The UC Davis study looked at the health records of 759 Golden Retrievers. Goldens were chosen because they are one of the most popular breeds in the U.S. and Europe, are often used as service dogs, and are also susceptible to various cancers and joint disorders.
The intent of the study was to investigate the effects of neutering on the risks of several diseases in a single breed of dog, distinguishing between males and females, and between dogs that had been neutered or spayed early (before one year), late (after one year), or not at all.
The dogs ranged in age from 1 to 8 years and had been seen at UC Davis? William R. Pritchard Veterinary Medical Teaching Hospital for one or more of the following problems: hip dysplasia (HD), cranial cruciate ligament (CCL) tear, lymphosarcoma (LSA), hemangiosarcoma (HSA), and mast cell tumor (MCT).
The researchers focused on joint disorders and cancers because neutering or spaying removes the testes or ovaries and disrupts production of hormones that play important roles in body processes like bone growth plate closure.