that female dogs be spayed no earlier than 3 to 4 months of age. A later study comparing female dogs spayed between 4 and 6 months and after 6 months showed no increased risk.

One study showed the incidence of hip dysplasia increased to 6.7% for dogs neutered before 5.5 months compared to 4.7% for dogs neutered after 5.5 months, although the cases associated with early age neutering seems to be of a less severe form. There was no association between age of neutering and arthritis or long-bone fractures. Another study showed no correlation