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 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
Common Causes of Fresh, Bright-Red Blood in 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 of the 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. Avoid giving your pet sticks or cooked bones to play with. If your dog has already ingested it, try feeding him some high-fiber bread or rice to help him pass the bone.
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.
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
Causes of Black Tarry Blood in 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.
1. 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.
2. 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.
3. 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.
6. 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:
- Intestinal blockages
- Cancerous masses
- 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?
Questions & Answers
I have a three-month-old dog. He's not eating, and his stool is red and watery. Is it possible that he's gonna die?
I am so sorry your puppy is not eating, and his stool is red like water. Death from a severe disease like Parvo is possible. You should see your vet as soon as possible. There are chances that Parvo (or any other condition your puppy may be suffering from) can be treated if you get help soon.
My puppy has diarrhea with blood in it, but he’s still eating, drinking and playing. Should I be worried?
This would be something to keep an eye on. It could be just a case of colitis. But because puppies can get parvo, (especially those who weren't vaccinated or haven't finished their series of booster shots), and other worrisome conditions like HGE or coccidiosis, you are better seeing your vet if this persists, or if your puppy seems not to be doing well. On top of that, consider that with diarrhea, your puppy can get dehydrated quite quickly.
My lab is 1.3 months old. And he just pooped, and there was blood in that. What could be the cause? He is vaccinated against Parvo too.
There are many possibilities. Blood in a dog's stool is not pathognomonic (specifically indicative) of any one particular disorder but several. Your vet is the best person for diagnosis.
I have a 10-month-old female Westie. She just came out of heat. Her stool is black, and she won’t eat. It has been eight days. What’s wrong with her? I took her to the vet, and they did x rays and blood work and tested her for other diseases. They found nothing.
This may be one of those medical mysteries. Black stools in dogs can be a sign of internal bleeding or a bleeding ulcer. Some dogs get black stools when exposed to rat poison. It may be worth seeking a second opinion by another vet or pursuing more testing as your dog sounds like she's doing poorly and not eating well. A referral to a specialist in internal medicine may also be insightful.
© 2008 Adrienne Janet Farricelli