Bloody diarrhea in dogs could be the sign of a serious problem, such as hemorrhagic gastroenteritis, parasites, parvovirus or internal bleeding, notes The Bark, Pet Education.com and Canine Journal. Get the dog to the vet as soon as possible.
Dogs are at a high risk for dehydration if diarrhea is left untreated. Bloody diarrhea often looks black and tar-like.
Hemorrhagic gastroenteritis (HGE) is a condition that may be accompanied by vomiting. The stool becomes very watery and bloody, usually very quickly. Caused by a bacteria called clostridium, HGE is more common in smaller dogs. Dogs with this condition must be treated with fluid replacement and the vet will withhold food for at least 24 hours. Antibiotics are sometimes used as a treatment.
The canine parvovirus is a deadly disease that affects puppies and dogs that have not been vaccinated against the disease. Symptoms of the disease include severe vomiting, bloody, watery diarrhea and fever. This disease progresses very rapidly and the dog becomes dehydrated quickly. Death in small dogs and puppies may occur within 2 days of the onset of the disease.
Fresh blood may be a sign that the dog has a perforation of the large intestine, stomach or anal glands. Tar-like stools may indicate old blood in the system and could be associated with cancer or a tumor.