Going bald!

[Annagain]

My boy seems to be going bald! He has virtually no hair between his back legs and around his sheath and it's starting to spread down his back legs. There's no rash, scabs or inflammation and it doesn't seem to bother him but it is quite warm there - I think because the blood vessels are so close to the skin there and there's no coat to insulate it - and he gets very foamy and sweaty there as there's no coat to absorb the sweat. I'm not overly worried as it doesn't seem to bother him and I have heard of seasonal alopecia - but I believe that's normally losing the winter coat before the summer one grows rather than the other way round? I've asked the YO, other liveries, farrier and my instructor and nobody has seen anything like it, but they all agree it doesn't look sinister. I'm very aware he's an older (17) grey though, so anything skin related could be more serious than in a bay/chestnut horse?

Has anybody come across this before?

 

[Sugar_and_Spice]

Could it be some sort of bacterial or fungal infection attacking the hair root? Because he gets sweaty there maybe, things like to multiply in warm damp conditions I think? It doesn't sound as if your horse has this, but some horses with ringworm (a fungal infection) lose small round patches of hair and sometimes it doesn't regrow after the infection has cleared.