While small dogs and cats can survive comfortably with three legs, larger dogs, horses, and farm animals require the limb to support their weight. Surgery has also been done on birds that are used for breeding purposes. Each prosthetic limb is custom-made to fit the individual needs of the specific animal. Dudley (above) lost a leg as a wee duckling when attacked by aggressive chickens. While he could still swim, Dudley had trouble getting around on land. So, mechanical engineer Terence Loring partnered with 3-D printing company Proto3000 to help fabricate an artificial leg. Continue reading for more.