My cat has diarrhea — what should I do?

Diarrhea in cats ranges from mild and self-limiting to life-threatening. This guide explains causes, home care, when to seek urgent or emergency veterinary help, and kitten-specific concerns.

Overview

Diarrhea is a common symptom in cats and can be caused by something minor (a recent diet change) or something serious (infection, toxins, or systemic disease). This guide helps you assess severity, do safe at-home steps, recognize red flags, and decide whether to monitor, seek urgent care, or get emergency treatment.

Sources used for this article include the Merck Veterinary Manual and the Cornell University Feline Health Center (see citation section at the end).

Quick triage: When to See a Vet Immediately

Seek immediate veterinary care (emergency visit) if your cat has any of the following:

• Repeated vomiting and inability to keep water down
• Severe weakness, collapse, or unresponsiveness
• Signs of moderate to severe dehydration (see dehydration monitoring below)
• Bloody stool or large amounts of fresh blood
• Severe abdominal pain (vocalizing, hunched posture, guarding)
• Very young kittens, very old cats, or cats with serious chronic illnesses (e.g., diabetes, kidney disease)
• Suspected toxin ingestion or foreign-body obstruction

Litter-Box Assessment: What to Check

Before you leave home or call the vet, gather as much information as possible from the litter box and environment:

• Frequency: How often is your cat having diarrheal stools compared with normal?
• Volume: Is the stool more or less volume than usual?
• Consistency and color: Watery, muddy, yellow, green, black/tarry (melena), or bright red blood
• Mucus or pus: Mucus often points to colitis (large-bowel inflammation)
• Presence of worms or segments: Visible worms suggest parasitic infection
• Smell and odor: Extremely foul odor can indicate bacterial overgrowth/enteritis
• Behavior: Is the cat otherwise bright, eating and drinking, grooming normally, or lethargic and hiding?

Acute vs Chronic Diarrhea

• Acute diarrhea: sudden onset, usually less than 2 weeks. Often caused by diet change, parasites, stress, toxins, or acute infections.
• Chronic diarrhea: persistent or recurrent diarrhea lasting 3 weeks or longer. More likely due to inflammatory bowel disease (IBD), chronic infections, parasites that were missed, metabolic disease (hyperthyroidism, liver or kidney disease), exocrine pancreatic insufficiency (EPI), or intestinal cancer (e.g., lymphoma).

Differential Diagnosis (Common causes, ranked roughly by likelihood)

Your veterinarian will use the history, physical exam, stool testing, bloodwork, imaging, and possibly biopsy to narrow this list.

Home Care — What You Can Safely Do

Note: Do not attempt to treat suspected serious conditions at home. If your cat is severely ill or you suspect toxins, go to a vet immediately.

For mildly affected adult cats that remain bright, alert, eating and drinking:

• Keep fresh water available at all times. Encourage drinking; dehydration is a common complication.
• Offer small, frequent meals rather than a long fast. Cats are obligate carnivores and are at risk of hepatic lipidosis if they stop eating for more than 24–48 hours. A bland, easily digestible diet (small amounts of plain cooked chicken or a veterinary gastrointestinal diet like Hill’s i/d or Royal Canin Gastrointestinal) is appropriate after 12–24 hours of mild illness.
• Avoid giving over-the-counter anti-diarrheal drugs (loperamide, bismuth subsalicylate) or antibiotics unless directed by your veterinarian — many human medications are unsafe for cats.
• Probiotics formulated for pets (recommended by your veterinarian) may help some cases; discuss products and dosing with your vet first.
• Collect a fresh stool sample and note timing and behavior changes to tell your vet.
• Keep the cat’s environment stress-free: minimize changes, provide hiding places, and keep the litter box clean and accessible.

Dehydration: How to Monitor at Home

Diarrhea can quickly cause dehydration, especially in kittens. Signs to watch for:

• Decreased skin elasticity (skin tenting when gently lifted)
• Dry or tacky gums
• Reduced tearing or droopy eyes
• Sunken eyes
• Lethargy or weakness
• Decreased urine production or dark concentrated urine

Do not attempt to force fluids into a dehydrated cat at home without instruction — unsafe techniques can lead to aspiration or injury. Your vet may provide subcutaneous or intravenous fluids as needed.

Diagnostic Approach Your Vet May Use

• Physical exam and history review
• Fecal flotation and direct fecal smear for parasites
• Giardia or PCR testing of stool
• Fecal culture for bacterial pathogens if indicated
• Complete blood count, chemistry panel, and T4 (thyroid) in older cats
• Abdominal ultrasound or x-rays if obstruction, mass, or chronic disease suspected
• Biopsy (endoscopic or surgical) when IBD or lymphoma is suspected

Kitten-Specific Concerns

Kittens dehydrate and deteriorate much faster than adults. Common kitten issues include parasitic infections, panleukopenia (severe and potentially fatal), and failure of passive transfer of immunity.

Take kittens to a veterinarian urgently if they have any of the following:

• Diarrhea with weakness, low body temperature, or poor nursing
• Bloody diarrhea
• Vomiting or inability to keep fluids down
• Signs of hypoglycemia (tremors, weakness, collapse)

Treatment Overview (What to Expect at the Vet)

Treatment depends on the cause and severity. Options include:

• Fluid therapy (subcutaneous or IV) for dehydration
• Antiparasitic medications if worms or protozoa are identified
• Antibiotics if a bacterial infection is documented or strongly suspected
• Diet change to a therapeutic gastrointestinal formula
• Antiemetics and anti-nausea treatment if vomiting is present
• Specific management for underlying disease (e.g., thyroid medication for hyperthyroidism, immunosuppressive therapy for IBD)
• Hospitalization and supportive care for severe cases (especially kittens)

Red Flags — Seek Emergency Care

• Repeated vomiting and ongoing diarrhea
• Blood in stool (bright red or tarry black stool)
• Signs of significant dehydration or shock (pale gums, rapid heart rate, collapse)
• Seizures, disorientation, or inability to stand
• Sudden severe abdominal pain
• Very young kitten, very old cat, or immunocompromised cat with diarrhea

Prevention and Follow-Up

• Keep vaccinations current (especially for kittens) — feline panleukopenia vaccine prevents a cause of severe diarrhea.
• Regular fecal checks and deworming as advised by your veterinarian
• Avoid sudden diet changes; transition to new diets gradually over 7–10 days
• Practice good hygiene when handling feces or infected animals
• Follow up with your vet if diarrhea persists beyond 48–72 hours, or sooner if other signs develop

Key Takeaways

• Cat diarrhea ranges from mild to life-threatening; assessment of hydration, behavior, and stool characteristics is critical.
• Mild, short-lived diarrhea in an otherwise bright adult cat can often be monitored with home care and follow-up, but kittens, elderly cats, or animals with systemic signs need prompt veterinary attention.
• Never give over-the-counter human anti-diarrheal medications or start prescription treatments without veterinary guidance.
• Collect a stool sample, keep your cat hydrated, and consult your veterinarian for testing and treatment. Go to emergency care immediately for severe signs such as bloody stool, repeated vomiting, collapse, or significant dehydration.

References

• Merck Veterinary Manual: Diarrhea in Small Animals — https://www.merckvetmanual.com/digestive-system/diarrhea/diarrhea-in-small-animals
• Cornell Feline Health Center: Diarrhea in Cats (feline health topics) — https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/diarrhea

Frequently Asked Questions