German Shepherd: Early Sterilization Is Associated with an Increased Incidence of Joint and Urinary Disorders

According to a study* conducted by researchers at the University of California (UC Davis), sterilization of pedigree German Shepherd dogs before the age of one triples the risk of developing one or more joint conditions, such as a tear or rupture of the cranial cruciate ligament and hip dysplasia or elbow dysplasia. In practice, simply delaying sterilization in this breed until after the first year of life—for both males and females—significantly reduces this risk.   The objective of this study was to statistically evaluate the relationships between sterilization at different ages and the onset of joint disorders and cancers in this dog breed. Over a period of fourteen and a half years, the researchers analyzed the medical records of 1,170 pedigree dogs—those that had undergone sterilization or not—who were hospitalized for joint or urinary disorders, or for cancers (osteosarcoma, lymphoma, angiosarcoma, mast cell tumors) previously associated with sterilization or neutering. These various conditions were monitored in affected dogs up to eight years of age, and up to eleven years for females with mammary tumors. These cases were of particular interest for the study because sterilization eliminates male and female sex hormones, which play a key role in the process of closing the epiphyses, thereby disrupting joint alignment in some animals. The dogs were classified into five groups: unsterilized, sterilized before 6 months, sterilized between 6 and 11 months, sterilized between 12 and 23 months (one year), or sterilized between 2 and 8 years. The results show that only 7% of unsterilized males and 5% of unspayed females had one or more joint disorders, compared to 21% of males who have undergone sterilization and 16% of females who have undergone sterilization before the age of one year. The joint disorder most specifically associated with early sterilization or neutering is a torn cranial cruciate ligament, rather than hip dysplasia. A mammary tumor was diagnosed in only 4% of unspayed female dogs, compared with less than 1% of females who underwent sterilization before their first year of age. The incidence of other cancers monitored remained similar across the five groups of dogs. In contrast, urinary incontinence was diagnosed in 7% of females who underwent sterilization before one year of age, whereas this condition did not occur in unspayed females. These findings, which show a significant association between an increase in joint and urinary disorders and early sterilization, should help determine the most appropriate age for sterilization in German Shepherd Dogs and reduce the associated risks.   * Neutering of German Shepherd Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence, Benjamin L. Hart, Veterinary Medicine and Science, May 2016, http://onlinelibrary.wiley.com/doi/10.1002/vms3.34/full