Why Does My Cat Have Diarrhea? Diarrhea (Sudden) in Cats

Cecilia de Cardenas
Apr 30, 2009
Image: Photo Grapher / via Image Bank

Acute Diarrhea in Cats

Acute diarrhea has four general reasons for occurring: osmotic imbalances, over secretion, intestinal exudation or motility disorders. Osmotic imbalances occur when the concentration of food molecules in the intestine is too high. Water is drawn into the intestine by the excess molecules, causing diarrhea. Over secretion occurs when the intestine secretes too much fluid after being exposed to bacteria or toxins. Intestinal exudation describes a slow oozing of blood fluids through ulcers or other breaks in the intestine’s tissue layers. This exudation can be mild or very severe.

Motility disorders refer to how active the intestine is and its capability of moving contents through. An intestine that is under functioning in its ability to muscularly contract and push the contents out of the canal is most common; this condition is referred to as ileus. Conversely, motility can be increased as well, so that the intestine contracts too quickly and fluid which normally is absorbed is lost into the feces. Sometimes diarrhea can be from a combination of these causes. Intestinal infections can also cause the intestine to over secrete. They also tend to change the motility of the intestine.

Symptoms and Types of Diarrhea in Cats

  • More water in feces than normal
  • May have an increased volume of feces
  • Fecal accidents
  • Vomiting
  • Blood or mucus in the feces
  • Straining to defecate
  • Possible listlessness
  • Possible anorexia
  • Depression
  • Abdominal pain
  • Fever
  • Weakness

Why Does My Cat Have Diarrhea?

  • Systemic illness
  • Eating garbage, nonfood material or spoiled food
  • Changes in diet
  • Hypersensitive digestive tract
  • Addison’s disease - less active than normal adrenal glands
  • Liver disease
  • Kidney disease
  • Pancreatic disease
  • Ingesting foreign bodies
  • Intestinal blockage
  • Infection
  • Viral
  • Bacterial
  • Parasitic
  • Rickettsial – bacterial infection typically acquired through parasites such as fleas, ticks, etc.
  • Fungal
  • Drugs and Toxins


Your veterinarian will perform a complete physical exam on your cat. You will need to give a thorough history of your cat’s health, including a background history of symptoms, and possible incidents that might have precipitated this condition. A blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis will be performed so as to rule out other causes of disease. X-rays can help to rule out the possibility that your cat swallowed inappropriate items, which may be blocking or irritating the intestine.

Blood tests can be performed to rule out an inflamed pancreas, or a pancreas that is not producing enough digestive enzymes. Blood tests can also be used to check levels of cobalamin and folate (vitamins) as these are normally absorbed in the intestine.

Laboratory tests can be performed on fecal samples to check for Giardia and Cryptococcus infections. A smear of feces should be checked for parasite eggs as well. Your veterinarian may perform an endoscopy to take a sample of your cat’s intestine for histopathologic examination at the laboratory.

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