Acute primary toxoplasmic hepatitis in an adult cat shedding Toxoplasma gondii oocysts

A 3-year-old 4-kg neutered male domestic shorthair cat died within 5 days after onset of fever and respiratory distress. At necropsy, all tissues were icteric, and the liver had a diffuse reticular pattern. Histologically, hepatitis and encephalitis were associated with Toxoplasma gondii tachyzoites. Toxoplasma gondii female gamonts and oocysts were found in epithelial cells of intact villi and in epithelial cells desquamated into the lumen. Finding of acute hepatitis and T gondii oocysts in an adult cat without detectable immunodeficiency is unusual, because adult cats rarely have clinical signs of toxoplasmosis during the oocyst-shedding phase.