Most cats infected with Toxoplasma gondii never show any signs of illness at all. The parasite typically causes disease only when a cat’s immune system can’t keep it in check, which means the symptoms you’d watch for depend heavily on your cat’s overall health. When toxoplasmosis does cause illness, it most commonly shows up as fever, loss of appetite, and lethargy, but it can also target the eyes, lungs, liver, and nervous system in ways that look very different from one cat to the next.
The Most Common Signs
The earliest and most frequent symptoms of active toxoplasmosis are vague: your cat stops eating, feels warm, and seems unusually tired. These signs overlap with dozens of other conditions, which is part of what makes toxoplasmosis tricky to spot at home. A cat that’s normally enthusiastic about meals but suddenly turns away from food for more than a day or two, especially combined with low energy, is worth a vet visit regardless of the underlying cause.
Eye and Neurological Symptoms
Toxoplasmosis has a particular tendency to affect the eyes and brain. In the eyes, it causes inflammation of the inner structures (a condition called uveitis), which you might notice as cloudiness, a change in eye color, pupils that look different sizes or have an irregular shape, or sensitivity to light. Some cats go partially or fully blind. If your cat starts bumping into furniture or misjudging jumps, eye involvement is a possibility.
Neurological symptoms can be more dramatic and alarming. These include loss of coordination, walking in circles, pressing their head against walls or furniture, twitching ears, personality changes, seizures, difficulty chewing or swallowing, and loss of control over urination or defecation. Heightened sensitivity to touch, where your cat flinches or reacts strongly to being petted, is another neurological sign. Any of these warrant immediate veterinary attention.
Lung and Liver Involvement
When the parasite settles in the lungs, it causes a form of pneumonia. You’ll notice your cat breathing harder or faster than usual, and the difficulty tends to worsen gradually over days rather than appearing all at once. Open-mouth breathing in a cat is always a red flag.
Liver involvement produces jaundice, a yellowish tinge to the skin, gums, and the whites of the eyes. This is easiest to spot by lifting your cat’s lip and looking at the gums, or by checking the inner surface of the ears where the skin is thinnest. Jaundice in a cat is never normal and always signals a serious problem.
Which Cats Are Most at Risk
Healthy adult cats with strong immune systems almost always fight off the parasite without ever getting sick. The cats most vulnerable to clinical disease are kittens, elderly cats, and those with compromised immune systems from conditions like feline immunodeficiency virus (FIV) or feline leukemia virus (FeLV). If your cat has one of these underlying conditions and develops any of the symptoms above, toxoplasmosis should be on the list of possibilities your vet investigates.
Outdoor cats and those fed raw meat diets face a higher risk of exposure. Cats pick up the parasite by eating infected prey (birds, rodents) or undercooked meat containing tissue cysts. Indoor-only cats eating commercial food have a much lower chance of encountering the parasite in the first place.
How Vets Diagnose Toxoplasmosis
There’s no single definitive test that gives a quick yes-or-no answer, which is one of the frustrating realities of this disease. Diagnosis typically involves blood tests that measure antibodies your cat’s immune system produces against the parasite. Two types of antibodies matter most: IgM antibodies, which suggest a recent or active infection, and IgG antibodies, which indicate exposure at some point (but can take four to six weeks to appear after infection).
About 80% of infected cats develop IgM antibodies, and all infected cats eventually produce IgG antibodies. The catch is that having antibodies alone doesn’t prove toxoplasmosis is causing your cat’s current symptoms. Many healthy cats test positive for antibodies simply because they were exposed in the past and fought it off. What raises suspicion is a very high antibody level, or a level that rises significantly when tested again two to three weeks later.
In practice, vets often reach a tentative diagnosis by combining several pieces of evidence: rising antibody levels, ruling out other conditions that could explain the symptoms, and watching whether the cat improves on anti-parasitic medication. If your cat gets better with treatment, that response itself supports the diagnosis.
What Treatment Looks Like
The standard treatment is an antibiotic given orally, typically for four to six weeks, followed by a reassessment. Most cats with mild to moderate disease respond well and recover, though cats with severe neurological or eye damage may have lasting effects. Your vet will likely want to recheck your cat’s bloodwork and symptoms before deciding whether to continue or stop medication.
Cats with compromised immune systems may need longer courses of treatment and have a less predictable recovery. The underlying immune condition often determines the long-term outlook more than the toxoplasmosis itself.
Protecting Yourself During Your Cat’s Infection
If you’re concerned about catching toxoplasmosis from your cat, the practical risk is lower than most people assume. Cats shed the infectious form of the parasite in their feces for a limited window, typically just one to two weeks after their initial infection. After that, most cats never shed again. More importantly, the parasite in fresh feces isn’t immediately dangerous. Oocysts need one to five days sitting in the environment before they become infectious, so cleaning the litter box daily effectively eliminates the risk of transmission through that route.
If you’re pregnant or immunocompromised, have someone else handle litter box duties as an extra precaution. Wear gloves if you must do it yourself, wash your hands thoroughly afterward, and scoop daily. The same parasite is also found in undercooked meat and unwashed garden produce, which are actually more common sources of human infection than cat ownership.