Toxoplasma gondii is a single-celled parasite that infects almost half of all outdoor cats during their lifetime — but most cats clear it without ever showing a sign. When clinical disease does develop, it tends to hit young cats, FIV/FeLV-positive cats, and cats on immunosuppression hard, with respiratory, neurologic, or liver involvement. It's also the parasite behind the pregnancy warnings about litter boxes.
Last reviewed: May 2026
What Toxoplasma Is
Toxoplasma gondii is a protozoan parasite that uses cats as its only definitive host — meaning cats are the only species in which the parasite reproduces and sheds infective eggs (oocysts) in feces. Cats become infected by eating wild prey, raw meat, or contaminated soil. After a 3- to 10-day shedding window — which only happens once in the cat's lifetime — the parasite forms cysts in muscle and nervous tissue and is hidden from the immune system for years.
About 30 to 60 percent of outdoor cats have antibody evidence of past Toxoplasma exposure. Indoor-only cats fed cooked or commercial diets have rates closer to 5 to 10 percent.
Signs of Clinical Toxoplasmosis
Most infected cats never get sick. When clinical disease develops, signs depend on which organ the parasite invades:
- Respiratory: fever, lethargy, coughing, rapid or labored breathing (pneumonia)
- Neurologic: seizures, head tilt, ataxia, behavior changes, weakness
- Ocular: uveitis (cloudy eye, redness, squinting), iris inflammation
- Hepatic: jaundice, vomiting, decreased appetite
- Generalized: fever, weight loss, enlarged lymph nodes
Young kittens and cats coinfected with FIV or FeLV are most at risk, as discussed in the AAFP Feline Retrovirus Guidelines, 2020. Adult immunocompetent cats are usually able to wall off the parasite without symptoms.
How Vets Diagnose Toxoplasmosis
Diagnosis is challenging because antibody tests (IgG, IgM) only indicate exposure, not active disease. A 4-fold rise in IgG titer between two samples taken 2 to 3 weeks apart, paired with compatible clinical signs, is the most reliable diagnostic combination. PCR on cerebrospinal fluid, aqueous humor, or affected tissue can identify active infection. Bloodwork often shows liver enzyme elevation; thoracic radiographs may show a diffuse interstitial pattern in pulmonary toxoplasmosis.
Treatment
Clindamycin at 10 to 15 mg/kg orally every 12 hours for 4 weeks is the standard treatment. Most cats with respiratory or hepatic involvement improve within 48 to 72 hours. Neurologic and ocular involvement may need 6 to 8 weeks of therapy and topical eye medications. Supportive care includes anti-nausea medication, hydration, and treating any concurrent infection or immunosuppression. Recovery is good in immunocompetent cats but guarded in retrovirus-positive cats, per the AAFP-AAHA Feline Life Stage Guidelines, 2021.
Risk to People — The Pregnancy Warning Explained
Toxoplasma is the parasite behind the long-standing advice that pregnant women shouldn't handle litter boxes. The actual risk picture is more nuanced: cats only shed infective oocysts during a single 3- to 10-day window in their lifetime, and oocysts need 1 to 5 days in the environment to become infective. Daily litter box cleaning effectively prevents transmission. Far more human Toxoplasma infections come from undercooked meat and unwashed produce than from cats.
That said, pregnant and immunocompromised people should follow common-sense precautions: have someone else change the litter box daily; if you must do it yourself, wear gloves and wash hands thoroughly; keep cats indoors and feed only commercial or cooked diets; and avoid handling stray cats.
Prevention in Cats
Keep cats indoors and feed only commercial or thoroughly cooked food. Avoid raw meat diets, which are a major source of Toxoplasma exposure. Manage outdoor mouse and bird hunting. Test FIV/FeLV status before bringing any new cat into a household. There is no Toxoplasma vaccine for cats.
When to See a Vet
Toxoplasmosis is hard to recognize from outside the body. Most red flags are systemic illness in a cat with risk factors.
Call your vet today if:
- Fever, lethargy, and decreased appetite for more than 24 hours
- New cough or rapid breathing in a cat with outdoor or raw-food exposure
- Squinting, cloudy eye, or visible third eyelid
- FIV/FeLV-positive cat showing any new illness
- Immunosuppressed cat (chemotherapy, steroids) with vague illness
Go to the ER immediately if:
- Seizures, sudden disorientation, or collapse
- Severe respiratory distress
- Severe jaundice or vomiting blood
- Sudden blindness or one-eye blindness
- Profound lethargy combined with fever
What's going on with your pet?
Describe symptoms or snap a photo. Voyage tells you urgency, home care, and whether you need a vet.
First, tell us about your pet
Breed and age make a real difference in how Voyage interprets symptoms.
Describe the symptoms
🏆 Outperforms ChatGPT & Gemini · 🩺 Vet-grounded · 🔒 Private
Love it? See everything Voyage can do
Frequently Asked Questions
Can I catch toxoplasmosis from my indoor cat?
The risk is very low. Indoor cats fed commercial or cooked food rarely encounter the parasite. Even cats that have been exposed only shed oocysts once in their lifetime, for 3 to 10 days, and oocysts take 1 to 5 days in the environment to become infective. Daily litter-box cleaning eliminates almost all risk. Most human cases come from undercooked meat, not cats.
How much does diagnosing toxoplasmosis cost?
A vet visit plus paired serology and bloodwork typically runs $300 to $700. Adding chest radiographs or ocular workup brings the total to $500 to $1,000. Specialized PCR testing (CSF or aqueous humor) at a referral center runs $300 to $600 more. Clindamycin treatment itself is inexpensive — typically $30 to $80 per month.
Should pregnant women rehome their cats?
No. Major obstetric and infectious disease organizations agree that there's no reason to rehome a healthy indoor cat during pregnancy. Have someone else handle the litter box if possible, or use gloves and wash hands carefully if you must clean it yourself. Keep cats indoors and avoid feeding raw meat. The increased risk is small with these precautions in place.
Can outdoor cats be tested for active shedding?
Fecal testing during the brief shedding window can identify oocysts, but cats shed only once in their lifetime and the window is narrow. Routine fecal testing is generally not recommended — most positive tests reflect past exposure rather than active risk. Keeping cats indoors and feeding commercial diets is more effective than testing.
How long does treatment take to work?
Most cats with respiratory or hepatic toxoplasmosis improve dramatically within 48 to 72 hours of starting clindamycin. Ocular and neurologic disease may take 1 to 2 weeks to show improvement and 6 to 8 weeks of treatment to clear. Permanent damage can remain after the parasite is controlled, especially in eye and brain involvement.
Still Not Sure if Your Cat Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share photos of breathing rate, the eyes, and any neurologic changes, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.