'To' suggests that the person/animal probably arrives at their destination. 'Towards' simply means in a certain direction, with no indication of whether they arrives there or not. The lion is running {to, towards} the river. Either would be possible here, depending on the situation. The lion is running {to, towards} the prey. 'Towards' is really the only option here. 'To' would suggest that the prey is standing patiently in one spot, waiting for the lion to arrive!