Toxoplasma gondii uses cats as its definitive host, raising welfare questions for both cats and the animals they prey upon, as well as public health considerations.
The welfare dimensions of toxoplasmosis are multifaceted. For cats, toxoplasmosis is rarely a significant welfare concern — most infections are subclinical. For the wildlife prey of free-roaming cats, however, the impact extends beyond predation to transmission of a parasite that can cause neurological disease and death in naive populations. Marine mammals like sea otters that encounter oocyst-contaminated runoff from coastal areas face toxoplasmosis as a significant mortality factor. Responsible cat ownership — keeping cats indoors, managing litter hygienically, testing for toxoplasmosis in cats with neurological signs — addresses both individual cat welfare and the broader ecological and public health footprint of domestic cat populations.