You could try Capri Insurance. Capri Insurance | Provincial Equine Associations Insurance Programs
If they don't have coverage for Whitehorse I'm sure they could tell you who does.
As for coverage it depends on how much you want to pay and the value of your horse. I used to insure mine years ago, had major medical coverage for such things as colic and also had mortality insurance for the value of the horse which at that time was $5500. I cost about $350.00