By Dial A Vet Veterinary Team
Dogs and cats both vomit bile, the yellow or green fluid that comes up when the stomach is empty, but the likely reasons and the warning signs are not quite the same. Cats in particular are often assumed to be "just bringing up a hairball" when frequent vomiting is a sign of disease. And a cat that stops eating for even a few days can develop serious liver trouble. This page compares the two species so you know what to watch for. For a dog-focused guide, see dog vomiting yellow bile.
Key takeaways
- Bile in vomit means the stomach was empty. It points to timing, not to a specific disease.
- In dogs, common causes include an empty stomach, scavenging, gastroenteritis, pancreatitis, and swallowed objects.
- In cats, common causes include hairballs, food sensitivity, inflammatory bowel disease, hyperthyroidism, kidney disease, and string or thread swallowed during play.
- Vomiting more than once or twice a month is not "normal" for a cat and is worth a vet check.
- Repeated vomiting, lethargy, a painful belly, blood, or a pet who stops eating needs prompt veterinary care.
Why bile ends up in vomit
Bile is released into the small intestine to help digest fat. When the stomach is empty, a small amount can flow back into it. If the stomach is irritated, or the animal is nauseous for any reason, the vomit will be mostly bile and froth. That is why bile vomiting is common first thing in the morning, after a long fast, or after a pet has already vomited its food.
Common causes in dogs
- Long gaps between meals, sometimes as part of bilious vomiting syndrome
- Dietary indiscretion, bins, compost, and fatty scraps
- Pancreatitis
- Swallowed objects causing an obstruction
- Infections such as parvovirus, especially in unvaccinated puppies
- Toxins and medications
- Liver, kidney, or hormonal disease
Common causes in cats
- Hairballs. Occasional hairballs happen, especially in long-haired cats. Frequent hairballs can point to over-grooming or a gut motility problem.
- Eating too fast or a food sensitivity. Some cats vomit soon after gulping food.
- Inflammatory bowel disease and intestinal lymphoma. These often cause chronic vomiting, weight loss, and appetite changes in middle-aged and older cats. See frequent vomiting in cats.
- Hyperthyroidism. Common in older cats, often with weight loss despite a big appetite. See hyperthyroidism in cats.
- Kidney disease. Nausea is common as chronic kidney disease progresses.
- Linear foreign bodies. String, tinsel, ribbon, and hair ties can bunch up the intestines and are an emergency.
- Toxins. Lilies are extremely dangerous to cats, and many household chemicals cause vomiting.
Key differences owners should know
Cats hide illness well, so a cat who vomits and then hides or skips meals may be sicker than it looks. Cats that stop eating, particularly overweight cats, can develop hepatic lipidosis (fatty liver), a serious condition that can start after just a few days without food. Dogs are more likely to vomit after scavenging and more prone to large-breed emergencies such as bloat. In both species, puppies, kittens, and seniors dehydrate quickly.
When it is urgent
Go to an emergency veterinary hospital straight away if your dog or cat:
- Vomits repeatedly or cannot keep water down
- Vomits blood or "coffee ground" material
- Is lethargic, weak, hiding, or collapsing
- Has a painful or swollen belly, or a dog retches without producing anything
- May have swallowed string, a toy, bones, medication, lilies, or another toxin
- Has yellow gums or eyes
- Is a cat that has not eaten for more than a day, or a young kitten or puppy that is vomiting
If you see string hanging from your cat's mouth or bottom, do not pull it. Take your cat to a vet.
How vets diagnose and treat it
Your vet will take a detailed history (frequency, timing, relationship to meals, appetite, weight change, and stools) and examine your pet. Tests may include blood and urine tests, a thyroid test in older cats, a pancreas test, faecal tests, and X-rays or ultrasound. Cats with chronic vomiting sometimes need intestinal biopsies to tell inflammatory bowel disease from lymphoma. Treatment depends on the cause and can include fluids, anti-nausea medication, diet changes, treatment of the underlying condition, or surgery for a blockage.
Prevention and management
- Feed regular meals. For cats, puzzle feeders or slow-feed bowls can help fast eaters.
- Brush long-haired cats regularly to reduce hairballs.
- Keep string, hair ties, tinsel, and lilies out of reach of cats.
- Secure bins and fatty food from dogs.
- Change diets gradually and only on your vet's advice for pets with sensitive stomachs.
- Book regular senior checks so problems like thyroid and kidney disease are picked up early.
FAQ
Is it normal for cats to vomit regularly?
No. Many people think frequent vomiting is just "what cats do", but regular vomiting is often a sign of a treatable condition. Mention it to your vet.
My cat vomits bile in the morning. Could it be the same as in dogs?
Some cats do vomit on an empty stomach, and feeding changes can help. A vet should still check for other causes first, especially in older cats.
Can I give my pet a human anti-nausea medicine?
No. Many human medications are unsafe for pets, especially cats. Ask your vet.
Talk with a vet
If your dog or cat has been vomiting and you are unsure whether it needs a clinic visit, our vets can talk it through with you by video. Book a consult at dialavet.com. If your pet is vomiting repeatedly, seems weak, or may have swallowed something dangerous, go to an emergency vet hospital now.
References
- Merck Veterinary Manual. Vomiting in Small Animals.
- Cornell Feline Health Center. Vomiting in Cats; Hepatic Lipidosis.
- International Cat Care. Vomiting and hairballs in cats.
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. If your pet is vomiting repeatedly or seems unwell, contact a veterinary hospital promptly.