If the deer squatted--it sounds like you might have hit him a liitle far back-How long did you wait before goin after him? The trail will probably be easier in the morning. Besides blood look for tracks that are really dug in. Sound like if he was spraying he must have had a major blood vessel broken--if you lose the trail and have some friends start searching in grid pattern formation--don't neglect thinkin about him doubling back or going uphill--If he is mortally wounded (which it sounds like)--he probabaly dove strait thru a thick briar patch and is laying dead on the other side--in the dark its easy to miss'em flashlights or not--use your nose as well--good luck