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Gastroenteritis in Dogs: Causes, Diagnosis, and Treatment Options

Doggie diarrhea is nobody's idea of a good time. Knowing how to recognize gastroenteritis will help you get your dog treated for this icky digestive problem ASAP.


By JoAnna Pendergrass, DVM 

March 21, 2022


Our dogs love us unconditionally. And while we love them right back, it can be tough to deal with a pooch whose digestive system is on the fritz.


Gastroenteritis in dogs is a common condition that is challenging to manage and can make dogs feel icky. If left untreated, gastroenteritis can progress to a life-threatening condition called Acute Hemorrhagic Diarrhea Syndrome (AHDS), formerly known as hemorrhagic gastroenteritis.

There's a lot to talk about with gastroenteritis, so let's dive right in so that you can learn all you need to know to make your pup's tummy feel better.

What is Gastroenteritis?

Gastroenteritis is inflammation of the stomach and intestines. It is categorized as either acute or chronic. Acute gastroenteritis occurs suddenly, while chronic gastroenteritis can take weeks or even months to develop.

Symptoms of Gastroenteritis in Dogs

Gastroenteritis in dogs has many symptoms, but diarrhea is the main one. We'll focus on that first.

When dogs have gastroenteritis, their poop will change in consistency over time. The poop will be soft and wet initially, then become increasingly watery, possibly with mucus. Dogs may also strain to poop and have bathroom accidents in the house.

The diarrhea is often frequent, in large amounts, and may be explosive. Sometimes, the diarrhea will be bloody. Bloody diarrhea is a medical emergency that warrants an immediate trip to the emergency hospital.

Dogs with gastroenteritis may also vomit occasionally, especially after eating a meal. The vomit may be yellow from bile that is produced in the liver. As with diarrhea, bloody vomit is a medical emergency and requires immediate treatment.


Other symptoms of gastroenteritis in dogs are listed below:

  • Fever

  • Nausea

  • Listlessness

  • Lethargy

  • Appetite loss

  • Dehydration

  • Tender hind end

  • Tender abdomen, with reluctance to be touched or picked up by the belly

  • Weight loss (common with chronic gastroenteritis)


Dehydration is especially concerning in puppies and older dogs, who can become quickly dehydrated because of diarrhea-associated fluid loss.

Surprisingly, some dogs with gastroenteritis can appear just fine, aside from diarrhea. Don't be fooled, though. Gastroenteritis needs prompt diagnosis and treatment.

Because gastroenteritis can progress to AHDS, it's good to know the symptoms of AHDS:

  • Sudden onset of bloody, watery diarrhea

  • Bloody vomit

  • Lethargy


AHDS requires immediate emergency veterinary care.

What Causes Gastroenteritis in Dogs?

A dog's digestive system has a microbiome, a collection of all microorganisms in the gut which helps with digestion. Anything that disrupts the normal gut microbiome can cause gastroenteritis.

The list of causes of gastroenteritis is long:


It is not uncommon for the cause of a dog's gastroenteritis to remain unknown.

Diagnosing Gastroenteritis in Dogs

If your dog has symptoms of gastroenteritis, don't delay in making an appointment with your veterinarian. And remember—if your dog has bloody diarrhea or vomit, take them to the emergency veterinary clinic right away.

Gastroenteritis is a diagnosis of exclusion, meaning that other diseases that could be causing your dog's symptoms need to be ruled out first. Excluding other diseases takes a lot of detective work by you and your vet.

With so many potential causes of gastroenteritis, your veterinarian will ask you numerous questions, such as those listed below:

  • What has your dog eaten in the past 48 hours?

  • Has your dog eaten anything unusual or spoiled recently?

  • When did the diarrhea start, and what has it looked like? Is your dog also vomiting?

  • Does your dog have chronic illnesses, such as diabetes?


Your veterinarian will also examine your dog from head to toe, paying close attention to your pup's abdomen and checking for signs of dehydration.

Next, your veterinarian will run several diagnostic tests to get a better idea of what's going on. These may include:

  • Blood work

  • Urinalysis

  • Fecal exam (to check for intestinal parasites)

  • Abdominal X-ray

  • Abdominal ultrasound


Treatment for Gastroenteritis in Dogs


The main treatment goals for gastroenteritis are to stop the diarrhea and vomiting, restore hydration, and restore the proper balance of electrolytes (e.g., sodium, potassium). Various medications are available to address these treatment goals:

  • Antibiotics, such as metronidazole

  • Anti-nausea and vomiting medications

  • Anti-diarrheal medications

  • Medications to prevent stomach ulcers

  • Probiotics to restore your dog's healthy gut microbiome


Gastroenteritis can be treated at home. However, severe cases of gastroenteritis require in-hospital treatment, including intravenous fluid therapy.

Proper nutrition is critical when treating gastroenteritis in dogs. Your veterinarian will likely recommend withholding food from your dog for up to 48 hours to rest his digestive system. If your dog is no longer vomiting, you can then start feeding him a bland diet in small, frequent amounts. A bland diet for dogs with gastroenteritis includes food like unseasoned, boiled chicken.

Rehydration options include adding an electrolyte supplement to your dog's water or giving your dog Gatorade or Pedialyte. Your veterinarian can recommend which rehydration option would be best for your dog.


Regarding recovery time, acute gastroenteritis often resolves quickly, but chronic gastroenteritis takes longer to treat.


Treatment for AHDS is aggressive. Unfortunately, AHDS is so severe that dogs can still succumb to the disease despite the aggressive treatment.

Gastroenteritis is a common disease in dogs that can be challenging to diagnose and treat. If your dog is showing any signs of gastroenteritis, make an appointment with your veterinarian so that your dog's tummy health can get back on track as soon as possible.

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