Toxoplasmosis in Dogs

Toxoplasmosis is caused by Toxoplasma gondii, a microscopic protozoal parasite that infects people and other warm-blooded animals. It is found worldwide.

Cats (both wild and domestic) are the only hosts, meaning the parasite must live in cats to complete its life cycle. Cats are also the main source of infection for other animals and people. In dogs, the parasite can spread through the body. 

Healthy adult animals with strong immune systems usually control the infection and show no signs. However, in puppies, the parasite can spread widely and cause serious illness, including fever, diarrhea, coughing, breathing difficulty, yellowing of the skin and eyes, seizures, and possibly death. Adult animals with weakened immune systems are also at high risk for severe, sudden disease.

In many cases, treatment isn't needed. When necessary, veterinarians might prescribe antibiotics to control the infection. Seizures can be managed with medications, and severely ill or dehydrated animals can require IV (intravenous) fluids and supportive care in the hospital.

Toxoplasmosis is also important in human health. Toxoplasmosis is especially dangerous for people with weakened immune systems, in whom it can affect the nervous system. It is also a major concern during pregnancy because the parasite can cross the placenta and cause birth defects.

People can become infected by eating undercooked infected meat or accidentally ingesting microscopic parasite eggs in cat feces.

Prevention includes thoroughly washing hands, utensils, and surfaces after handling raw meat, and cooking meat to at least 152.6°F (67°C). Freezing meat or exposing it to gamma radiation can also kill the parasite. Pregnant women should avoid handling cat litter, soil, and raw meat when possible. Cats should be fed only cooked or commercial food, and litter boxes should be cleaned daily (preferably by someone who isn't pregnant). Gloves should be worn while gardening, and vegetables should be washed thoroughly before eating.