The presence of blood and mucus in a dog's stools usually indicates some sort of infection, parasitic infestation or other health condition. Although you should always consult your vet if a situation like this arises, it's helpful to understand what can cause this problem and what you should do for your dog in this situation.
Possible Causes for Blood and Mucus in Dog Stools
Irritable Bowel Syndrome (IBS)
IBS, also referred to as colitis, is caused by irritation and inflammation in the large intestine, and it can produce both blood and mucus in the stools. IBS can be brought on by other primary causes such as whip worm infestation or a change in diet.
Chronic diarrhea Is a long-term condition that is often accompanied by blood and mucus, and it can be caused by a number of health issues, including intestinal blockages, parasitic and viral infections, cancer, pancreatic disease and more. This makes it difficult to narrow down the exact cause of the diarrhea.
Parvovirus attacks the lining of the gastrointestinal tract and produces large amounts of diarrhea loaded with blood and mucus. Coronavirus also produces blood in the stools, but there is a distinct lack of mucus with this particular virus.
Giardiasis is a condition is caused by a single-celled organism that invades a dog's intestines. It produces chronic diarrhea and stools filled with fatty mucus.
Foreign Body/Bowel Obstruction
Dogs tend to eat a lot of things they shouldn't, and any object that can't be dissolved in the digestive system has an opportunity to cause a blockage in the stomach or intestinal tract. Straining and irritation can lead to bloody stools as well as mucus that is produced as a reaction to the irritation.
Colon cancer can present some of the same symptoms as IBS, so it's sometimes overlooked when searching for the cause of the blood and mucus. Watch for weight loss as well.
Liver disease affects the production of proteins that support blood clotting, and this can lead to blood in the stools in some instances. It's also possible to mistake bleeding caused by liver disease for a bleeding ulcer, which can also produce dark, tarry stools.
Hematochezia and Melena
The color and consistency of the blood in the stools tells the vet determine whether the blood originated in the upper or lower portion of the digestive system. This information helps the vet form an accurate diagnosis and treatment plan.
According to Pet MD, hematochezia is the term used to describe the presence of fresh red blood in the stool. This means the source of the bleeding must come from somewhere in the lower gastrointestinal tract. Hematochezia may be an indication of a serious health problem, or it could be something very minor. If the bleeding happens only one time, it is considered a transient event and is usually nothing to worry about. If the bleeding continues, becomes more severe or keeps recurring, take the dog to a veterinarian to determine the cause.
Some of the more common causes include:
- Infectious agents
- Bacterial infections including salmonella and clostridium
- Colitis or proctitis
- Overeating, eating food that has gone bad or eating bones and other foreign material
- Allergies to certain foods
- Cancerous tumors or benign polyps in the rectum, colon or anus
- Bleeding disorders
- Inflammation of the anal sacs
- Injuries and trauma such as a fractured pelvis or a bite to the anal area
Melena is the term used to describe when a dog passes digested blood, so the blood passed through the upper digestive system first. The stools are shiny, sticky and black; they have the consistency of tar and smell very foul.
There are many causes of melena and most of them are very serious. The first thing your veterinarian must do is rule out the possibility of the digested blood coming from a wound the dog was licking or swallowing blood from its respiratory tract or mouth.
Some of the most common causes of melena include:
- Gastrointestinal tract diseases causing ulcerations and bleeding
- Clotting abnormalities and bleeding disorders
- Drugs such as nonsteroidal anti-inflammatory agents and corticosteroids causing ulceration of the intestine
- Tumors in the gastrointestinal tract
- Twisting of the stomach
- Severe infections
- Addison's disease
- Toxicity from heavy metal including arsenic, zinc and lead
What You Should Do
It's never a good idea to ignore the presence of blood and/or mucus in your dog's stool since it can be caused by so many conditions that truly require treatment. If you find yourself in this situation:
- Collect a sample of the stool in a zip lock bag.
- Call your vet, explain what's going on, and make an appointment to bring your dog in for an exam.
- Your vet will perform a fecal examination of the stool sample to check for the presence of worms or worm ova, as well as any other clues to the cause of the stool's condition.
- The vet may decide to perform further tests based on the initial exam. Depending on your dog's symptoms, these may include an ultrasound or x-ray, complete blood count, urinalysis, colonoscopy or any other tests deemed necessary to reach an accurate diagnosis.
Resist the urge to panic. Many conditions that cause blood and mucus in stools are reasonably easy to treat, such as worms and giardiasis. Even cases of parvo or corona can be managed with early detection. The key is to contact your vet right away before your dog's condition has a chance to deteriorate.