My understanding of the Sask Law (confirm it yourself)..
Maybe your neighbor will pay greater attention to your request if you showed him pictures of his dogs chasing wildlife and a copy of the regulations.
From the Sask. Wildlife Regulations
https://www.canlii.org/en/sk/laws/re...ghtEdited=true
19(1) Subject to subsection (2.1), no person shall use a dog for hunting big game or wild boar or permit a dog accustomed to pursuing big game or wild boar to run at large in a locality where big game is usually found.
(2) Any dog found chasing big game may be killed by any person without incurring any liability