This sound effect can be found on The Edge Edition Volume 1, which was made by The Hollywood Edge. It's the 5th whinny from Horse Whinnies Group AT045501 and Horses Several Whinn PE025201, which can be found on Animal Trax and The Premiere Edition Volume 1, respectively. Links: https://soundeffects.fandom.com/wiki/Hollywoodedge,_Horses_1_High_Pitched_TE016301#Audio_Samples