Probably the usual sales sites but in the loan section. has she done anything competition wise or been graded if so the relative breed site or BD BS BE may do adverts where people may be looking.
I have a mare that I have on broodmare loan. I found her a home by calling everyone i knew that I thought might like to breed from her. She is a KWPN show jumper and I graded her with the KNN as I used a Knabstrupper stallion for my baby.
You're a little out of season now, best to look late Jan early Feb.
Be very careful though, I had her on loan last year with my foal at foot, they never covered her and I eventually found them half starved to death. I knew something was wrong so I made a surprise visit to find that they had not been feed or watered since I'd left them 13 days earlier. My filly almost died. I obviously had all the excuses every invented but just be aware. Vet them thoroughly and if it doesn't feel right, it probably isn't.
Good luck.
