ABSTRACT
The effect of infection of T.canis infective larvae were investigated on social [intermale] aggression and maternal aggression in mated male and lactating female mice. It has been shown that such infection produced a significant inhibition, mainly of maternal aggression parameters and on offensive behaviours category which associated with this form of fighting. Infection with 4000 infective larvae of T.canis has however no significant effect on most parameters of social aggression in mated male mice. The suppressive effects on maternal fighting could be attributed to the fact that lactating females were more susceptible to this stage of infection. The muscular tone data in this study excluded the involvement of myorelaxation in the suppression of maternal aggression. Postmortem investigation of mated and lactating mice, shows the presence of substantial number of T.canis larvae which managed to migrate to the brain