This horse model forms part of a model pack I made in Blender 2.5x. A realtime cow is also included in the full model pack and can be downloaded for free from the 'Realtime Ranchers 3D Model Pack' homepage by Lyndon Daniels.
The models also have mouths and partial throats, they come with 2048*2048 color, normal and Ambient Occlusion Maps. This particular model comprises of less than 6000 polys including modelled hair (mane and tail) and occluded geometry (such as the throat and under the hooves). This horse is in obj format with external textures in jpg (so as to reduce bandwidth usage), however the model pack contains lossless png's and also the original .blend files.
You are free to use this model as you please, without limitations.