snappy west highland terrier!

hello...i'm new here and need some help!
i have an 8month old westie and hes gettin quite snappy, he growls if you try to comb him,stroke him and sometimes just for looking at him! he has snapped on a couple of occasions and i'm worried he's going to get himself into trouble.....he was hand reared as his mother couldnt loook after him...could this be something to do with it? also only one of his testicles has dropped down, which is making think it may be a hormonal problem that he will grow out of. does anyone know whats going on? any suggestions (and any cures you might know) would be VERY much appreciated!

Thank You!!

Hum.. dogs don't usually do that to owners. You sure it's not playful? Have you ever had any dogs.

thanks for all your help

he gets a long walk everyday (i thought it was because he was bored so i extended our usual route) he's quite destructive, he chews tissues,shreds his toys etc. we do have another male dog, but they seem to get on just fine, hes always been a little bit snappy but i first thought it may be due to the fact that he was the runt of the litter and was just used 2 defending himself...but its been going on 4 too long 4 it to be that i think & hes hardly ever alone in the house, he always has company and affection so i really don't know what could be causing this unless its some kind of hormonal thing 2 do with his age? i dont know...i'll keep you posted