EN
In the years of 1961-1963 serologic examinations were made in 270 dogs with various diseases. In 62 animals there was a positive complement fixation reaction (1:10) with Toxoplasma gondii antigen, the reaction being negative in 173 cases (64%) ; in the remaining dogs (13%) the serum proved to be anticomplementary, even after 3-fold reinactivation at 63°. Most dogs with positive reactions were in the age group of 1-15 years. When passaged in mice, brain cultures from 11 sacrificed dogs with distemper or distemper-like symptoms failed to show the presence of Toxoplasma gondii. Further studies are being led.