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Is Bloody Diarrhea in Dogs an Emergency?

Dr. Mark is a veterinarian. He has been working with dogs for more than 40 years.

The best thing you can do to increase your dog's chances of surviving a bout of bloody diarrhea is to take him to the vet immediately.

The best thing you can do to increase your dog's chances of surviving a bout of bloody diarrhea is to take him to the vet immediately.

What Should You Do If Your Dog Has Bloody Diarrhea?

It is the middle of the night. Your dog wakes you up whining, and when you take him outside you notice that he has bloody diarrhea. Do you take him to an emergency veterinarian or wait to see your regular veterinarian in the morning?

There are several things to look at in order to make that decision.

What Condition Is He In?

Is your dog still behaving normally or does he appear to be in distress? If he is displaying unusual behaviors or appears to be in pain, the situation may be urgent.

Are There Other Symptoms?

The presence of other symptoms in addition to bloody diarrhea may also indicate an emergency situation. Such symptoms might include:

  • vomiting
  • depression
  • blood in the urine
  • difficulty breathing

What Kind of Blood Is It?

This is one of the easiest indicators as to whether an emergency vet visit is necessary.

If it is fresh blood (hematochezia) it should be considered more of an emergency as dogs can dehydrate and die. Melena can be less serious, but if your dog has been outside or had access to any poisons, it is an emergency.

Bright Red Blood (Hematochezia)

Bright red blood in the stool indicates that it has not had time to digest and is from the colon or rectum. This is called hematochezia. Dogs with bright red blood can be suffering from:

  • acute hemorrhagic diarrhea syndrome (AHDS, known as hemorrhagic gastroenteritis)
  • colitis
  • poisoning
  • trauma
  • hookworms and other parasites
  • inflammatory bowel disease (IBD)

Black, Tarry Blood (Melena)

Black, tarry stools mean that the blood has already been digested. This is called melena. Dogs with digested blood in their stool may have:

  • parasites
  • trauma to the mouth, esophagus, or stomach
  • ulcer
  • tumor
  • poisoning
  • infection
  • liver disease
  • other less common possibilities (pancreatitis, aspirin, etc.)

Could It Be Constipation?

A constipated dog can have dry stools and a spot of blood on the top of the stool and that can be taken care of the next day.

When Bloody Diarrhea Is an Emergency

Bloody diarrhea almost always justifies a visit to an emergency clinic, but it should always be considered an emergency if:

  • your dog is a puppy
  • your dog has not completed all of his vaccinations
  • your dog is very tiny (Maltese, Yorkie, Chihuahua, etc.)
  • your dog is also vomiting or has other symptoms
  • your dog has had acute hemorrhagic diarrhea syndrome (hemorrhagic gastroenteritis) or other bloody diarrhea in the past

Most dogs are okay after treatment, and 96% of dogs go home even after a serious disease like AHDS. (1) Without a visit to an emergency clinic, however, more of them are going to die.

How to Help a Dog With Bloody Diarrhea Without Going to the Vet

If you choose not to take your dog to a veterinarian or there is no veterinarian available in your area, you can try fasting your dog. The fast needs to last about a day, and after that their diet should be bland so as to not upset the bowel. (Boiled hamburger and rice are often used.)

Dogs on a fast still need access to water. They also need to be treated for dehydration, since diarrhea pulls fluid out of the stool that would normally be absorbed. Intravenous fluids at a clinic are best, but at home, you can treat dehydration by giving coconut water or Pedialyte.

The Best Thing to Do Is Take Your Dog to the Vet

This is not going to help if your dog has a condition that causes dehydration and changes in the blood. The best thing you can do to increase your dog's chances of surviving a bout of bloody diarrhea is to take him to the veterinarian immediately.


(1) Dupont N, Jessen LR, Moberg F, Zyskind N, Lorentzen C, Bjørnvad CR. A retrospective study of 237 dogs hospitalized with suspected acute hemorrhagic diarrhea syndrome: Disease severity, treatment, and outcome. J Vet Intern Med. 2021 Mar;35(2):867-877.

This article is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from your veterinarian. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2022 Mark dos Anjos DVM