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What are Some Causes of Blood in the Stool of Animals?

Sheri Cyprus
Sheri Cyprus

Bright red blood in the stools in animals is called hematochezia and it signifies lower intestinal tract bleeding. Black, tarry blood is called melena and it signifies upper intestinal tract bleeding. Blood in the stools is often caused by internal parasites, allergies, bleeding ulcers, ingested blood or gastrointestinal diseases.

Internal parasites cause blood in the stools in animals due to the irritation the parasites create in the digestive tract. Hookworms survive on the blood in the small intestine and often cause anemia which can often be noticed by pale gums as well as black blood in the stools. Puppies are especially susceptible to serious harm or death from hookworms.

Blood in puppies' stools can be caused by hookworms.
Blood in puppies' stools can be caused by hookworms.

Whipworm infestations affect the colon and can cause bright red stools. It is quite rare in cats, but fairly common in dogs. Whipworms look like long whips and the eggs can be seen in a fecal exam. By the time the blood appears, there is likely to be a large number of the parasites in the animal's colon.

Bright red blood in the stools may also be caused by food allergies. An allergic reaction may be likely if blood is accompanied by other allergy symptoms in animals such as constipation or diarrhea, ear infections, rashes or skin infections. Itchiness is another symptom of allergies in animals.

Inflammatory bowel disease if common in cats.
Inflammatory bowel disease if common in cats.

Bleeding ulcers in the stomach or the esophagus causes black blood in the stools in animals. Bleeding ulcers are also called peptic ulcers. An ulcer is an open sore caused by an irritant such as an acid, drug or bacterium. Ingested blood, such as from killing and eating prey, is another cause of black stools.

Gastrointestinal diseases also cause blood to appear in the stools. Black blood is often associated with lymphoma. Lymphoma is a cancerous condition of the white blood cells and is fairly common in dogs. Inflammatory Bowel Disease (IBD)is fairly common in cats. Blood in the stools in animals with IBD is sometimes the only symptom of the disease. The blood occurs as the cells in the digestive tract become inflamed.

Frequently Asked Questions

What are common causes of blood in an animal's stool?

Bleeding ulcers in the stomach may cause black blood in the stools of animals.
Bleeding ulcers in the stomach may cause black blood in the stools of animals.

Blood in an animal's stool can be caused by a variety of conditions, including parasitic infections like hookworms or giardia, inflammatory bowel disease, dietary indiscretion (eating something they shouldn't have), ulcers, or even cancer. It's important to consult a veterinarian if you notice blood in your pet's stool to determine the underlying cause.

Can dietary changes lead to blood in an animal's stool?

Bleeding ulcers are also called peptic ulcers.
Bleeding ulcers are also called peptic ulcers.

Yes, sudden dietary changes can disrupt an animal's digestive system, leading to irritation or inflammation of the colon, known as colitis, which can result in bloody stools. Always transition your pet's diet gradually and be mindful of their reactions to new foods to avoid gastrointestinal upset.

How can parasites cause bloody stools in animals?

Parasites such as hookworms, whipworms, and giardia can damage the intestinal lining, causing bleeding. According to the Companion Animal Parasite Council, hookworms are particularly concerning as they feed on the animal's blood, leading to potentially life-threatening anemia, especially in young puppies and kittens.

Is blood in an animal's stool always a sign of a serious condition?

Not always. While blood in the stool can indicate a serious health issue, it can also be caused by less severe problems like constipation or a small rectal injury. However, it's crucial to monitor the situation closely and seek veterinary advice, as it could also be a symptom of a more significant health concern.

What should I do if I notice blood in my pet's stool?

If you notice blood in your pet's stool, it's important to contact your veterinarian promptly. They may recommend diagnostic tests such as fecal examinations, blood tests, or imaging to determine the cause. Treatment will depend on the diagnosis and may range from deworming and antibiotics to dietary management or surgery.

Can stress cause blood in an animal's stool?

Stress can indeed lead to gastrointestinal upset in animals, which may manifest as blood in the stool. Stress colitis is a condition where stress disrupts the normal function of the colon, leading to inflammation and bloody diarrhea. Managing an animal's stress through environmental enrichment and routine can help prevent such occurrences.

Discussion Comments

rallenwriter

About once every few months my dog has a bleeding bowel movement, and I'm really desperate to know what could be going on.

I've had him tested for all kinds of worms, and nothing has come back positive, and they say he doesn't have cancer.

He's an inside dog, so he doesn't eat anything bloody, and I don't think he has an ulcer or anything.

What could be some other causes of intermittent bloody stools in dogs?

I'm really worried about him, and I've tried changing his diet a few times, so I'm really running out of options.

What should I do?

Planch

What would be some of the causes of bloody stools in an inside cat who only eats store-bought food? She has been an inside cat for as long as I've had her, but recently she's started having bleeding bowel movements.

I'm just afraid that it's one of the more serious bloody stool causes, since she's getting older, and has also been throwing up more often than usual.

What do you think?

TunaLine

My dog has never had blood in his stool before, but last night he got out (he's usually an inside dog), and was out all night in the woods around our house.

This morning he's had several dark, tarry stools, and I was really wondering what could be causing him to have so many stools with blood.

I was thinking that since it happened so suddenly, that he might have just had a crazy night and eaten a lot of animals or something last night, and the blood from the animals might be causing the weird stools.

He hasn't had any other symptoms besides blood in the stool, but I'm still a little worried about it. Should I take him to the vet, or give it a few more days?

mach1busta

I have a bulldog that has been bleeding through his rectum every time he goes to the bathroom. It's been almost a year now and the doctors have taken his blood and only come back with an enlarged prostate that may be causing this type of pressure. (The prostate is very large). However, when he comes back and I'm wiping him I do notice a little bean like deposit protruding from his anal area that is a blood like color. The blood when I wipe is a bright red color. He has not lost appetite and is very well otherwise. I just don't like to see the blood and it's been soo long I don't want it to be cancer.

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    • Blood in puppies' stools can be caused by hookworms.
      Blood in puppies' stools can be caused by hookworms.
    • Inflammatory bowel disease if common in cats.
      By: squidmediaro
      Inflammatory bowel disease if common in cats.
    • Bleeding ulcers in the stomach may cause black blood in the stools of animals.
      By: V&P Photo Studio
      Bleeding ulcers in the stomach may cause black blood in the stools of animals.
    • Bleeding ulcers are also called peptic ulcers.
      By: designua
      Bleeding ulcers are also called peptic ulcers.