Vet Reviewed

By The Farmer's Dog | November 11, 2023

  • No matter your dog’s age, diarrhea is not normal.
  • Most cases of diarrhea are no big deal, and they often resolve on their own.
  • If your dog’s diarrhea lasts more than a day or two, they need to see a vet ASAP.
  • Dogs who won’t eat, are vomiting, or have blood in their stool need to see a vet right away even if they’ve only had diarrhea once.


Dogs, like humans, change as they get older. Some of those changes can make them more vulnerable to gastrointestinal issues.

But even if your dog is a senior, diarrhea is not normal. If you notice that your dog has loose stool that lasts for more than a day or two—and if they show certain other signs, including lack of appetite, vomiting, or blood in their stool—you should bring them to your vet as soon as possible. That’s the headline, but here is some more information about diarrhea and what to do if your senior dog has it.

What is diarrhea?

You probably know diarrhea when you see it, but a loose definition of the term is frequent discharge of liquid feces. Usually, a dog with diarrhea will defecate more frequently than one with normal bowel movements.

Why your senior dog might have diarrhea

Diarrhea is not a disease, but can be a sign of one.

A veterinarian is best qualified to figure out why your senior dog has diarrhea. Possible causes range from conditions that are self-resolving and no big deal to, less commonly, diseases that can be life-threatening.

Here is a non-exhaustive list of reasons dogs may get diarrhea:

  • Dietary indiscretion
  • Allergies
  • Food intolerances
  • Parasites
  • Infections
  • Kidney disease
  • Liver disease
  • Addison’s disease
  • Inflammatory bowel disease
  • A change in diet 
  • A reaction to a medication
  • Stress
  • Poisoning
  • Ingestion of a foreign body, including one that causes an obstruction
  • Cancer, though this is not among the most common reasons
  • Pancreatitis

One of the most common causes of diarrhea that vets report in city dogs is related to gastrointestinal parasites, transmitted through fecal-oral contamination. If your pet is eating feces or sniffing poop on the sidewalk, they are at a much higher risk of picking up one of these parasites. You should give your dog lots of opportunities to sniff on walks—smell is a dog’s most important sense—but keep them away from unknown foods, fecal matter, and other items that could be dangerous if they lick or ingest them.

Context can be important as you try to weigh how threatening the source of your dog’s diarrhea is. If you know that your dog grabbed some dog-safe human food off of your plate and ate it, or that they’ve had a stressful day, you might infer that those are likely reasons for some mild diarrhea. If they were out of your sight in an unfamiliar area near dangerous objects or substances, it’s more likely that they ingested something that could call for urgent action. When in doubt, call your vet.

When to bring a senior dog to the veterinarian for diarrhea

Whether your dog is a senior or not, their diarrhea may get better on its own. But if it’s been more than a day or two and their bowel movements still aren’t normal, call your vet.

There are also warning signs that, even if your dog has just started experiencing diarrhea, it’s an emergency and you need to get them to the vet right away. These include:

  • Blood in the diarrhea, including black or tarry-looking matter that can be dried blood
  • Unwillingness to eat or drink, or a loss of appetite
  • Lethargy (sluggishness) or other behavioral changes
  • Vomiting

To repeat: if your dog has diarrhea for more than a day or two, no matter what, you need to bring them to the vet. Not only can this be a sign of a serious condition that requires immediate treatment, but the diarrhea on its own can cause dehydration whose consequences, if untreated, can include death. 

What a vet will do if you bring your senior dog in with diarrhea

If you bring your senior dog in for a vet visit due to their diarrhea, your vet will probably start by asking you some questions and performing a physical examination. They will likely want to test a stool sample, so bring one in if you can. They may also take a blood sample or perform imaging tests like X-rays or ultrasounds.

Based on the information they gather from these sources, the veterinarian will work with you to create a treatment plan.

How to treat diarrhea in a senior dog

Treatment of diarrhea in a senior dog will vary depending on the reason for the diarrhea.

Obstructions must be removed, and particular drugs may be effective against causes like parasites. Dogs with diarrhea will often require subcutaneous or intravenous hydration to make up for the water and electrolytes they’ve been losing. If the vet gives your dog antibiotics to treat the cause of their diarrhea, they may also prescribe a probiotic to help them restore healthy gut flora. Don’t give your dog any medication without consulting a veterinarian first.

Your vet may recommend withholding food for 12 to 24 hours. If you do this, never withhold water—it’s important that your dog be able to drink so that they can stave off dehydration. After the short fast, a veterinarian may prescribe a temporary switch to a bland or home-cooked diet, with ingredients like plain chicken and rice. While a diet like this could cause malnutrition in the long run, sometimes feeding it to a dog in the short term can help settle their stomach. 

Other home remedies that can help with some cases of diarrhea include bone broth and small amounts of plain, unsweetened pumpkin (never use pumpkin pie filling, or pumpkin with any added ingredients). These home remedies are okay to try if your vet has advised you to do so, or if your dog has a mild case of diarrhea that you’re sure is caused by something relatively non-threatening, like an ill-advised chomp on some non-poisonous human food. But if you think there’s any chance that the culprit could be something more serious, do yourself and your dog a favor and go to your veterinarian so that they can weigh in.