JAVMA • Vol 248 • No. 2 • January 15, 2016 In ancient Rome, during the First Century CE, Lucius Columella wrote that it was proper to remove the tails of puppies to prevent their growth to an “abominable length” and to prevent madness, which is presumed to refer to rabies.1 Although the idea that this procedure could protect dogs against rabies has long since been abandoned, tail docking is still commonly performed, both because of a belief that it reduces the incidence of injuries and because of the resulting perceived improvements in aesthetics. However, the effectiveness of this procedure in preventing injuries has been questioned, and the idea of performing this and other surgical procedures on animals solely for cosmetic reasons has been heavily criticized in many parts of the world.2 In fact, some countries have passed legislation restricting these types of surgeries. While anecdotal reports suggest that certain cosmetic procedures such as ear cropping are in decline in North America, to our knowledge there are no reliable estimates on the numbers of these procedures performed annually. Most surgical procedures performed on dogs and cats in North America are performed for therapeutic, diagnostic, or preventive purposes; that is, they are medically necessary. In contrast, procedures that are not necessary for maintaining health or that are not beneficial to the animal can be classified as MUSs. This would include procedures performed mainly to alter the appearance of animals (eg, ear cropping and tail docking in dogs), procedures performed solely to prevent behaviors that are destructive or annoying (eg, devocalization and defanging in dogs and onychectomy in cats), and procedures of dubious or minimal benefit (eg, dewclaw removal in dogs). Note that elective neutering of healthy dogs and cats has historically been performed to prevent or reduce the risk of future health problems (eg, pyometra, mammary gland neoplasia, and reproductive tract–related neoplasia) and to prevent unplanned breeding, which benefits the population as a whole by reducing the number of unwanted animals.3 Thus, for the purposes of the A review of medically unnecessary surgeries in dogs and cats