Gastroenteritis in Cats

What is gastroenteritis?

Gastroenteritis refers to inflammation of the gastrointestinal tract, meaning the stomach and the intestines. It can be caused by infection with bacteria, viruses, or parasites; reactions to medications; or even new foods. The condition often causes abdominal discomfort, pain, diarrhea, vomiting, and/or other clinical signs (symptoms).

What are the symptoms of gastroenteritis?

Gastroenteritis is most often characterized by vomiting and diarrhea.


Most cats with gastroenteritis will have intermittent episodes of vomiting and diarrhea. The vomit may contain foamy, yellowish bile, especially after the stomach has been emptied. Many owners will observe “dry heaving” or gagging after their pet eats or drinks. Large volumes of diarrhea will usually be produced several times a day. The diarrhea may have the consistency of soft-serve ice cream and is often pale in color. Many cats will exhibit tenderness when picked up around the abdomen or will resist handling of the stomach and hindquarters. Most cats affected with gastroenteritis will appear less active (lethargic) and will have a decreased appetite. A low-grade fever is common. Dehydration can occur quickly if the vomiting and diarrhea persist for more than 24 hours.

How is gastroenteritis diagnosed?

Gastroenteritis is a diagnosis of exclusion, which means that your veterinarian needs to eliminate or “rule out” other possible causes. The first step toward finding the cause of the vomiting, diarrhea, and lethargy is a good medical history.

Your veterinarian will need to know:

  • Your cat’s current diet, how often you feed your cat, and how much he or she eats
  • Everything your cat ate or drank within the past 48 hours
  • Any new foods, treats, or rewards
  • Recent exposure to pesticides, medications, cleaning agents, or similar materials in your home environment
  • Recent exposure to a new animal or person
  • Previous episodes of vomiting and diarrhea (including their cause and treatment)
  • Recent illness (within the past month)
  • Any chronic illnesses
  • Any medications or supplements given within the past month

After obtaining the medical history, your veterinarian will perform a thorough physical examination. He or she will look for evidence of dehydration, abdominal pain or tenderness, bloating or gas, swellings, and any other physical abnormality. Your cat’s temperature and other vital signs will also be checked.

At this stage, your veterinarian may recommend diagnostic testing, which could include:

  • A complete blood cell count (CBC), which can indicate the presence of dehydration and infection
  • Serum chemistries and electrolytes, which detect organ system abnormalities and electrolyte imbalances caused by the vomiting and diarrhea
  • A urinalysis, for detecting urinary tract infections, kidney disease, dehydration, and glycosuria (glucose in the urine), which may indicate diabetes
  • Abdominal radiographs (x-rays) to search for gastric (stomach) or intestinal obstruction and other abnormalities
  • An abdominal ultrasound to look for intestinal obstructions or other abnormalities

The severity and duration of your cat’s illness will determine which tests your veterinarian chooses to run.

The severity and duration of your cat’s symptoms, his or her medical history, and the physical examination will determine which tests your veterinarian chooses to run.

What are some of the causes of gastroenteritis?

There are many causes of vomiting and diarrhea in cats. Some of the more common conditions that your veterinarian will attempt to rule out during the diagnostic workup include:

  • Systemic infections such as pneumonia, septicemia (a potentially life-threatening bacterial infection in the blood), urinary tract infection, and meningitis
  • Foreign bodies (especially string or thread) or other objects
  • Intussusception (the telescoping of the intestine into itself, causing an intestinal blockage)
  • Tumors
  • Poisoning
  • Exocrine pancreatic insufficiency (failure of the pancreas to make sufficient digestive enzymes)
  • Hypoadrenocorticism (Addison’s disease, the failure of the adrenal gland to make sufficient cortisol)
  • Hyperthyroidism (an overactive thyroid gland)

Your veterinarian may discuss other possibilities based on your pet’s specific condition or history.

How is gastroenteritis treated?


Once the results of the diagnostic tests are known and other causes of the clinical signs have been eliminated, your veterinarian will prescribe a treatment plan. The principal treatment of gastroenteritis consists of rehydration and the restoration of blood electrolyte balance (sodium, potassium, and/or chloride). Depending on the pet’s degree of dehydration, this fluid replacement may be given orally, subcutaneously (under the skin), or by intravenous (IV) treatment.

Antibiotics may be administered if the clinical signs are severe or if diagnostic tests suggest a bacterial infection. Antidiarrheal agents or drugs to alter intestinal motility (activity) may be used in certain conditions, and only after intestinal obstruction or other mechanical and anatomical issues have been ruled out.

Food—and sometimes water—is often withheld during the initial stages of treatment and then slowly reintroduced via small, frequent feedings of a bland diet. Your veterinarian will advise you on the best diet to feed your pet for a speedy recovery.

What is the prognosis (expected outcome) for gastroenteritis?

Most cases of acute gastroenteritis improve rapidly after rehydration. If the vomiting and diarrhea do not improve significantly within 48 hours of treatment, call your veterinarian.

Early recognition and treatment are the cornerstones to rapidly returning your cat to his or her normal healthy state.

Gastroenteritis is common in cats. Early recognition and treatment are the cornerstones to returning your cat to his or her normal healthy state as quickly as possible.

This client information sheet is based on material written by: Ernest Ward, DVM

© Copyright 2012 Lifelearn Inc. Used and/or modified with permission under license.