What are the laws regarding what LEGAL actions you can take – where you live? If you have no animal control officers -(who can or will come pick them up) then surely – if they are a real menace, you can choose to some action within the law, to either trap them or to kill them. Be advised POISON can be ingested or consumed by anyone or anything and will KILL indescriminately.
In the ranch & livestock areas of the USA – people are legally allowed to shoot dogs going after their livestock. (But most are good shots, and if you aren’t – you may hit somebody or something you did not INTEND to.)
I carry mace or pepper spray when I go on walks in case or loose or feral dogs and I have had to use it (3 times) and it worked VERY WELL, without any long term damage to the dogs in question.