ASPCA logo Diarrhea is characterized by frequent loose or liquid bowel movements. It can be caused by something as simple as a change in diet or a more serious illness or infection. Diarrhea may be sudden in onset and short in duration. It can also last for weeks to months or occur off and on. A single bout of diarrhea is generally not a cause for concern in cats-but if it persists for more than a day or two, it can lead to dehydration.

What Causes Diarrhea?

Change in diet
Dairy or other food intolerance
Ingestion of spoiled food
Hairballs
Allergic reaction
Bacterial or viral infection
Internal parasites, such as roundworms, coccidia and Giardia
Inflammatory bowel disease
Kidney or liver disease
Cancer or other tumors of the digestive tract
Certain medications
Hyperthyroidism
Colitis

What Are the General Symptoms of Diarrhea?

Loose, frequent stools are the most common symptoms of diarrhea. Other signs include flatulence, the passage of blood in mucus or stool and straining to defecate. Lethargy, dehydration, fever, vomiting, decreased appetite, weight loss and an increased urgency to defecate may also accompany diarrhea.

If your cat’s diarrhea is accompanied by bloody or black stools, he could be experiencing internal bleeding of the stomach or small intestine and should be examined by a vet immediately.

How Do I Treat Diarrhea?

It is often recommended that you avoid giving your pet any food for 12-24 hours while he’s experiencing diarrhea, but do provide plenty of fresh, clean water to stave off dehydration. Check with your veterinarian about the proper course of treatment for your cat’s specific case.

When Should I Take My Cat to the Vet?

Bring your cat to the vet if his diarrhea continues for more than a day, or if you observe lethargy, vomiting, fever, dark-colored or bloody stools , straining to defecate, decreased appetite or unexplained weight loss.

What Can I Expect at the Vet's Office?

Your veterinarian will examine your pet for underlying illnesses, and may take a stool sample to check for the presence of internal parasites, as well as conduct blood work to identify a possible cause of the diarrhea.

Other diagnostic tests might include radiographs, ultrasound, cultures, endoscopy and biopsy. The diagnostic tests performed and treatment recommended will depend on how the long the diarrhea has been present and the severity of your pet’s condition.

Are Certain Cats Prone to Diarrhea?

Long-haired cats who have frequent hairballs may experience periodic bouts of diarrhea. Furthermore, cats who spend a lot of time outdoors may be at an increased risk for internal parasites or ingestion of inappropriate food, which could lead to diarrhea.

How Can I Prevent Diarrhea?

Try to avoid giving your cat dairy foods, no matter how much he likes them! Almost all cats enjoy the taste of milk or yogurt, but some adult cats do not have a sufficient amount of lactase, the enzyme necessary for the digestion of diary products. Undigested lactose moves to the large intestine, where it ferments-and can cause a cat to have gas or diarrhea.

Also, if you decide to switch your cat’s food, it’s a good idea to introduce it gradually, mixing it with the old brand to insure an easier transition for your pet’s GI tract.

WebMD Veterinary Reference from the ASPCA