Bloody Stool

Q. Could changing a dogs food cause a very small amount of blood to appear in the stool and diarrhea?

A. Blood in a dog's stool and diarrhea is always a concern, and your question about how a diet change might cause this is a good one.

The most probable cause of bloody stool and diarrhea is parasites, such as roundworms and hookworms--especially in puppies. All puppies should be dewormed every two three weeks starting at 4 weeks of age, up until they are old enough to go on a monthly dewormer.

In any dog, a diet change can cause the populations of bacteria that normally live in the intestine to change, resulting in a GI system that is out of balance. Sometimes, bacteria called Clostridium can overgrow in the intestine and secrete a toxin that causes the lining of the large intestine to bleed. Fortunately, an overgrowth of Clostridium can be seen on a microscopic exam of a stool sample. Treatment is usually successful with the appropriate antibiotics.

Ideally, you will minimize how often you change your dog's diet. Although it may seem boring to you and I, most dogs are quite happy eating the same thing every day. After a diet change, wait several days to see if your dog's stool appears to be normalizing. If your dog still has diarrhea, small amounts of plain yogurt can help repopulate the gut with healthy bacteria.

Best,
Jon Geller, DVM

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