16 Causes of Blood in Dog Stool
What's Causing Blood in My Dog's Stools?
Understanding Bloody Stools in Dogs
Seeing blood in your dog's stool can be a frightening event, perhaps because we often associate blood in stool with cancer. Luckily, in dogs the causes are often a lot less dramatic. Of course, as a responsible pet owner, it is always savvy to have the potential causes investigated by a veterinarian in order to rule out the more serious conditions.
Blood in stool is medically known as hematochezia or melena depending on whether the blood comes from the dog's lower or upper digestive system, respectively. It's important to recognize the differences between the two as they can mean a difference in your dog's diagnosis. Following are some ways to tell them apart.
In hematochezia, the blood in the dog's stool is bright red, meaning it is fresh and most likely deriving from the lower intestines, typically the colon or the rectum. It can be mixed in the dog's stools, or you can see a few droplets of blood as your dog defecates.
In melena, the blood in the stools causes feces to appear tarry and asphalt black, suggesting the blood is digested and possibly coming from the upper intestinal tract. Usually, but not always, melena is more worrisome than an occasional case of hematochezia. Melena is often not readily recognizable as hematochezia because dogs may often have dark stools and that doesn't necessarily mean they have blood in them.
Check Your Dog's Stool for Abnormal Signs
So how can you tell whether your dog's dark stools contain blood?
- Michael D. Willard, a board-certified veterinarian specializing in internal medicine, suggests placing the feces on absorbent white paper, such as a paper towel.
- Check for abnormal signs in your dog's stool and record your observations.
- Now, examine whether a reddish tint diffuses from the feces—if it does, that's proof that you're likely dealing with melena.
- If you find blood, the causes can be various and range from minor issues, such as dietary changes, to more severe causes, such as cancer or parvo.
Below are some common causes of blood in dog stool that you may want to have investigated by your veterinarian.
Dog Hematochezia vs. Melena
Bright red blood in stool
Tarry black stool
Derives from colon or rectum
Derives from esophagus, stomach, or upper small intestine
6 Causes of Fresh, Bright-Red Blood in a Dog's Stool
As mentioned, hematochezia is fresh, bright red blood in, or mixed with, your dog's stool. Unlike in humans, fresh blood in dogs is not indicative of hemorrhoids. The streaks of bright red blood in stool most likely come from the dog's rectum or colon. It’s best to have hematochezia investigated promptly by a vet, because some possible causes of the condition can be serious. Here are a few possible causes of hematochezia in dogs.
This is a serious virus often found in puppies. Black-and-tan breeds, such as rottweilers, German shepherds, and Dobermans are more prone to parvo. Typically, dog parvo symptoms include vomiting, diarrhea, lethargy, loss of appetite, and blood in stools. Because this disease can be deadly, puppies suspected of having parvo should be seen by a vet promptly.
Parasites are one of the most frequent causes of blood in the stool. The most common parasites that cause blood in the stool are hookworms, whipworms, and roundworms. Aside from blood appearing in your pet's feces, there are other clear signs and symptoms that indicate that your dog has worms. Protozoans such as coccidia may also cause bloody stools. A veterinarian can identify the offending parasites and prescribe specific dewormers to help get rid of these annoying beings.
3. Dietary Indiscretions
Overeating or dietary indiscretion may irritate a dog's colon, causing diarrhea and bloody stools, which can also have mucus.
Changes in the dog's diet can have similar effects. If you are switching your dog's food, do so gradually over the course of several days. If a diet change is done too suddenly, vomiting and diarrhea may take place. Even giving your dog a new treat or feeding him people food may cause an inflamed colon.
Other dietary causes of blood in the stool include eating spoiled foods and food intolerances or allergies.
Mild cases of stomach upset can be treated with these simple upset stomach remedies.
4. Hemorrhagic Gastroenteritis
Hemorrhagic gastroenteritis involves copious blood in stools along with vomiting and diarrhea. Often the cause cannot be found, but your dog may need intravenous fluids and proper medications to let this condition subside.
5. Rectal Injuries
If a dog ingests a stick, bone, or other sharp object, it may eventually scrape the lower intestinal lining or rectum as it makes its way out through the feces. Often, you might spot the object visibly protruding from the feces once it has worked its way through your dog's system. In such cases, the blood is bright red and will eventually stop.
Also, check for any rectal injuries, especially any involving the anal glands. Look for any localized swelling, injuries, or protrusions.
If the dog's stools are well-formed and have fresh blood on the surface, this can be indicative of the presence of a rectal polyp, which is an abnormal growth. When the stools pass over the polyp, which is highly vascularized, it will bleed. Sometimes you can see polyps protruding externally, but they can also be internal, in which case an endoscopy may be necessary in order to see it.
According to Merck Veterinary Manual, "The polyp can be felt by a veterinarian during a rectal examination, and its surface tends to bleed easily. Periodically, the polyp may protrude from the anus." All polyps should be checked out by a vet as sometimes they can be cancerous growths.
In some cases, blood in stool may be caused by stress. Stressful life events for a dog include changes such as a move, the addition of a new dog or family member to the household, and being boarded in a kennel. These events may cause a case of colitis with bloody diarrhea with mucus.
Causes for Melena, Dark Tar-Like Stools in Dogs
6 Causes of Black, Tarry Blood in a Dog's Stool
As mentioned, melena is the medical term for digested blood in the dog's stools, which causes them to appear black and tarry. Some dog owners describe such stool as looking like "coffee grounds." The blood may be originating from the dog's lungs, pharynx, esophagus, stomach, or upper small intestine. Because melena can be caused by serious conditions, including acute bleeding, it should also be investigated by a vet.
7. Use of NSAIDS
If your dog is on aspirin or some type of Non Steroidal Anti-Inflammatory drug like Rimadyl or aspirin, he may develop ulcers from its use. Dogs with bleeding ulcers will typically have black tarry stools meaning digested blood is coming from the stomach. Inform your vet promptly if your dog is on such medications, and always keep a watchful eye on his stools.
8. Blood Clotting Disorders
There are several canine conditions that may cause blood clotting disorders and bleeding. Affected dogs may also exhibit symptoms other than black tarry stools, such as purple-tinted skin, suggesting bleeding underneath the surface. Rat poison may also cause blood clotting disorders and bleeding, which may manifest as dark tarry stools. If you think your dog may have eaten rat poison, have him seen by the vet ASAP.
9. Post-Surgery Complication
If your dog has undergone some type of surgery recently and has black stools, call your vet immediately. There may be internal bleeding somewhere. This complication may appear up to 72 hours after the surgery.
Anytime your dog presents dark, blackish stools, have your dog seen. You want to rule out the possibility of bleeding tumors such as polyps or cancer, which can be quite common in elderly dogs.
On a lighter note, if you have recently given Pepto-Bismol to your dog, the medication may temporarily turn stools black. This potential side effect is actually written on the bottle if you read it. When you stop giving it, the stools should soon shortly turn back to normal.
*Disclaimer: Pepto-Bismol can cause gastric bleeding. It should only be given if recommended and overseen by a veterinarian.
12. Ingestion of Blood
A dog's stool may also appear black and tarry from ingesting blood. For instance, your dog may have licked a bloody wound, or he may have had a mouth injury or nose bleed causing him to swallow blood. Because the blood may also come from a bleeding ulcer, it's important to see your vet if you see dark stools and cannot find an explanation.
As seen, there are many possible causes of blood in stool. The ones listed above are not the only possibilities. Others include:
16. Bacterial infections, such as those caused by campylobacter or clostridium perfringens
Slippery Elm Bark Remedy for Dog Diarrhea and Bloody Stool
Slippery elm bark works well for many health issues with dogs, including diarrhea that causes hematochezia (bloody stools), which can happen with colitis. I have a dog who comes for boarding that gets stress colitis with bloody stools, and we use GastroElm Plus during his stay.
is made with 80% slippery elm bark powder, and is intended for use with pancreatitis in dogs, ulcers in horses, as well as vomiting, diarrhea, and other gastrointestinal problems in cats, dogs, or horses. It is formulated and manufactured in the U.S. using the finest human-grade herbs available. GastroElm Plus
What to Do If Your Dog Has Blood in His Stool
• See your vet if your dog is pooping blood. If your dog has pale gums, becomes lethargic, vomits, or has diarrhea, see the emergency vet at once.
• Bring along a fecal sample so your vet can immediately start ruling out parasites and protozoans. The stool sample needs to be no more than 12 hours old to grant testing accuracy.
• If you're dealing with colitis, you can ask your vet about trying a brief fast followed by a bland diet.
Disclaimer: This article is not to be used as a substitute for professional veterinary advice. If your dog is pooping blood, see your vet to rule out serious medical conditions. By reading this article, you accept this disclaimer.
Does your dog have bloody stools?
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
Questions & Answers
My chihuahua vomited foam last night. This morning, he had a runny tummy with blood. He died at 9 p.m. What could have caused his death?
Could your dog have had a platelet disorder where he could not clot his blood? Could your dog have gotten in contact with some kind of poison? Rat bait can cause internal bleeding and blood in the diarrhea. There are so many possibilities, only a necropsy done at the vet may provide you with answers. So sorry for your loss.Helpful 135
My pit is twelve-years-old. There was a red tint to his bowel movement today. It was runny with a dark color to it; he is not vomiting. He has been drinking a lot of water. Not finishing all of his food when I feed him. And his paws are cold to the touch. Dry nose. No energy? He lives inside. Watched him closely, so he hasn't eaten anything out of the norm.
Your pit's symptoms sound worrisome. The cold paws, no energy can be indicative of internal bleeding. I suggest you take your dog to the vet as soon as you can. At this age, one big concern would be a bleeding tumor.Helpful 83
My dog is a year old, and she doesn't eat anything besides water. Her stool is red and watery, and she's stopped barking. What is wrong with her?
Your dog's symptoms are concerning. The reduced barking maybe because she's not herself and feeling ill. There are too many differentials when it comes to bloody stools in dogs, and therefore, seeing the vet is a must for a proper diagnosis and treatment. Bring in a fresh stool sample along to your vet appointment.Helpful 82
After my dog poops, I wipe him with a baby wipe. Today there was blood from his rectum, though I noticed he been scooting on the rug and constantly looking towards his back end. What could it be?
If your dog has been scooting, this can be indicative of an issue with the anal glands. Anal gland issues are known to cause issues when they do not empty as they should, and this can lead to local irritation, infection and even an abscess. The blood can be from friction with the carpet or a ruptured anal gland. In this latter case, you would notice a lump or red looking "wound" under the tail right around the rectum at the 4 o'clock or 8 o'clock position. However, there can be several other things going on. You should have your vet check your dog to pinpoint the problem.Helpful 68
There are no vets or animal hospitals open, and my dog had dark red blood in his watery black stool. Will he be okay until Monday when they open? I don't know what to do.
It is hard to say because there are so many possible causes for blood in a dog's stool. Particularly concerining are pale gums, lethargy, weakness and slow capillary refill time. There should be an emergency vet in your area open if things appear concerning.Helpful 65
© 2008 Adrienne Farricelli