i agree with Jeff, a k9 would catch scent and alert as easily if not more so
than the horse in rain/snow conditions. Breezy conditions would be
advantageous, but airscent dogs range an area (zigzagging and/or in a
circular
pattern) adding to the coverage from horseback and would most times manage
to get
downwind in, for example, forested areas where it is hard to get off trail.