Gastroenteritis in Cats

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

What are the clinical signs of gastroenteritis?

Most cats with gastroenteritis will have intermittent episodes of vomiting and diarrhea. The vomit may contain foamy, yellowish bile, especially after emptying the stomach. Many owners observe dry heaving or gagging after their cat 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.

"Most cats with gastroenteritis will have intermittent episodes of vomiting and diarrhea."

Many cats will exhibit tenderness when picked up around the abdomen or resist handling the stomach and hindquarters. Most cats affected with gastroenteritis will appear less active (lethargic), have a decreased appetite, and may hide. A low-grade fever is also 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, meaning your veterinarian needs to eliminate or rule out other possible causes. A good medical history is the first step toward finding the cause of the vomiting, diarrhea, and lethargy. Some critical information in your cat’s medical history includes:

• 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
• Recent exposure to a new animal or person
• Previous episodes of vomiting and diarrhea (including their cause and treatment)
• Any illness within the past month
• Any chronic illnesses that your cat may have
• Any medications, vitamins, or supplements given within the past month

Your veterinary health team may have you complete a questionnaire before your visit. See the “Diarrhea Questionnaire and Checklist for Cats” handout for an example.

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

At this stage, your veterinarian may recommend diagnostic testing, including: 

• Complete blood cell count (CBC) - indicates the presence of dehydration, anemia, and infection
• Serum chemistries and electrolytes - detect organ system abnormalities and electrolyte imbalances caused by vomiting and diarrhea
• Fecal test - detects intestinal parasites (e.g., roundworm, hookworm, giardia)
• Urinalysis - detects urinary tract infections, kidney disease, dehydration, and diabetes
• Abdominal radiographs (X-rays) - search for stomach or intestinal obstruction and other abnormalities
• Abdominal ultrasound - searches for intestinal obstructions, certain cancers, or other abnormalities

The severity and duration of your cat’s symptoms, his 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:

• Infections (bacterial, viral, fungal, or parasitic)
• Foreign bodies (especially string or thread) or other objects
• Intussusception (the telescoping of the intestine into itself, causing an intestinal blockage)
• Tumors/cancers
• Poisoning/toxins (e.g., plants, cleaning agents)
• Endocrine diseases (e.g., diabetes, hyperthyroidism)
• Pancreatic, liver, or kidney disease

This is only a partial list of more serious conditions that can cause vomiting and diarrhea in cats. Your veterinarian may discuss other possibilities based on your cat’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 restoring blood electrolyte balance (sodium, potassium, and chloride). Depending on your cat’s degree of dehydration, this fluid replacement may be given orally, subcutaneously (under the skin), or by intravenous (IV) treatment.

"The principal treatment of gastroenteritis consists of rehydration and restoring blood electrolyte balance..."

Medical treatment may also include:

• Antibiotics (e.g., metronidazole, ampicillin) may be administered if the clinical signs are severe or if diagnostic tests suggest a bacterial infection.
• Anti-emetic or anti-vomiting medications, such as maropitant (Cerenia®) or metoclopramide (Reglan®), may be given to your cat.
• Gastrointestinal protectants, such as famotidine (Pepcid®) or ranitidine (Zantac®), may be used to prevent stomach ulcers.

Food may be withheld for 8-12 hours during the initial stages of treatment and then slowly be reintroduced in small, frequent feedings of a highly digestible, low-fat, and low-fiber diet. Your veterinarian will advise you on the best diet to feed your cat for a speedy recovery.

What is the prognosis for gastroenteritis?

Most cases of acute gastroenteritis improve rapidly after rehydration. Call your veterinarian if the vomiting and diarrhea do not improve significantly within 24-48 hours of treatment. Gastroenteritis is common in cats. Early recognition and treatment are the cornerstones to returning your cat to a normal healthy state as quickly as possible.