Primary Causes of Dog Diarrhea and Vomiting

Dog diarrhea and vomiting are two symptoms that can go hand in hand. Diarrhea and vomiting can signal a severe illness, but it may also be a sign of an upset stomach. Occasional vomiting is normal; however, if your pet has chronic vomiting and diarrhea, you have to visit the vet.


Gastroenteritis is an inflammation of the stomach and small intestinal lining. This is the most common cause for vomiting and diarrhea in dogs. Gastroenteritis may be caused by viruses, bacteria, fungi, parasites or even certain food ingredients.

Food Intolerance

Food intolerance can cause vomiting and diarrhea in dogs. The dog's body will try to eliminate the food that doesn't agree with its system.

The food needs to be identified by food testing and possibly eliminated from the dog's diet. Prescription food may be recommended for dogs that have several food intolerances.

Note that food intolerances are different from food allergies. Food allergies will show symptoms such as itchy skin and dermatitis, and are typically more severe.

Intestinal Parasites

Vomiting and diarrhea can be caused by intestinal worms such as tapeworms, hookworms, roundworms, coccidia or giardia. You may also notice worms or worm segments in the feces. Intestinal parasites are highly contagious, but are treatable with doses of dewormers.


Vomiting and diarrhea are symptoms of numerous bacterial, viral and fungal infections.

Common bacterial diseases that cause vomiting and diarrhea include Salmonella or Clostridium perfringens.

Parvovirus infections are more common in puppies and may be prevented by vaccination. Dogs with parvo will vomit and have bloody, watery stools.

Fungi (especially yeast or Candida Albicans) affect the dog's intestine and stomach lining, and can also cause vomiting and diarrhea.

Dietary Changes

A recent change in your dog's diet may lead to throwing up and diarrhea, especially if the transition was abrupt. You need to allow your dog to transition to a new diet by gradually introducing a few elements of the new diet per month. Talk to your vet about the best way to make the transition easier.


Dogs may ingest different objects, plants, chemicals or garbage. Poisoning can occur when the dog has ingested a toxic ingredient. The dog will start to throw up and later have diarrhea. Ideally, you should take the dog to the vet when you notice he has ingested something toxic.

Dogs may get poisoning from alcohol, chocolate, human drugs, xylitol or chewing gum, raisins, rat poison or toxic plants.

Heat Stroke

Dogs cannot stay in the sun or hot temperatures, or they may get heat strokes. Vomiting can signal heat stroke and may be followed by seizures. A heat stroke can be fatal, so you need to decrease your dog's body temperature immediately.

Additional Tips

  • Vomiting and diarrhea may also be caused by diabetes, cancer, ulcers or liver disease.
  • It's important to prevent dehydration, as in weaker dogs this can be fatal.
  • If the vomiting and diarrhea lasts for more than 48 hours, or if you notice blood in the stool or vomit, call your vet.
  • In case your dog is poisoned, you need to visit the vet right away.