We should nurture compassionate thought. Since we wish to live, we should not kill any other living being. Furthermore, the karma of killing is understood as the root of all suffering and the fundamental cause of sickness and war, and the forces of killing are explicitly identified with the demonic. The highest and most universal ideal of Buddhism is to work unceasingly for permanent end to the suffering of all living beings, not just humans.
'With the Medicine Buddha mantra you can liberate numberless sentient beings from oceans of suffering and bring them to enlightenment.' - Lama Zopa. Tayata Om Bekanze Bekanze Maha BeKanze Radza Samudgate Soha