There are smooth settings in two places. There is the Smooth Polygons checkbox in the render settings. If checking that doesn't work, then you have smoothing turned off for each body part. Go down thru each body part and look on the properties panel. Smoothing should be checked there and there should be a smoothing angle of 85. You'll have to check (and amend the settings) for each body part of the horse.

If you used Snarlygribbly's Scene Fixer, it's possible you checked "Turn Smoothing Off" for the figure.

Laurie