Few things are more frightening than seeing blood in the stool, as this is sometimes a warning sign of cancer, at least in people. But in dogs and cats, it generally isn't quite that serious, says Michael Brothers, D.V.M., a veterinarian in private practice in Middletown, Conn. Still, blood in the stool is not normal; it always means that something is wrong.
When the blood is bright red and on the surface of the stool, there is a good chance that something sharp, like a bit of bone, scraped the lining of the large intestine and made it bleed. The bleeding may continue for a day or two, but it probably won't last much longer. Even small scrapes can cause a lot of bleeding, so don't be surprised when the stools appear quite red.
Blood in the stool may also be a sign of parasites, like whipworms, which are irritating the intestine wall. "They are like mosquitoes that make many tiny bites until your pet bleeds," says Dr. Brothers.
When the blood looks dark, dry, or tarry and is mixed with the stool, there may be a problem in the small intestine. Some viral infections can temporarily irritate the walls of the small intestine and make it bleed. Blood in the stool can also be a sign of colitis, an inflammation of the large intestine.
Finally, bleeding may be caused by an infection of the anal sacs -- two sacs on either side of the anus that contain a strong liquid that pets use to mark their territory. These sacs normally empty whenever your pet has a bowel movement. When the sacs are infected, however, they don't empty the way they should, causing them to swell. Having a bowel movement can irritate the area, causing blood to flow.
See Your Vet If...
- The surface of your pet's stool has spots or smears of blood
- His stool is dark and tarry-looking
- Pushing on your pet's belly causes her pain
- Your dog or cat hasn't eaten for 24 hours or more
- Her abdomen appears bloated
- She has eaten rodent poison, antifreeze, houseplants, or other harmful substances
- Your pet has been vomiting for more than a day or is vomiting blood
- There are worms or other parasites in the stool
- She has had diarrhea for 24 hours or more
- There is blood in the stool or it looks dark and tarry
- She is scooting across the floor, or the anal area looks swollen
- Your pet has gained or lost substantial amounts of weight
- She is having side effects from medication, like appetite loss or vomiting
- There are growths in the anal area
- There is a bulge in her throat
- She is drooling much more than usual
- Your pet vomits shortly after eating
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