Definitely not just a "male Greyhound thing" I'm thinking maybe anal glands, too. If that is the case, pop into your vet's & ask that they "express"
them....my vet does this on a walk-in basis, no apptmt needed. Vet tech can do it & tell you if they are very full, or even infected. You can do it yourself
if you know what you're doing, but it grosses me out so bad, I leave it to the professionals.
Good luck.