• No homemade electrolyte drinks. Unknown sugar levels and flavourings are the last thing a nauseated dog needs. No rice water either.
• If you want to offer something other than water, plain coconut water in small amounts is the kinder option.
• Do not extend the fast on your own. Going without food for a long stretch does its own harm; the point is a short, deliberate rest.