Definition of Diarrhea

Diarrhea is defined as the rapid movement of fecal matter through the intestine, resulting in poor absorption of electrolytes, nutrients and water and leading to abnormally frequent and voluminous evacuation of loose, unformed, soft-to-fluid stool. Diarrhea can be acute (come on suddenly) or chronic (lasting more than a week or two). Diarrhea is a symptom, not a disease. It can be caused by any number of distinct medical conditions.

How Diarrhea Affects Cats

Regardless of the exact reason for a cat’s diarrheic condition, the effects of diarrhea are fairly consistent and include some combination of the following symptoms:

• Dehydration
• Depression
• Weakness
• Lethargy
• Loss of appetite (inappetence; anorexia)
• Weight loss (uncommon in cats)
• Poor hair coat
• Brick red gums and other mucous membranes
• Pale gums and other mucous membranes
• Bad breath (halitosis)
• Nausea
• Vomiting
• Arched back (due to abdominal pain)
• Straining to defecate (tenesmus; more common in dogs; in cats, assess ability to urinate)
• Foul-smelling, watery stool; may contain mucus or undigested fat (steatorrhea)
• Dark, tarry loose stool (small bowel in origin; contains digested blood [melena])
• Greasy, blood-streaked loose stool (large bowel in origin; contains fresh red blood [hematochezia])
• Flatulence (passing gas; “farting”)

Causes of Diarrhea in Cats

Diarrhea is typically caused by some infectious, chemical or physical irritation of the intestinal mucosa (the sensitive tissue lining the gastrointestinal tract). It takes roughly eight hours for food to pass through the small intestine and into the colon. The small intestine is responsible for absorbing approximately 80% of the fluid from ingested matter, while the large intestine (colon) further concentrates and forms the stool in preparation for defecation. When food passes too quickly through the system, it is incompletely digested, and the liquid component is not fully absorbed, resulting in diarrhea.

A number of things can cause intestinal irritation and the corresponding abnormally rapid transit of ingested material, including:

• Internal parasites (hookworms, tapeworms, roundworms, whipworms, others)
• Infectious microorganisms (bacteria, viruses, fungi, protozoa; often from recent travel, boarding, hospitalization, trips to the groomer, etc.)
• Spoiled, unfamiliar, indigestible or decaying food
• Rich, spicy, salty or greasy food
• Dead animals (usually rodent or bird carcasses)
• Raw meat, fish or poultry
• Indigestible foreign objects (sticks, stones, bones, pebbles, cloth, plastic, rug fragments, bottle caps, etc.)
• Toxic substances (antifreeze, gasoline, household cleaners, insecticides, rodent bait, toilet bowl inserts, certain wild and domestic plants, certain wild mushrooms, over-the-counter and prescription drugs)
• Allergies to or intolerance of certain foods (milk, meat, fish, poultry, corn, wheat, eggs, soy, others)
• Stress (visits to the veterinarian, travel, cat shows, introduction of new household pets, household relocation, unfamiliar visitors)
• Excitement
• Overeating
• Abrupt change in diet
• Unfamiliar water (standing water in puddles or ponds, unfamiliar tap water during travel; protozoal organisms such as Giardia thrive in contaminated water)
• Administration of antibiotics or other medications
• Heavy metals
• Intestinal foreign bodies (may or not cause a mechanical obstruction)
• Cancer (neoplasia; especially lymphosarcoma and adenocarcinoma in domestic cats; also mast cell tumors)
• Irritable bowel syndrome; inflammatory bowel disease
• Underlying systemic disease (feline leukemia virus [FeLV], feline immunodeficiency virus [FIV], feline infectious peritonitis [FIP], feline panleukopenia, liver [hepatic] disease, kidney [renal] disease, hypoadrenocorticism [Addison’s disease], pancreatitis, hyperthyroidism [common in cats], diabetes mellitus, exocrine pancreatic insufficiency [EPI; more so in dogs], lactase deficiency [intolerance to dairy products; especially prominent in cats], others)

Prevention of Diarrhea

The best way to prevent diarrhea is to avoid the things that cause it. Companion cats should be on a regular de-worming protocol as advised by their veterinarian. Food allergies can be identified by a medically-supervised elimination diet. Dietary changes should always be made gradually. Cats should eat a well-balanced commercial diet, which can include dry kibble, canned food or both. Most veterinarians discourage feeding a raw diet. Cats should be kept away from garbage, rat poison, standing pools of water, dead birds and rodents, chemicals, household cleaners, fertilizer, prescription drugs and other toxins and potentially dangerous foreign objects.

They also should be kept away from sick cats and be housed in a calm, stress-free environment. The litter box should be changed frequently. Food bowls should be washed with soap and hot water after each meal. Antibiotics should only be used when necessary, to promote a healthy gastrointestinal bacterial flora and to reduce the likelihood of antibiotic-resistant bacterial strains. Systemic illnesses should be diagnosed and treated (or at least managed) as effectively as possible. Water from home or bottled water should be used when traveling.

Special Notes

Cats kept in crowded or unsanitary environments are at an increased risk of developing diarrhea. Free-roaming outdoor cats and very young kittens are also predisposed.

Some of the microorganisms that cause diarrhea in cats have the potential to infect people, especially those whose immune systems are weakened or suppressed. These include: Salmonella (bacteria), enterotoxigenic Escherichia coli (bacteria), Campylobacter (bacteria), Giardia (protozoa), Toxocara (roundworms), Ancylostoma (hookworms), Echinococcus, Toxoplasma, Cryptosporidium (protozoa), Tritrichomonas (protozoa), Clostridium (bacteria) and Shegella (bacteria), among others. “Zoonosis” is the medical term for diseases of animals that may be transmissible to humans.

Causes