TL;DR: Foul-smelling diarrhea in cats is often caused by gut imbalances or parasites and is usually non-emergency unless accompanied by lethargy, vomiting, or blood. Monitor your cat's behavior and take a photo of the stool to help your veterinarian determine the cause.
What causes foul-smelling diarrhea in my cat?
Noticing that your cat has diarrhea is concerning, and an unusually foul odor can make the situation even more distressing. Foul-smelling stool typically occurs when there is an imbalance in the gut flora, the presence of parasites like Giardia, or malabsorption issues where the body isn't properly breaking down nutrients. While unpleasant, the smell is a significant clinical indicator that helps us understand what might be happening in your cat's digestive system.
Is foul-smelling diarrhea an emergency for my cat?
- The urgency level is generally low if your cat is acting normally, staying hydrated, and interested in food.
- You can monitor your cat for 24 hours if they remain playful and active.
- Seek veterinary care if the diarrhea is accompanied by extreme lethargy, persistent vomiting, or a complete loss of appetite.
- Immediate emergency care is necessary if you notice large amounts of bright red blood or black, tarry stools.
Why should I take a photo of my cat's stool for the vet?
- A clear photo of the stool is one of the most helpful tools for a triage professional.
- Visual details like color, consistency, and the presence of mucus or undigested food help identify which part of the intestinal tract is affected.
- A photo helps your veterinarian quickly differentiate between minor dietary issues and more serious conditions for faster treatment.
Clinical Context (Merck Veterinary Manual)
When evaluating feline diarrhea with a foul smell, initial diagnostics should include a complete history and physical examination with rectal palpation and fecal evaluation. Fecal smears should be performed to check for Giardia and fungal elements (Histoplasma capsulatum, Pythium insidiosum). Fecal flotation for parasite identification (Tritrichomonas foetus) and bacterial culture for Campylobacter, Salmonella, and Clostridium are also suggested. Rectal cytology is important to exclude other causes of large-bowel diarrhea, as it can reveal inflammatory cells, neoplastic cells, and infectious agents such as H capsulatum. Suspected clostridial colitis (>5 endospores per field) should be confirmed by identifying Clostridium perfringens enterotoxin A.
Chapter: Gastroenterology, Infectious Disease, Oncology
Source: The Merck Veterinary Manual, 11th Edition (Page 378)