Bloody mucus in your dog's stool can have many causes, including a variety of illnesses and parasites. Though bloody stool isn't always an indicator of poor health, you should still contact your veterinarian to rule out illnesses if it persists in your dog for more than a day or two.
Parasites
There are five main types of worms that your dog can acquire:
Any of these may cause bloody mucus in the stool, but the two most likely to cause it are hookworm and whipworm.
While many types of worms are apparent in your dog's stool or vomit, hookworms cannot be seen without a microscope and may instead cause bloody stool, anemia, weight loss, lethargy and diarrhea. True to their name, hookworms hook to your dog's intestine to suck blood from the tissue. This can cause bleeding in the intestines, which can often be found in the stool.
Whipworms are also not visible to human eyes and cause similar symptoms as hookworms, particularly bloody mucus in stool, anemia, weight loss and lethargy. Whipworms also attach themselves to your dog's intestines, causing intestinal bleeding, and are the most difficult parasite to eliminate.
Inflammatory Bowel Disease
Inflammatory Bowel Disease (IBS) is a general term used to refer to gastrointestinal infections that cause irritation and inflammation in the stomach and large and small intestines. This can often cause bloody mucus in the stool as well as:
- stomach pain
- diarrhea
- constipation
- nausea
- bloating
- gas
- loss of appetite
IBS can have many causes including poor diet and genetics. It is difficult to diagnose because it can usually only be diagnosed by ruling out other diseases that can cause similar symptoms, such as parasites and more serious illnesses. Anti-inflammatory medication can be effective in treating it as can holistic remedies such as slippery elm. However, a diet change is often necessary to completely reduce symptoms.
Serious Causes
Bloody mucus in stool can rarely be an indicator of a more serious problem, such as stomach ulcers or certain types of cancer, especially those of the digestive system or colon. Diseases such as kidney and liver failure, pancreatitis and Addison's disease can also cause bloody stool.Viruses such as parvovirus or coronavirus can also cause bloody stool.
Usually, black and tarry stools are more indicative of internal bleeding but not always. If your dog is suffering from persistent, bloody stools, these illnesses may need to be ruled out through blood panels and possibly biopsies or X-rays.
Additional Causes
Blood and mucus in the stool can also have a mild cause, such as a cold, ingestion of a foreign body or hemorrhoids. The cause can often be determined by additional symptoms accompanying the bloody stool, but in the case of hemorrhoids, there may not be any other symptoms. In fact, it may take an X-ray to determine if your dog has ingested a foreign object that is causing a blockage.
If your dog has persistent bloody mucus in his stool, visit a veterinarian. Causes range from mild to serious, which makes it difficult to diagnose at home.