Acute Gastroenteritis in Dogs: Explained by Our Vets

Acute Gastroenteritis in Dogs: Explained by Our Vets

Published Date

Published Date

July 29, 2025

July 29, 2025

Last Updated

Last Updated

September 22, 2025

September 22, 2025

A veterinarian is giving a dog a checkup for signs of acute gastroenteritis. Another vet is assisting.
A veterinarian is giving a dog a checkup for signs of acute gastroenteritis. Another vet is assisting.
A veterinarian is giving a dog a checkup for signs of acute gastroenteritis. Another vet is assisting.

Your dog’s health can deteriorate quickly, even without the earliest signs to warn you. When this happens, we often wonder if we could’ve done something to catch up on it. But in many cases, these conditions are difficult to predict, expect, and prepare for. 

One of these is acute gastroenteritis in dogs, the sudden inflammation of the stomach and intestines. This condition is characterized by sudden diarrhea and vomiting. While most cases are mild and short-lived, others can progress into more dangerous conditions.

Acute Hemorrhagic Gastroenteritis (AHGE) and Acute Hemorrhagic Diarrhea Syndrome (AHDS), two different names for a serious condition that requires emergency care. While AHDS can be messy, most dogs can make full recoveries.

With that, let’s talk more about acute gastroenteritis in dogs.

What Causes Acute Gastroenteritis in Dogs?

The most common causes of acute gastroenteritis in dogs stem from anything that irritates the lining of your dog’s stomach and intestines. This can be anything from simple food to some serious infections. 

Dietary Indiscretion

One of the leading reasons for acute gastroenteritis in dogs is when they eat something they shouldn’t. While it's adorable that they’re naturally curious, it can be dangerous when they eat dangerous items such as spoiled food, trash scraps, and sharp objects. 

When they do, the foreign objects overwhelm the digestive system, triggering inflammation in the stomach and intestines. This often results in abrupt digestive symptoms, with vomiting as a common one. 

Changes and Issues With Food

Changing your dog’s food too quickly can also be the source of this digestive problem. From switching brands, types of food, or even the amount, even the smallest changes can potentially trigger gastrointestinal upset. 

Additionally, any food allergies or intolerances can also cause acute gastroenteritis in dogs. Some dogs may have them, and some may not. Those who do have them can have reactions to common food allergens such as beef, chicken, dairy, wheat, or artificial additives. 

This occurs when the food they eat causes an inflammatory response that irritates the lining of the stomach and gut.

Infections

Certain viruses and bacteria are also known to cause inflammation, notably:

  • Canine Parvovirus. CPV works by attacking the lining of the stomach and intestines, especially in puppies. As a result, affected dogs will experience impaired nutrient absorption and intestinal damage. 

  • Canine Distemper Virus. CDV works a little differently. While it does attack the lining of the gastrointestinal system, it also suppresses the immune system of dogs. This makes them vulnerable to secondary infections. 

  • Salmonella. Salmonella spreads through the ingestion of contaminated food, water, and feces. The bacteria release toxins in the stomach and intestines, which damage their lining. 

  • Escherichia coli. E. coli also spreads through the ingestion of contaminated material, as well as direct contact with it. Some strains can attach to the intestinal lining. 

Parasites

On the other hand, intestinal parasites can also cause acute gastroenteritis in dogs and chronic gastrointestinal problems. They work by attaching to the intestinal wall and absorbing the nutrients meant for the dogs themselves. Common examples include Giardia, hookworms, and coccidia.

Medications and Toxins

Dogs that ingest human medications, toxic substances, and chemicals can also experience acute gastroenteritis. Common examples include cleaning products, prescription medicines, and pesticides. 

Even human foods and ingredients such as grapes and xylitol can cause irritation within the gastrointestinal tract. Canine medication used improperly can also be the reason. 

Stress

Your dog’s emotions can also have direct physical effects on the digestive tract. Dogs that get anxious during travel, car rides, loud noises, or vet visits can develop stress-induced acute gastroenteritis. 

This happens because the gut and brain are interconnected by the gut-brain axis. When a dog gets stressed, it triggers a release of hormones that disrupt the function of the digestive system. 

Other Health Issues

Other health conditions, such as tumors and kidney disease, can also be the cause of acute gastroenteritis in dogs. Kidney disease can result in a buildup of toxins, leading to gastrointestinal irritation.

Dogs at Risk of Acute Gastroenteritis

While this disease can affect any type of dog, some factors can increase the risk. This includes genetics, age, and history of GI problems. 

Acute gastroenteritis is common in small and toy dog breeds compared to larger ones. This is because they generally have shorter and smaller digestive systems, while some have sensitive ones. Because of their small size, they are also prone to dietary indiscretion.

Age is also a factor. Due to their young age, most puppies will still be unvaccinated, and some are just in the midst of completing their schedules. Because of this, they can be more prone to infections. This age group also tends to be more curious, being susceptible to dietary indiscretion.

Also, dogs with a history of other related gastrointestinal issues are more likely to experience acute gastroenteritis.

What Are the Symptoms of Acute Gastroenteritis in Dogs?

A veterinarian is checking a brown dog's condition and any sign of acute gastroenteritis.

If your dog shows any of the signs, it can be difficult to be sure. The condition presents similar symptoms to other milder diseases, so a keen eye is recommended. Here are the common signs of acute gastroenteritis in dogs:

  • Vomiting. Vomiting is often the first visible sign of trouble. The vomit may have food, bile, clear fluid, or foam, all of which signal stomach irritation. 

  • Diarrhea. The stool in affected dogs will appear watery or loose. Your dog may also have more frequent episodes of pooping. 

  • Lethargy and Weakness. You may see your dog wanting to rest and sleep more often, rather than play like its normal routine.

  • Loss of Appetite. Because of the constant discomfort and pain they feel, some dogs will lose interest in their favorite foods and treats. 

  • Abdominal Pain. Dogs with acute gastroenteritis can also feel a lot of pain in their belly.

Severe symptoms, often signaling Acute Hemorrhagic Diarrhea Syndrome, include:

  • Bloody Diarrhea. In severe cases, dogs will have bloody diarrhea. The blood is an indicator of the inflammation in the intestinal lining. 

  • Dehydration. As a result of vomiting, dehydration is to be expected. This can be seen as dry gums, sunken eyes, and reduced skin elasticity. 

  • Rapid Heart Rate. An increased heart rate can be a possible symptom as the heart works harder to improve circulation. 

  • Restlessness or Pacing. Affected dogs may appear unsteady and agitated. They may constantly move around the house.

How Painful Is Acute Gastroenteritis in Dogs?

Since acute gastroenteritis brings sudden symptoms to dogs, it can also be severe. This means a lot of pain and discomfort. In some cases, the symptoms can be mild, but in others, it’s full of persistent vomiting, bloody diarrhea, and severe pain.

How Do Vets Diagnose Acute Gastroenteritis in Dogs?

We use a combination of tests to determine your dog’s condition and accurately determine the cause. First, we will do an assessment of your dog and its medical history. We’ll ask you questions about the symptoms you observed at home. 

Next, we’ll proceed to laboratory tests. This includes: 

  • Bloodwork. A packed cell volume test measures the proportion of red blood cells in the blood. When a dog is experiencing acute gastroenteritis, the PCV will be above the 57% mark. 

  • Fecal Tests. A fecal exam, such as a fecal flotation test and fecal smear, will be done to identify any parasites or infections present. 

  • Imaging. Additional X-rays and ultrasounds can help us check your dog’s intestines and gut. We'll mostly be looking for obstructions, tumors, and foreign bodies.

Treatment for Acute Gastroenteritis in Dogs

Two veterinarians are keeping a dog still before giving medications for acute gastroenteritis. The pet owner is nearby.

Treatment needs to be given quickly to avoid any complications.

  • Fluid Therapy. Dogs with symptoms like vomiting and diarrhea can lead to significant dehydration. Replacing these lost fluids with fluid therapy can restore hydration levels. 

  • Medications. Specific medications for pain relief, anti-nausea, and stomach protectants will be prescribed from our pet pharmacy. If there's a secondary infection, we'll also provide antibiotics.

  • Bland Diet. Easily digestible food like boiled chicken and rice will help the digestive system recover. What's great about this is it's low in fat and gentle on the stomach.

  • Probiotics. We can also recommend probiotics for your dog because they can help promote gut health and improve the gut microbiome. This in itself can help prevent digestive upsets.

For severe cases of acute gastroenteritis, such as AHDS, our vets will focus on a more aggressive treatment style. We'll provide IV fluids for dehydration, to prevent the rapid loss of fluid, and to flush out potential toxins. 

In severe cases where protein levels are dangerously low, synthetic colloids or plasma transfusions will be given. These help restore protein levels, blood volume, and blood pressure. 

How Long Does Acute Gastroenteritis Last in Dogs?

With proper and timely care, acute gastroenteritis in dogs resolves within a few days. Most dogs make a full recovery, and the condition has an excellent prognosis if treated early. Hospitalization will be the most likely outcome to provide continuous support and monitoring.

It will take about 24 to 48 hours for mild cases to resolve. Cases caused by infections will need about 7 to 10 days, usually comprising the entire medication schedule. Acute gastroenteritis in dogs caused by parasites will take a few weeks to months for full recovery. 

However, if treatment is not given, AHDS can progress rapidly and become life-threatening.

How to Prevent Acute Gastroenteritis in Dogs?

While the condition can’t be fully prevented, there are some ways to protect your dog and reduce the risk.

  1. Keep Trash Away

Dogs love to scavenge, so make sure to keep trash, spoiled food, and other dangerous objects away from their reach. If possible, place them in solid containers to lock them away from your dog.

  1. Stick to a Consistent Diet

Dogs with sensitive stomachs do better on a steady, high-quality diet. It also helps to maintain the same brand and food type in their case. When transitioning to new diets, be sure to do it slowly. 

  1. Keep Up With Parasite Prevention

Internal parasites can silently damage your dog’s gastrointestinal tract, causing inflammation and infection. Make sure to have regular parasite preventives

“A healthy gut is the foundation of a healthy dog.”

- Dr. Rokas Proscevicius

Final Thoughts

Acute gastroenteritis in dogs can be alarming, but it’s completely treatable. The key is to get immediate help once you notice the signs. The best you can do is to protect your dog from this disease by making some changes around the house, your dog’s diet, and its health.

Frequently Asked Questions

Is acute gastroenteritis contagious in dogs?

Yes, acute gastroenteritis can be contagious in dogs when it’s caused by bacteria, viruses, and parasites. They can sometimes spread through the fecal-oral route, contaminated surfaces, or direct contact.

Is acute gastroenteritis contagious in dogs?

Yes, acute gastroenteritis can be contagious in dogs when it’s caused by bacteria, viruses, and parasites. They can sometimes spread through the fecal-oral route, contaminated surfaces, or direct contact.

Is acute gastroenteritis contagious in dogs?

Yes, acute gastroenteritis can be contagious in dogs when it’s caused by bacteria, viruses, and parasites. They can sometimes spread through the fecal-oral route, contaminated surfaces, or direct contact.

Is gastroenteritis in dogs an emergency?

Yes, it’s considered an emergency, especially if it's acute gastroenteritis in dogs. The condition can result in severe dehydration, blood in vomit or stools, and a rapid onset of its symptoms. The best way to help dogs recover is to provide emergency care.

Is gastroenteritis in dogs an emergency?

Yes, it’s considered an emergency, especially if it's acute gastroenteritis in dogs. The condition can result in severe dehydration, blood in vomit or stools, and a rapid onset of its symptoms. The best way to help dogs recover is to provide emergency care.

Is gastroenteritis in dogs an emergency?

Yes, it’s considered an emergency, especially if it's acute gastroenteritis in dogs. The condition can result in severe dehydration, blood in vomit or stools, and a rapid onset of its symptoms. The best way to help dogs recover is to provide emergency care.

Can I treat dog gastroenteritis at home?

Many cases of acute gastroenteritis in dogs can be treated at home. Start by withholding food for about 12 to 24 hours and providing lots of drinking water. After fasting, give your dog a bland diet, probiotics, and some fiber. If it still worsens, contact the vets.

Can I treat dog gastroenteritis at home?

Many cases of acute gastroenteritis in dogs can be treated at home. Start by withholding food for about 12 to 24 hours and providing lots of drinking water. After fasting, give your dog a bland diet, probiotics, and some fiber. If it still worsens, contact the vets.

Can I treat dog gastroenteritis at home?

Many cases of acute gastroenteritis in dogs can be treated at home. Start by withholding food for about 12 to 24 hours and providing lots of drinking water. After fasting, give your dog a bland diet, probiotics, and some fiber. If it still worsens, contact the vets.

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