What Causes My Dog to Have Bloody Stools?

Blood in a dog's stool is never normal and should be treated as soon as possible by your veterinarian. Blood from the stomach or upper small intestine will be black and tarry looking. Bright red blood in the stool is caused by bleeding in the lower gastrointestinal tract (colon or rectum). Treatment will depend on the cause. If treated early, the dog should recover with no problems.

  1. Medicine Ingestion

    • Ingestion of common over-the-counter medications such as aspirin, ibuprofen or naproxen can cause bloody stools. Call your veterinarian to see if you should give any antidote or treatment at home. Do not induce vomiting unless directed to by your veterinarian. Take the dog immediately to your veterinarian along with the bottle if available. Never give any aspirin, ibuprofen or other human medications to your dog unless ordered by your veterinarian, and be careful to not leave containers in an area where your dog can get to them.

    Hemorrhagic Gastroenteritis

    • This is a sudden onset of bloody diarrhea of which the exact cause is unknown. Clostridium perfringens and E. coli are possible causes, along with nutritional disorders. Younger puppies and small breeds are more susceptible.

    Parvo

    • Canine parvovirus or CPV type 2 is a contagious disease transmitted by contact and in the air or by the ingestion of feces that contains virus particles. Recovered dogs are still carriers for the virus. Parvo can survive for years in soil, so an area in which an infected dog lived must be thoroughly cleaned before other animals should be allowed in the area. This may involve removal of the top layer of grass or dirt.

    Parasites

    • Parasites can cause bloody stools. Hookworms, roundworms, heartworms and whipworms feed on the host's blood. Infection must usually be severe before the onset of bloody stools is seen. Hookworms are of special concern because they are contagious to humans. Never go barefoot in areas where dogs defecate and wash your hands after handling stool.

    Masses, Polyps and Tumors

    • Masses, polyps and tumors can cause bleeding and may be one of the first signs of cancer. Biopsies and blood work must be done before making a definitive diagnosis. Treatment usually involves surgery to remove the mass.

    Other Causes

    • Other common causes of bloody stools include inflammation of the rectum or colon and the passing of foreign bodies, such as bones and other sharp non-food items the dog may have consumed. Sudden changes in diet or feeding people food can cause bloody stools.

    Treatment

    • Treatment will depend on the cause. In case of inflammation or parasites, treatment may require antibiotics such as Flagyl or tetracycline and worming the dog. Severe blood loss and loss of fluids and electrolytes may need IV fluid replacement. Foreign body ingestion and masses can require surgery. Milder cases may respond to symptomatic treatment, such as changing the diet.

      With so many causes and treatments, never guess when your dog has bloody stools or try to self-treat. Take the dog to the veterinarian immediately so proper treatment can begin. The earlier treatment begins, the better it is on the dog and the better chance of full recovery.