Finding horse miniatures to compliment the fantasy miniatures can be somewhat difficult at times. One solution is to look in children's toy stores for the Toob collections. They have tubes of animals, dinosaurs, etc. I was fortunate enough to find one just of various breeds of horses that work well with the 25mm miniatures.
Figures shown to illustrate how well these horses match the 25mm scale. Undead included because it is International Be Kind To The Un-Living Week (somewhere, maybe).