Lesions of neonatally induced toxoplasmosis in cats

Five pregnant queens were inoculated orally with Toxoplasma gondii tissue cysts. Twenty-two live and three dead kittens were born 16 to 31 days after inoculation. Four kittens were eaten by queens and, thus, were not available for histologic examination. Twenty-one kittens that died or were euthanatized on day 2 (two kittens), 4 (one kitten), 5 (five kittens), 6 (five kittens), 7 (one kitten), 8 (four kittens), 16 (two kittens), and 29 (one kitten) after birth were studied histologically. T. gondii was detected by bioassay and was seen in histologic sections of tissues from all 21 kittens. The histologic lesions associated with neonatal toxoplasmosis were widely disseminated infiltrates of macrophages and neutrophils often accompanied by necrosis; lymphocytes and plasma cells were occasionally present. The most consistent lesions were proliferative interstitial pneumonia (21/21); necrotizing hepatitis (20/21); myocarditis (21/21); skeletal myositis (21/21); glossal myositis (19/19); nonsuppurative encephalitis affecting the cerebrum (18/18), brain stem (15/15), and spinal cord (9/9); uveitis (19/19); necrotizing adrenal adenitis (18/18); and interstitial nephritis (16/21). Placental lesions (2/2) consisted of grossly visible areas of necrosis and mineralization.