Tritrichomoniasis in Cats 🐱💩

By Dr Duncan Houston, BVSc

Tritrichomoniasis is a common cause of chronic diarrhea in young cats and kittens. Caused by the protozoan parasite Tritrichomonas blagburni, this infection can persist for months and is especially common in group settings like catteries or shelters. Thankfully, it's not zoonotic—only cats get it. 🧪

🔬 What Is Tritrichomonas blagburni?

T. blagburni is a microscopic, single-celled flagellated protozoan that lives in the lower intestinal tract. It’s often confused with Giardia under the microscope, but these organisms are unrelated and require different treatments. Proper diagnosis is key. 🧫

🐾 How Is It Transmitted?

• 💩 Fecal-oral route—cats ingest organisms from contaminated surfaces or litter
• 🚽 Shared litterboxes or grooming after stepping in infected feces
• 📆 Parasite can live 3–7 days in the environment

😿 Symptoms to Watch For

The infection is limited to the colon and doesn’t usually cause systemic illness. Most cats appear healthy but have:

• 💩 Persistent or intermittent diarrhea
• 👃 Foul-smelling stools
• 🚽 Frequent defecation or straining
• 🌬️ Excessive gas

In rare cases, dehydration or appetite loss may develop. Otherwise, infected cats are typically bright, hydrated, and eating well. 🐈

🧪 Diagnosis

T. blagburni cannot be detected on routine fecal float tests. Diagnosis requires:

• 🔬 Direct smear – Immediate sample from rectum (low sensitivity)
• 🧫 InPouch culture test – Incubated pouch examined over 12 days
• 🧬 PCR testing – Most sensitive, detects parasite DNA at a reference lab
• 🔍 Biopsy – Rare; only done during colitis evaluation

💊 Treatment Options

The only reliable treatment is ronidazole, a compounded medication not FDA-approved for cats. ⚠️

• 🧴 Must be given in capsule form (tastes bitter)
• 🧤 Handle with gloves—ronidazole is carcinogenic
• 📅 Dosed once daily for 14 days
• ⚠️ Side effects: Neurotoxicity, incoordination, or seizures

Only confirmed cases should be treated with ronidazole. Supportive care includes:

• 🍽️ High-fiber diets
• 🦠 Probiotics to support gut flora

📊 Follow-Up & Monitoring

Negative PCR testing post-treatment does not guarantee clearance. Best practice includes:

• 🧪 PCR test at 2 weeks post-treatment
• 📆 Repeat PCR at 20 weeks
• 🏠 Isolate treated cats to prevent reinfection

Most cats clear symptoms within 2 years even without treatment, but remain infectious to others. 🐾

🧼 Prevention Tips

• 🧽 Scoop litter daily
• 🧴 Disinfect litterboxes regularly
• 🐱 Minimize crowding in multi-cat homes
• 🧪 Test all household cats if one is infected

📱 Ask A Vet App Support

Not sure if your cat’s diarrhea is stress, Giardia, or T. blagburni? Use the Ask A Vet app for:

• 📸 Symptom photo review
• 💬 Ronidazole dosing guidance
• 🧪 Lab test interpretation
• 📋 Dietary recommendations

🏁 Final Takeaway

Tritrichomoniasis causes frustrating, foul-smelling diarrhea in otherwise healthy cats. Accurate diagnosis and careful treatment with ronidazole can resolve symptoms quickly. If your cat has diarrhea that won’t quit—get tested, and get guidance. 🐱💩🧬