If you've ever had a foot corn, you'll know it's painful, and it's most often caused by an ill fitting shoe.
Horses can also get corns. They occur between the wall and the bar, most often on the inside of the front foot. And guess what? They're caused by...
...ill fitting shoes.
And yes, they're painful. Horses with corns are lame and often have to be put on stall rest. And, of course, the ill fitting or poorly placed shoe has to be removed and replaced. A pad is often put on until the corn heals.