Introduction

Toxoplasmosis is an infectious disease caused by the microscopic single-celled parasite Toxoplasma gondii. Cats hold a unique role in the lifecycle of this parasite, serving as the definitive host—meaning the parasite can only complete its reproductive lifecycle within the feline intestinal tract. Most cats contract the parasite by hunting and consuming infected intermediate hosts, such as rodents or birds, or by eating raw, undercooked meat. While the vast majority of healthy adult cats will show absolutely no clinical signs of illness after exposure, toxoplasmosis can cause severe, systemic disease in young kittens, immunocompromised cats, or older felines.

Toxoplasmosis

  • Common Signs: The vast majority of cats are completely asymptomatic. When clinical illness (toxoplasmosis) does occur, the symptoms depend entirely on which organ systems the migrating parasites invade. Signs can be vague and generalized, including profound lethargy, a complete loss of appetite, fever, and unexplained weight loss. If the parasite invades the lungs, you may see coughing or rapid breathing. Liver involvement can lead to jaundice (yellowing of the eyes and gums), while central nervous system involvement can cause staggering, behavioral changes, seizures, or vision loss due to severe eye inflammation (uveitis).
  • Recommended Diagnostics: Diagnosing toxoplasmosis requires a comprehensive approach. A complete blood count (CBC), blood chemistry panel, and urinalysis are baseline steps to evaluate organ function. The definitive test is toxoplasmosis antibody testing (IgG and IgM titers), which can distinguish between a past, dormant exposure and an active, acute infection. Depending on clinical signs, advanced imaging, such as chest X-rays or abdominal ultrasounds, may be required to assess damage to specific organs.
  • Treatment: Requires a specialized course of antiparasitic medications, most commonly clindamycin or a combination of other targeted antibiotics, administered for several weeks. Alongside the direct treatment of the parasite, rigorous supportive care—such as intravenous fluids, nutritional support, and anti-inflammatories to manage eye or neurological complications—is often critical. Cats that are diagnosed and started on targeted treatment early in the disease process generally respond very well.
  • Prevention & Human Health Considerations: Prevention largely centers on diet and lifestyle. Feed your cat only commercial, cooked diets and explicitly avoid raw meat diets. Keeping cats exclusively indoors is the most effective way to prevent them from hunting infected prey. While humans can contract toxoplasmosis, the risk of acquiring it directly from petting or handling a household cat is exceptionally low, as cats rarely carry the parasite on their fur. Human transmission is far more likely through handling raw meat or unwashed garden vegetables. However, pregnant women and individuals with compromised immune systems should take precautions: avoid cleaning the litter box, or if necessary, wear gloves, wash hands thoroughly, and scoop the box daily (before the shed parasite becomes infectious).

This blog is for informational purposes only and is not intended to provide diagnostic or treatment guidance. If you have any concerns about your pet’s health, please contact Cascade Heights Veterinary Center directly by phone at 206-403-1108,  email, or by scheduling an appointment.  Medications, supplements, and prescription diets can be conveniently ordered through our online pharmacy.