Canine Diarrhea
Diarrhea in dogs can be acute or chronic, and can be an indication of various possible health issues, from digestive problems to poisoning. This page looks at the likely causes and different characteristics of diarrhea that can happen in dogs.

Depending on the diet of an individual dog, most healthy dogs go “poop” once or twice a day. Understandably, a normal stool does not contain any mucus, blood, or undigested food.

Diarrhea refers to the passing of loose and unformed stools. Usually, in diarrhea, there is a large volume of stool, and the dog has to go to the bathroom more frequently than usual.

Diarrhea can be acute or chronic.

Acute diarrhea in dogs comes on suddenly and is over in a short period.

Chronic diarrhea comes on gradually and persists for a long period of time, e.g. three weeks or longer, or has a tendency to recur.

Most cases of canine diarrhea are temporary acute diarrhea with watery, foul-smelling stools. This is likely the result of foods moving rapidly through the bowel and arriving at the rectum in a liquid state. It’s mostly caused by eating inappropriate foods.

Canine Diarrhea Causes

Different Characteristics of Canine Diarrhea

Generally speaking, diarrhea can originate in the small bowel or the large bowel, depending on the cause.

Diarrhea originating in the small bowel has different color and consistency than that originating in the large bowel.

Though it’s not exactly an appetizing topic, but if we familiarize ourselves with the different characteristics of dog diarrhea, we are in a better position to know where the possible problem is from.

Here is a quick reference of the different characteristics of canine diarrhea:

Color Possible Causes Possible Location
Yellow, greenish Food intolerance; dietary indiscretion; upper GI tract inflammation Small bowel
Black, tarry Bleeding in upper GI, e.g. stomach ulcers Stomach or small bowel
Red fresh blood or clots Bleeding in lower GI Colon
Light colored Liver problem, e.g. lack of bile Liver
Gray colored, rancid smell Inadequate digestion Small bowel

Consistency Possible Causes Possible Location
Watery Food intolerance; dietary indiscretion; upper GI tract inflammation Small bowel
Foamy Bacterial infection Small bowel
Jelly-like with mucus Large bowel disorder, e.g. colitisIBD Colon

Diarrhea with Other Issues Possible Causes Possible Location
Weight loss Digestion or absorption problems Small bowel, pancreas
Normal appetite, no weight loss Large bowel disorder Colon
Vomiting GI tract infection, e.g. bacterial infection, poisoning Small bowel

What Causes Diarrhea in Dogs?

Sudden onset of acute diarrhea can be caused by:

Dietary Indiscretion

Dogs who have eaten something that they shouldn’t have, such as garbage, spoiled foods, and indigestible things like plastic, wood, paper and so on, will pay the price of having diarrhea later on!

Food Intolerance/Allergy

Food intolerance in dogs is similar to that in people, such as lactose intolerance. They react by developing diarrhea, usually just for a short time.

Food allergies in dogs, on the other hand, can cause a lot of symptoms besides diarrhea. The most prominent one is intense itching.

Depending on the individual dog, some foods that cause intolerance or even allergic reactions include beef, pork, fish, eggs, chicken, corn, wheat, soy, fats, milk, and so on.

Ingestion of Poisons

Dogs who have ingested foods or substances that are poisonous to them, e.g. antifreeze, grapes, will also have diarrhea.

Depending on the poison ingested, the dog will show other symptoms, such as panting, drooling, or even seizures.

Sudden Change of Food

Sudden, abrupt change of food can cause a dog to react adversely by having diarrhea.

If you want to change your dog’s food, do it gradually over a period of one week or more. Start by substituting 10 percent of his existing food with the new food, then gradually increase the new food to 30 percent, then 50 percent, and so on.

This gradual change gives the dog’s digestive system enough time to adjust to the change.

Intestinal Parasites

Intestinal parasites (such as hookworms, roundworms, Giardia, etc.) can cause digestive issues, such as diarrhea and vomiting.

Usually, dogs with parasites are weak and lethargic, and will gradually lose weight.


Bacterial and viral infections (e.g. canine parvovirusdistemper) also cause a dog to have diarrhea. These infections can be particularly dangerous in puppies.

Dogs with an infection usually have other symptoms, such as having a fever and no appetite. They are weak and lethargic and don’t want to play.

Side Effect of Medication

Some drugs and medications (e.g. NSAIDs, antibiotics, dewormer, and some heart medications) can cause diarrhea in dogs.

Psychological Issues

Stress, excitement, or anxiety, e.g. after boarding at kennels, can also cause diarrhea in dogs.

Chronic diarrhea can be caused by:

  • Poor-quality food.
  • Intestinal parasites.
  • A compromised immune system.
  • A weak gastrointestinal system.
  • Other more serious underlying health issues (such as colitis, inflammatory bowel disease, kidney and liver diseasepancreatitis, or stomach cancer).

How to Treat Canine Diarrhea

Since diarrhea is a symptom, usually caused by an underlying health issue, treatment of diarrhea involves finding out and treating the underlying cause.

If your dog has a bout of acute diarrhea but is otherwise healthy, you can try fasting the dog for 12 hours to see if the diarrhea goes away. Be sure to encourage your dog to drink enough clean water during fasting to prevent dehydration.

You may also want to use some simple home remedies to help make the dog feel better. Visit our post on Dog Diarrhea Cures to see how.

Note, however, if your dog’s diarrhea does not improve in 2 days, it’s time to take him to the vet for a checkup.

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