While it is well documented that horses that are lame or have a diseased hoof will shift weight away from this foot, the way to properly shoe this type of horse always has been up for debate.

Alan Wilson has conducted several studies dealing with horses suffering from laminitis, navicular disease and bone spavin (osteoarthritis of the small tarsal joint). 

“We found that in horses with spavin, the point of zero movement (PZM) is more caudal and lateral than in normal horses, confirming that they change their gait to unload the painful medial aspect of the tarsus,” says Wilson, an equine researcher at Royal Veterinary College in North Mymms, Hatfield, Herts, England.

Are Extensions Beneficial? 

Wilson conducted a variety of studies to determine if wedge extensions were effective in balancing the bony column of a horse with bone spavin. 

First, Wilson and his fellow researchers used a 6-millimeter-thick wedge shoe to alter the foot balance in sound horses with good conformation. As a result, the PZM moved 5 to 10 mm toward the elevated side. However, in another study of sound horses with good conformation, a 20-mm-wide lateral extension was applied to the front and hind feet. The extensions did not alter the PZM. 

To deal with horses suffering from bone spavin, 20-mm-wide extensions and 20-mm-long trailers on the lateral heel were used. 

“(Trailers and extensions) are assumed to act by helping the horse to redistribute its weight on the lateral side of the foot,” Wilson says. “But we have…