feet grow faster than they can be worn down. Without regular trimming, their feet can get too long, eventually splitting, chipping and cracking, which can lead to lameness. Horses subjected to hard work may need horseshoes for additional protection. Some advocates of the barefoot horse movement maintain that proper management may reduce or eliminate the need for shoes, or propose hoof boots as an alternative. Certain activities, such as horse racing and police horse work, create unnatural levels of stress and will wear down hooves faster than they would in nature. Thus, some types of working horses almost always require some form of hoof protection. The cost of farrier work varies widely, depending on the part of the world, the type of horse to be trimmed or shod, and any special issues with the horse's foot that may require more complex care. The cost of a trim is roughly half to one-third that of the cost of a set of shoes, and professional farriers are typically paid at a level commeasurate with other skilled labourers in an area, such as plumbers or electricians, though farriers charge by the horse rather than by the hour. In the United Kingdom, it is illegal for anyone other than a registered farrier to shoe a hoof or prepare the hoof to receive a shoe. It is not illegal in the UK for anyone to trim hooves for maintenance or cosmetic purposes, as long as it is not done preparatory to the application of a shoe. The farrier should have any one of the following qualifications, the FWCF being the most highly skilled: DipWCF (Diploma of the Worshipful Company of Farriers) AWCF (Associateship of the Worshipful Company of Farriers) FWCF (Fellowship of the Worshipful Company of Farriers) In the United States, there are no legal restrictions on who may do farrier work. However, there are professional organizations, such as the American Farrier's Association (AFA), that maintain a voluntary certification program. Levels of certification in the AFA include: CF (Certified Farrier), CTF (Certified Tradesman Farrier), CJF (Certified Journeyman Farrier) For each level of certification, farriers must pass written exams (addressing anatomy, physiology, and biomechanics), forging exams (modifications to keg shoes and building shoes from barstock), and live shoeing exams. Once a farrier has completed the highest level of certification (the CJF), he or she can also pursue Specialty Endorsements, such as the TE (Therapeutic Endorsement). Leg