Dog Vomiting and Diarrhea: When to Call the Vet, and When It Can Wait

It's 11pm, your dog just threw up on the kitchen floor for the second time, and now there's a loose stool by the back door too. He's still wagging when you walk in. Does that mean it's fine, or does two symptoms at once change the math?

It changes it. Cornell's veterinary school lists vomiting on top of diarrhea as one of the reasons to get a vet involved, and the two together dry a dog out faster than either one alone. That doesn't always mean the emergency room tonight. Often it means a phone call.

The signs that mean don't wait

Call now, regardless of the time, if you see blood in the vomit or stool, or vomit with the look of coffee grounds (that's digested blood, and Cornell's veterinary school lists it as a reason to get seen, not to watch and wait). The same goes for black, tarry stool, what vets call melena, which is partially digested blood that can come from higher up the gut than the diarrhea itself suggests. Cornell is just as direct about lethargy, a fever, a painful or swollen belly, or vomiting that's gone on past 24 hours. Any of those means call the vet.

One combination deserves its own line. Repeated retching with nothing coming up, especially alongside a stomach that looks swollen or distended, is an early sign of bloat (GDV) according to VCA Animal Hospitals, and that's a different, more urgent emergency than ordinary vomiting. It needs a vet immediately, not a wait-and-see window.

If there's any chance he ate something toxic, don't wait for symptoms to develop. Call your vet, or the ASPCA Animal Poison Control Center at (888) 426-4435, which answers 24 hours a day (a consultation fee may apply). Senior dogs and dogs with an existing health condition dehydrate faster than a healthy adult, so give them a much shorter wait before you call.

If any of that matches what you're looking at, the rest of this article isn't for tonight. Go.

If it's a puppy, skip the watching

A puppy with vomiting and diarrhea is a different situation from an adult dog with the same two symptoms. Parvovirus causes both, often with bloody diarrhea, a fever, lethargy and a puppy who won't eat, and the American Kennel Club notes that unvaccinated puppies between 6 weeks and 6 months old are the most vulnerable. The AKC's advice is to consult a vet as soon as a puppy seems unwell rather than waiting it out, because puppies can decline fast.

If parvo is a possibility, phone first. PDSA, the UK veterinary charity, tells owners to say they think it might be parvo and to wait outside until they're called in, so the virus doesn't reach other dogs in the waiting room. The home routine further down this page is written for adult dogs, not puppies.

What a wait-and-see case actually looks like

Most nights aren't that. Dr. Meredith Miller, an associate clinical professor of small animal medicine at Cornell, puts it plainly: many cases of diarrhea in dogs are "mild and self-limiting." Cornell's guidance on vomiting says something similar. An isolated episode, especially something like throwing up right after eating grass, is usually just that. Isolated.

So the true watch-and-wait case is narrower than most owners assume. One vomit, or one loose stool, or one of each close together, and then he goes back to being himself: eating when food is offered later, drinking, interested in what's going on around him, not hiding under the bed. If the vomiting and the diarrhea keep coming, even with the tail still going, that's the combination Cornell says to bring to a vet. A call to your clinic is a reasonable first step, and they'll tell you whether he needs to come in.

Cornell also flags the dog who vomits even once a week, week after week. That pattern may point to an underlying disease, however normal he seems in between. It isn't tonight's emergency, but it is worth a regular appointment.

What usually causes both at once

When the stomach and intestines are inflamed, vets call it gastroenteritis, and vomiting with diarrhea is its classic pair of signs, as VCA Animal Hospitals explains. The everyday causes on Cornell's list for diarrhea are eating something he shouldn't have (the trash, something found on a walk, a rich scrap from the table), a sudden switch to a new food, stress such as boarding or a vet visit, and intestinal parasites.

The same list has a serious end too, including viral infections like parvovirus, a swallowed object blocking the gut, toxins, pancreatic disease, Addison's disease and liver disease. You can't tell those apart at home, and nobody expects you to. That's what the warning signs at the top of this page are for. If you see one, let the vet sort out the cause.

Why the combination is worse than either symptom alone

This is easy to miss if you think about vomiting and diarrhea separately. Your dog's gut normally pulls water back into the body as food moves through. Diarrhea breaks that. Everything moves too fast, and water leaves the body along with the waste instead of being reabsorbed. That alone can add up to dehydration over time.

Add vomiting on top, and there's no second chance to take in fluids to make up for what the diarrhea is losing. Cornell's material on canine diarrhea is explicit that vomiting on top of diarrhea "further accelerates dehydration." And dehydration is what actually turns a digestive upset into a medical problem, by throwing off electrolyte balance and putting extra strain on the kidneys. That's the real reason "he's got both" is a different, more urgent question than "he's got one."

How to check for dehydration at home

Since dehydration is the real risk, it helps to know what it looks like. Dr. Jerry Klein, the AKC's chief veterinarian, describes three quick checks. Gently lift the skin near his shoulder blades and let it go, then watch how quickly it settles back into place. Touch his gums, which should feel wet rather than sticky and dry. Then press a fingertip gently against the gum and watch how fast the color comes back once you lift it.

Skin that's slow to settle, tacky gums, or color that's slow to return are all signs he's losing more fluid than he's taking in. With vomiting and diarrhea both going, any one of them is a reason to call. It's worth trying the checks once on an ordinary healthy day too, so you know what normal feels like on your own dog before you ever need to compare.

What to do while you decide

None of this treats anything. It's just what keeps a mild case from turning into something worse while you watch, and it's for adult dogs. For a single, isolated episode, Cornell's guidance is to withhold food, not water, for about 12 hours. Water stays available the whole time, since dehydration is the actual risk here, and cutting off water doesn't help anything. After that window, ease back in with a bland diet, plain boiled chicken and plain white rice, nothing seasoned, for two days, rather than going straight back to his normal food. Small portions spread through the day go down easier than one full bowl; VCA describes the diets vets prescribe for gastroenteritis the same way, as small, frequent, low-fat meals.

Write down when it started, what he ate in the last 24 hours, and how many times it's happened. Note whether he heaved before the vomit came up, too. Cornell separates vomiting, which comes with retching, from regurgitation, which comes up with no warning and can point to a problem in the esophagus instead. That detail is worth more to a vet on the phone than almost anything else you can tell them. And don't reach for a human anti-diarrheal or anti-nausea medication unless a vet has told you the dose for your specific dog. What's safe for a person isn't automatically safe at dog-sized doses.

If the vomiting or diarrhea is still going after that window, or either one gets worse instead of better, that's the point to call, not more waiting.

The dividing line, in one place

Go now for blood in the vomit or stool, black tarry stool, retching with nothing coming up, a swollen or painful belly, lethargy, a fever, a puppy, or anything toxic he might have eaten.

Call the vet today for vomiting and diarrhea that keep repeating, vomiting past 24 hours, diarrhea past 48 to 72 hours, or any sign of dehydration.

Watch closely at home only after one episode of each, followed by an adult dog who's eating, drinking and acting like himself. Keep water down and offer a bland diet.

FAQ

Is it normal for a dog to vomit and have diarrhea at the same time?
It happens, and it isn't automatically an emergency, but it deserves more attention than either symptom alone, because the two together dehydrate a dog faster than one would on its own. Watch for how your dog is acting, not just the symptoms themselves.

That same rule, watch behavior more than any single symptom, is the whole subject of How Do I Know if My Dog Is in Pain?, which covers the quieter signs beyond digestive upset.

My dog is vomiting and has diarrhea but is acting normal. Should I worry?
Acting normal is good news, but it isn't the whole answer. If it was one episode of each and he's back to eating and drinking, watching at home is reasonable. If it keeps happening, Cornell's guidance is to involve a vet even though he seems fine, because the fluid he's losing keeps adding up whether or not he looks unwell.

What would make a dog throw up and have diarrhea?
Most often something he ate, a sudden change of food, stress, or parasites. Less often it's an infection like parvovirus, a swallowed object, a toxin, or a problem with the pancreas, liver or adrenal glands. Any of the warning signs at the top of this page means let a vet work out which it is.

How long can dog diarrhea last before it's a vet visit?
Cornell's guidance points to 48 to 72 hours as the outer edge for a case that's otherwise mild. If he's vomiting too, or he stops eating or seems lethargic, don't wait for that clock to run out. Call sooner.

My dog has had vomiting and diarrhea for 3 days. What should I do?
Call the vet today. Three days is past Cornell's 24-hour line for vomiting and at the far edge of its 48 to 72 hours for diarrhea, and with both going for that long, dehydration is a real concern even if he still seems himself.

My puppy has vomiting and diarrhea. Can I wait it out?
No. Puppies dehydrate quickly, and the same two symptoms are how parvovirus shows up in young or unvaccinated puppies. Call your vet now, and tell them on the phone if parvo is possible so they can keep other dogs away from yours.

Should I feed my dog or give water while I wait?
Keep water available the entire time. For an adult dog with a mild, isolated case, Cornell recommends withholding food (not water) for about 12 hours, then easing back in with plain boiled chicken and rice for two days before returning to his normal food.

That's the same kind of decision our Dog First Aid guide walks through for the situations that show up most, so you're sorting go-now from watch-and-wait before the bad night happens, not during it.

Related reading: Is My Dog's Limping an Emergency, or Can It Wait?

Related reading: How Do I Know if My Dog Is in Pain?

Related reading: Why Does My Dog Whine and Pace in the Car?