If the horses are/might be IR/PPID, you can create an album in the Photos section of the case history sub-group yourself and upload photos there. Since you already have the case histories for them, I'd just put the photos there. The discussion would also take place on the main group as that's where all the topics are covered for IR/PPID horses.
If not IR and/or PPID, then the album would go here, which is Moderator upload only. You'd need to send the pix directly to me and I can create the album then upload for you.