Bloody Diarrhea in Dogs:
When to Worry and What to Do

Call the vet first

Bloody diarrhea can be a serious concern, and your dog should see the vet as soon as possible. Depending on the cause, it may not be good to wait. Some of the conditions behind it move fast and need fluids or medicine the same day; others are milder. Only an exam can tell you which one you're looking at.

It helps to notice a few things before you go: when it started, how many times it has happened, whether there is vomiting too, and whether your dog could have eaten something they shouldn't. If you can, bring a photo or a sample.

What the color can tell you

Bright red blood is fresh. It usually comes from the lower gut, the colon or rectum, and you may see it as streaks, red mucus, or drops at the end. It looks alarming but isn't always a sign of something life-threatening.¹

Black, tarry stool is blood that has been digested on the way through. It usually points higher up, to the stomach or small intestine, and is the more concerning of the two. Dark food can darken stool too; wiping it on a white paper towel and looking for a dark red tinge is one way to tell.¹

When it is an emergency

Go now, or call an emergency clinic after hours, if you see any of these:

• Vomiting as wellSudden vomiting with bloody diarrhea is the classic picture of HGE, and dogs can lose fluid quickly.²
• A lot of blood, or jelly-likeLarge amounts of blood, diarrhea that looks like raspberry jam, or blood with no stool at all.^1,2
• Black, tarry stoolA sign the bleeding may be in the stomach or upper intestine.¹
• A puppy, or a dog who is flatPuppies and unvaccinated dogs are most at risk from parvovirus. Weakness, a dog who won't get up, or one who won't eat is a reason to hurry.³

What can cause it

There can be quite a variety of causes, whether or not vomiting comes with it. These are some of the most common, though the list is not complete:

• HGE, hemorrhagic gastroenteritis, now called acute hemorrhagic diarrhea syndrome²
• Parvovirus or coronavirus³
• Intestinal parasites
• Something swallowed that shouldn't have been
• A viral or bacterial infection
• Colitis, inflammation of the large intestine⁵
• Toxins, or something poisonous eaten
• Stomach or intestinal ulcers
• Addison's disease (hypoadrenocorticism)
• Gastrointestinal cancer

HGE deserves its own mention. It comes on suddenly, often in a small or toy breed that seemed perfectly healthy, with vomiting and a large amount of bloody diarrhea. The main treatment is prompt IV fluids at the clinic, and dogs seen early usually do well.²

What the vet will look for

Because so many things can cause it, finding the answer can take a few steps. Most vets start with a stool sample for parasites, a parvo test for puppies and unvaccinated dogs, and bloodwork; with HGE, the red blood cell count often comes back very high because the dog has lost so much fluid. If something swallowed or a growth is a possibility, X-rays or an ultrasound may follow.^2,4

If the answer your vet comes up with doesn't seem solid to you, consider a second opinion, just as you would for something serious in yourself.

Where Nzymes can help

Nzymes doesn't treat the cause of bloody diarrhea. That is the vet's job, and sometimes it is urgent. Where we can help is afterward, when the gut is trying to recover: putting back the beneficial bacteria an upset like this washes out, and giving the body the live-food enzymes and antioxidants it needs to rebuild.

The Core FoundationSee the Core Foundation →Sprouted Granules in the bowl and Antioxidant Treats by hand: live-food enzymes and antioxidants, made from live sprouted soybean meal. Where every dog starts.

Bac-Pak PlusFive live probiotic strains plus eight digestive enzymes, to restore and protect the beneficial bacteria in the gut. Ox-E DropsFor immune assistance: a few drops a day to support healthy pH and oxygen balance from within.

Not sure what fits your dog once the vet has a diagnosis? Book a free consultation and tell us what they found. Diet is the first thing we'll go over; our recommended foods guide shows what to look for.