# Cat Diarrhea: When Should You Call the Vet?


## Key Takeaways

- Diarrhea in cats can stem from dietary indiscretion, parasitic infestations (common in kittens and outdoor cats), viral or bacterial infections, stress-induced colitis, or underlying chronic conditions such as inflammatory bowel disease or food allergies.
- Immediate veterinary consultation is indicated for bloody or black, tarry stools (melena), copious watery diarrhea, concurrent vomiting or anorexia, significant lethargy, collapse, or signs of dehydration (pale mucous membranes, poor skin turgor).
- Kittens, senior cats, and cats with pre-existing chronic illnesses are at higher risk for rapid decompensation and require prompt veterinary assessment for any signs of diarrhea.
- At-home management should focus on ensuring hydration, potentially collecting a stool sample for diagnostic testing (e.g., fecal flotation for parasites, PCR panels for infectious agents), and avoiding further dietary manipulation until a diagnosis is established.
- Veterinarians will typically perform a physical examination, assess hydration status, check for abdominal pain, and may recommend diagnostic tests including fecal analysis, blood work (CBC, chemistry panel), and potentially imaging (radiographs, ultrasound) to determine the etiology.
- Preventive measures include gradual dietary transitions, regular fecal parasite screening, and appropriate isolation protocols for newly acquired cats to mitigate disease transmission.

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**Cat diarrhea can come from diet change, parasites, infection, stress, food intolerance, or chronic disease. Call your veterinarian if diarrhea is bloody, watery, repeated, or paired with vomiting, appetite loss, weight loss, or lethargy. Kittens and senior cats can decline quickly.**

## What symptoms or causes should I watch for?

- **Diet change:** New food, treats, milk, or table food can upset a cat's gut.
- **Parasites:** Kittens, outdoor cats, and recently adopted cats may have [intestinal parasites](/knowledge/parasites/pet-parasites/intestinal-parasites-dogs-cats-identification-treatment).
- **Infection:** Viral or bacterial illness can cause diarrhea, fever, and appetite loss.
- **Stress colitis:** Moving, boarding, new pets, or litter box conflict can affect stool.
- **Chronic disease:** Food allergy, inflammatory bowel disease, thyroid disease, or organ disease can contribute.

## What can I safely do at home right now?

- **Save a stool sample:** Ask your clinic whether to bring a fresh sample for testing.
- **Keep water available:** Do not force fluids, but monitor drinking and hydration.
- **Avoid sudden food changes:** Do not keep adding new foods to solve diarrhea.
- **Separate cats if needed:** This helps identify which cat has diarrhea and protects others.
- **Call early for kittens:** Young kittens can dehydrate and become weak quickly.

## When is this an emergency?

Go to an emergency veterinary clinic now if you notice:

- Blood, black stool, or large amounts of watery diarrhea.
- Vomiting plus diarrhea or refusal to eat.
- Weakness, collapse, dehydration, or pale gums.
- Diarrhea in a kitten, senior cat, [or cat](/knowledge/veterinary-medicine/preventive-care/or-cat-logical-health) with chronic illness.
- Weight loss, fever, belly pain, or diarrhea lasting more than a short period.

## What will my veterinarian check?

Your veterinarian may check hydration, weight, temperature, belly pain, stool parasites, diet history, and whether blood work is needed.

## How can I reduce the risk next time?

Change diets gradually, keep parasite checks current, and isolate newly adopted cats until health status is clearer.

## Related veterinary guides

- [Cat Coughing: When Should You Worry?](/knowledge/veterinary-medicine/parasitic-diseases/cat-coughing-when-to-worry)
- [Why Is My Cat Sneezing?](/knowledge/veterinary-medicine/symptom-guides/why-is-my-cat-sneezing)
- Why Is My Cat Drooling?
- [Why Does My Cat's Breath Smell?](/knowledge/veterinary-medicine/dental-care/why-does-my-cats-breath-smell)

## Related Clinical & Scientific Guides

* [My Cat Does Not Cough Up Hairballs](/knowledge/veterinary-medicine/symptom-guides/my-cat-does-not-cough-up-hairballs)
* [Why Is My Cat developing dandruff suddenly? Walking Dandruff Cheyletiella and Diet](/knowledge/veterinary-medicine/symptom-guides/why-is-my-cat-developing-dandruff-suddenly-walking-dandruff-cheyletiella-and-diet)
* [Cat Diarrhea Home Treatment](/knowledge/veterinary-medicine/symptom-guides/cat-diarrhea-home-treatment)


## References

- [Merck Veterinary Manual - Digestive Disorders of Cats](https://www.merckvetmanual.com/cat-owners/digestive-disorders-of-cats/introduction-to-digestive-disorders-of-cats)
- [Companion Animal Parasite Council - Guidelines](https://capcvet.org/guidelines/)
- [AAHA/AAFP - Feline Life Stage Guidelines](https://www.aaha.org/aaha-guidelines/2021-aaha-aafp-feline-life-stage-guidelines/)

*Disclaimer: This article is for educational and informational purposes only. It does not constitute medical advice, does not establish a vet-client-patient relationship, and should not replace an in-person evaluation by a licensed veterinarian.*