I have a 6 month old Lab that at 9 weeks had both testicles. During a routine check up yesterday only one was found. Anyone had this happen? Any possibilities of it dropping again? TIA

The canal usually closes by 4 - 6 months old. So if it is not down now, it wont be coming back down. If the canal isn't closed yet, you have a possibility of it dropping. But I wouldn't depend on that.

If this were me, I'd find a dog chiropractor and see if they can get the 2nd one to drop. I'd do it as soon as possible given the age.