""Dogs are now welcome at Braemar when guests book a private room. A small fee of £5s per dog per night will be charged. Please note that all dogs must be booked in advance to ensure that a dog friendly room is allocated. " according to their SYHA site but No Pets according to the Cairngorm NP site. Try phoning on 01339 741 659
Get an answer from Braemar Youth Hostel staff and past guests.