Gastroenteritis in Dogs

Gastrointestinal distress is the most common reason dogs are seen at veterinary emergency facilities. This condition is characterized by vomiting and diarrhea and, since the potential causes of these two unpleasant conditions are immense, it’s a veterinarian’s job to narrow down the most plausible reasons. Since this is a disease of exclusion, there is not one specific test for diagnosis. Ruling out other causes is the best way to pinpoint gastroenteritis.

Common Causes of Gastroenteritis

Some common causes of vomiting and diarrhea are:

• Dietary indiscretion
  • Foreign material ingestion, such as toys, fabric, clothing, hair ties, baby pacifiers, and feminine products
  • Human food/table scraps
  • Sudden, non-acclimated diet change, like switching from one type of food to another with no gradual introduction phase
  • Toxin ingestion of items like medications, toxic plants, toxic human food, or chemicals
  • Ingestion of another pet’s food, such as an older pet eating high-fat/calorie puppy food
• Metabolic causes
  • Liver failure
  • Kidney failure
  • Neoplasia
  • Low red blood cell count
• Inflammatory bowel disease
• Infection or virus, like parvovirus in puppies
• Gastrointestinal parasites
• Foodborne illnesses, such as salmonella poisoning from raw food diets
• Food allergies
• Stress/anxiety
• Allergic/anaphylactic reaction
• Reactions to prescribed medications

Diagnostic Testing

Determining which of these causes is most probable for each pet is based on a thorough medical history, physical exam, and further diagnostics.

Possible questions that your veterinarian may ask to get a better medical history include:

• Have there been any recent diet changes?
• Is your dog known to chew on or get into things around the house?
• Do you know of anything abnormal that they may have eaten?
• Have they ever eaten something out of the ordinary in the past and needed to have medical care or surgery?
• Does your pet have any underlying medical problems?
• When did your primary veterinarian last perform blood work? Was it normal?
• Is your pet losing weight?
• How long have clinical signs been present?
• Has your pet been fully vaccinated?
• What is your pet’s current diet (raw food, kibble, canned food, or human food)?

Imaging and Other Diagnostic Tests

Based on the severity of clinical signs and physical exam findings, additional diagnostics may be recommended. These may include blood work to rule out metabolic causes, which checks the liver, kidney, electrolytes, and hydration. Radiographs or an abdominal ultrasound can also be used to look for an obstruction. If a dog eats foreign material, it can create an obstruction, which prevents gastric and intestinal contents from moving through the intestinal tract. This ultimately leads to accumulation in the stomach and intestines in front of the obstruction.

An obstruction can be seen through imaging like an ultrasound or radiograph. Imaging can also pick up masses or tumors that are cancerous and causing clinical signs. If infections like parvovirus are suspected, especially in young dogs, testing should be performed. A fecal sample will be sent away for analysis to look for gastrointestinal parasites.

Unfortunately, there is no universal blood panel or toxin panel that looks for all ingestible toxins. There are controlled (recreational) drug panels that can find illicit drug exposure based on a urine sample. If clinical signs and history indicate illicit drugs, then this panel may be recommended.

Out-Patient Therapy and Treatment

For dogs that have mild gastrointestinal clinical signs, meaning vomiting and/or diarrhea lasting under 24 hours, no blood in vomit or diarrhea, minimal appreciable dehydration, and relatively good health otherwise, supportive out-patient therapy may be recommended.

This commonly includes:

• Subcutaneous fluids administered under the skin to help hydrate over the following 8 – 12 hours
• Single injection of anti-nausea medication, like maropitant (Cerenia®), which lasts in the system for about 24 hours
• Antibiotics or probiotics for management of diarrhea based on clinical picture and physician preference
• Bland diet instructions

For dogs that have more profound clinical signs, including those with clinical signs present for over 24 hours, dehydration noted on exam, bloody vomit and/or diarrhea, pain and/or clinically sick, in-patient therapy may be recommended.

This commonly includes:

• Admission to the hospital
• IV catheter placement
• IV fluids to help rehydrate and correct electrolyte abnormalities
• Administration of anti-nausea medications
• Serially reassessment of vitals and clinical signs to monitor improvement and note any declines
• Rechecking radiography or ultrasound if initially abnormal

In general, gastroenteritis will improve quickly with treatment with no long-term implications. Gastroenteritis can reoccur again if the animal is exposed to similar circumstances or has a different gastrointestinal insult.

Hemorrhagic Gastroenteritis

There is a subset disease of gastroenteritis that is much more severe and can be life threatening. Hemorrhagic gastroenteritis (commonly called HGE) is an acute onset of severe bloody vomiting and diarrhea. This is more commonly noted in small-breed dogs like Yorkshire Terriers, Miniature Schnauzers, Miniature Poodles, and Maltese. The exact causes of HGE are unknown, but thought to be secondary to an infection or hypersensitivity to Clostridium perfringens.

Clinical signs include:

• Severe vomiting that may be bloody
• Severe diarrhea that is bloody
• Lethargy
• Collapse
• Dehydration
• Shock
• Low blood pressure and/or temperature

Diagnosis is based on clinical signs, diagnostics, and response to therapy. HGE is characterized by elevated red blood cell count (hemoconcentration) over 60% (normal levels are 25 – 55%). Other changes in blood work can include a low protein level, due to losses in the GI tract. Dogs with severe signs can have hypoglycemia (low blood glucose), electrolyte abnormalities, and coagulation (blood clotting problems) due to the large amount of fluid lost into the intestinal tract.

In dogs that have suspected HGE, quick, aggressive treatment is recommended. This includes IV catheter placement, IV fluids, anti-nausea medication, antibiotics, and gastroprotectants. In some cases where dogs lose a large amount of fluid from vomiting and diarrhea, they may also need blood or plasma transfusions. Most cases of HGE respond well to treatment and make a full recovery in 24 – 48 hours. HGE can be fatal in dogs with delayed treatment, small-breed dogs, or those with secondary, underlying health conditions.

Any dog with suspected HGE should be evaluated immediately by a veterinary hospital, as earlier treatment is recommended.