Dog Diarrhea: Causes and Treatment

1 Dog Diarrhea: Causes and Treatment

When your dog has diarrhea and needs to see a vet, describe its energy, appetite, habits, environment, vaccination and deworming history, and any other details. This information helps the vet pinpoint the cause, examine your pet, and confirm why the diarrhea is happening.

What causes diarrhea, and how should you handle it?

An occasional loose stool can come from eating something bad (such as spoiled leftovers), a sudden diet change, overeating, or stress, while the dog’s energy, appetite, and urination stay normal. The soft stool shows no blood, foreign material, parasites, or vomiting.

If your dog fits this picture, withhold food for a set period (over 6 months old: 6 hours; 6 months or younger: 4 hours) but keep water available, and give a pet-specific probiotic. After the fast, feed small, frequent meals of easily digestible food — softened kibble, a gastrointestinal prescription can, or plain boiled chicken breast with no salt or seasoning — with probiotics, returning to normal diet over two days. If everything returns to normal, it’s likely nothing serious.

If during this observation the diarrhea doesn’t improve, or the dog’s energy and appetite drop, vomiting appears, or these symptoms were present from the start, take it seriously — there may be another illness. Here is a breakdown.

1. Pathogenic microorganisms. In young or poorly vaccinated animals, sudden diarrhea can be viral — canine distemper, parvovirus, and coronavirus can all cause diarrhea, vomiting, fever, and low energy.

It can also be bacterial, such as overgrowth of Salmonella, Clostridium, or Campylobacter; these appear in normal dog stool too, but in limited numbers.

Fungal infection, including histoplasmosis, can also be a cause.

Roundworms, tapeworms, and other common parasites, as well as protozoa like coccidia and Giardia, can also cause diarrhea — especially in young animals.

2. Foreign objects

Bones, sticks, and other objects can lodge in the stomach or intestines, causing diarrhea and vomiting. As they pass through, they can also scrape the digestive tract and lead to diarrhea or bloody stool.

3. Allergies

Dogs can have food allergies — to a specific protein, grain, or additive — which also shows up as diarrhea and vomiting.

Also, poisoning from certain toxins (such as lead or pesticides) causes diarrhea, usually with vomiting.

4. Inflammatory bowel disease (IBD)

IBD is fairly common in both dogs and cats — a persistent inflammation of the gut. It has multiple causes: genetics, environment, diet, and infection. The most accurate diagnosis is histopathology (taking a gut tissue sample). Because it’s hard to confirm, it’s usually diagnosed by exclusion.

In some breeds IBD is congenital; for example, Basenjis can develop severe inflammatory bowel disease.

5. Tumors

Intestinal tumors are another cause, usually in older pets. Adenocarcinomas of the intestinal glands can be single, surgically removable masses or infiltrate the whole gut. Lymphosarcoma in dogs and cats may be single or multiple nodules, with abnormal lymphocytes spreading into the intestine.

6. Other diseases

Problems in other organs — kidney failure, liver failure, pancreatic disease — can all cause diarrhea.

Pancreatitis damages the pancreas so it can’t make enough enzymes to digest fat, causing exocrine pancreatic insufficiency and large, greasy stools. Congenital enzyme deficiency in young animals can cause this too.

How can you lower the chance of diarrhea?

Avoid sudden diet changes

Don’t give dogs bones (these can cause constipation or diarrhea)

Don’t let them play with very small objects

Don’t feed them table scraps

When out, stop them from eating random things (cat owners with leash-walking cats should watch this too)

Keep them dewormed and vaccinated on schedule (essential for both dogs and cats!)