Ovine abortion and neonatal death due to toxoplasmosis in Montana.

Of 33 ewes in a flock in Montana, 6 aborted or gave birth to weak lambs, which died within 2 days after birth. Two lambs and a placenta from 1 ewe as well as 1 lamb from another ewe were submitted for diagnosis. Focal necrotizing placentitis, focal pneumonia, focal hepatitis, focal interstitial nephritis, and focal nonsuppurative encephalitis were seen in tissue sections from 2 of the lambs. Toxoplasma gondii was found in smears and sections of the placenta and in sections of lung from 1 lamb. Mice inoculated with tissues from a lamb developed dye test antibodies to T gondii. Eleven of 12 ewes from the same flock had dye test antibody titers of 1:16 or more, and titers were 4-fold higher in aborting ewes than in ewes with normal lambs.