http://en.wikipedia.org/wiki/Icelandic_horse
Hmm, reading the breed's characteristics from the article it seems like the perfect horse for Skyrim.
Some snippets for the lazy:
-Developed from ponies taken to Iceland by Scandinavian settlers in the 9th and 10th centuries.
-Icelandic horses weigh between 330 and 380 kilograms (730 and 840 lb)[1] and stand an average of 13 and 14 hands (52 to 56 inches, 132 to 142 cm) high,
-...theory suggests that the breed's weight, bone structure and weight-carrying abilities mean it can be classified as a horse, rather than a pony.
-The breed comes in many coat colors, including chestnut, dun, bay, black, gray, palomino, pinto and roan.
-The breed is known to be hardy and an easy keeper.
-The breed has a double coat developed for extra insulation in cold temperatures.
-Their most productive years are between eight and eighteen, although they retain their strength and stamina into their twenties.
Now just take all of those characteristics and put them in a Clydesdale size package and we got our horses for Skyrim.