Discovered this a week or so ago. After my two dogs died I was talking about it with my neighbor... (about a half mile away)... and it surprised him because he just had two dogs, (before mine), die as well. We investigated.
Found another neighbor who lost a dog... all of them suddenly and with no apparent sign.
It's not that we didn't know that poison was the culprit but none of us could figure out where, how. After investigating it seems a farmer who leases ground near here.. doesn't live here, had put out varmint poison alongside a ditch bank. Mystery solved.
Yes... the farmer has been warned. - JamesJM
