What to Do If Your Pet Starts Vomiting Blood 

When your pet starts vomiting blood, immediate care by a veterinarian can reveal what is causing the hematemesis.

 By: smekosh
Blood is not a good sign. By: smekosh

Vomiting blood is a potentially worrying sign — everyone should take notice if their pet vomits blood. However, if you see blood, do not panic; a few simple observations can greatly help your veterinarian decide on a course of treatment.

The first thing is to stay calm and check that it is blood in the vomitus rather than red-colored food. This may sound obvious, but many, many times I’ve had distraught clients bring in what they thought was bloody vomitus only to find the dog had stolen food containing red food dye.

However, those pet parents did exactly the right thing to seek professional advice. I’d far rather see a false alarm than miss a truly sick animal.

Check for the presence of blood by using a piece of moist white tissue. Touch it to the vomitus and look at the color of the paper. Blood creates an orange stain on the white tissue. It is also helpful to take a photograph and scoop up some of the sick to show the vet to gauge the amount of blood loss.


It is rare that hematemesis (vomiting blood) happens without other symptoms. Most conditions severe enough to cause bleeding in the stomach are accompanied by other signs such as weight loss and poor appetite, or if the problem comes on suddenly, diarrhea and weakness.


If a pet is taking any NSAID medications such as metacam or onsior — commonly prescribed painkillers — stop the medication immediately and seek veterinary advice. NSAIDs can interfere with the blood supply to the stomach lining and in extreme circumstances cause gastric ulcers. If the ulcer perforates, this can be very serious; prompt treatment is essential.

Another cause is hemmorhagic gastroenteritis (HGE), meaning sickness and diarrhea with blood. There are several bacterial and viral sources of infection that cause HGE; some, such as parvovirus, are life-threatening.

Rarely, animals get stomach cancer, and if a mass in the stomach ulcerates and bleeds, this causes bloodstained vomit. Other disorders that interfere with the blood’s ability to clot rarely present as vomiting. It is more likely the animal will bruise or bleed heavily from a minor skin wound.


Your veterinarian will want to run blood tests to check for new versus longstanding blood loss and check for signs of infection or organ failure. If no infectious cause is suspected, then imaging the stomach using ultrasound or an MRI scan can help show masses in the stomach wall, and an MRI will identify ulcers.

A biopsy may be necessary to put an exact name to the condition. This is sometimes done via an endoscope, or a laparotomy may be needed if full-thickness samples are required.


This depends on the cause. In the case of a gastric ulcer caused by NSAIDs, the painkiller should be stopped immediately and a medicine containing sucralfate, which binds to exposed mucosa to form a protective barrier while the stomach wall heals should be administered.

Your veterinarian may also prescribe antacid tablets to decrease the amount of stomach acid produced so the wall can heal. HGE cases need intensive supportive care to stop them getting dehydrated. This involves intravenous fluids, pain relief, anti-nausea drugs and antibiotics.

Stomach cancer needs to be surgically removed where possible.


Always give NSAIDs with or after food, since taking these drugs on an empty stomach predisposes to ulceration. Also, regular vaccination against preventable diseases such as parvovirus is essential for your dog’s well-being.


  • Clinical Medicine in the Dog and Cat. Michael Schaer. Publisher: Manson Publishing.


This pet health content was written by a veterinarian.

Dr. Pippa Elliott, BVMS, MRCVS

View posts by Dr. Pippa Elliott, BVMS, MRCVS
Dr. Pippa Elliott, BVMS, MRCVS, is a veterinarian with nearly 30 years of experience in companion animal practice. Dr. Elliott earned her Bachelor of Veterinary Medicine and Surgery from the University of Glasgow. She was also designated a Member of the Royal College of Veterinary Surgeons. Married with 2 grown-up kids, Dr. Elliott has a naughty puggle called Poggle, 3 cats and a bearded dragon.

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