Abstract
PICO QUESTION: In bitches, does gonadectomy before 1 year of age compared to gonadectomy at 1 year of age or older, increase the risk of cranial cruciate ligament disease during their life? CATEGORY OF RESEARCH: Risk. NUMBER AND TYPE OF STUDY DESIGNS REVIEWED: Eight studies were reviewed, four of which were retrospective cohort studies, two of which were prospective longitudinal cohort studies, one of which was a retrospective case-control study and one of which was a prospective case-control study. STRENGTH OF EVIDENCE: Moderate. OUTCOMES REPORTED: The evidence was mixed, but overall was suggestive that gonadectomy before 1 year of age increased the risk of cranial cruciate ligament disease in bitches. Gonadectomy before 1 year of age was found to increase the risk of cranial cruciate ligament disease in seven of eight studies. Most studies assessed a narrow range of breeds and the generalisability of these results to all dogs is thus limited. The one study which assessed a range of 35 breeds noted an increase in risk of cranial cruciate ligament disease in 6 of 35 breeds associated with gonadectomy before 1 year of age. Direct comparison of studies is limited by the varying age stratifications, breed analyses, and study methodologies. CONCLUSION: Gonadectomy before 1 year of age in Golden Retriever, German Shepherd, and Rottweiler bitches may increase the risk of cranial cruciate ligament disease. In other breeds, limited evidence is available to draw conclusions.