Gonadectomy and Its Association with Orthopedic and Neoplastic Disorders: A Retrospective Study in Belgium—Part I (Bitches)

Gonadectomy is performed in bitches to prevent unwanted reproduction and reduce the risk of sex hormone-related conditions. However, growing evidence suggests that the timing of spaying may influence long-term susceptibility to non-reproductive diseases. This retrospective case–control study (2013–2023) evaluated the association between timing of spaying and the development of orthopedic and neoplastic disorders in a Belgian referral-hospital population. Cases included bitches diagnosed with cranial cruciate ligament rupture, hip dysplasia, elbow dysplasia, lymphoma, mast cell tumor, osteosarcoma, or hemangiosarcoma, while disease-free bitches served as controls. Associations between disease occurrence and spaying status were assessed using multivariable logistic regression adjusted for age, weight category, and body condition score. Age at gonadectomy (<12 vs. ≥12 months) and timing relative to the first estrus were evaluated in separate models. Spaying <12 months of age was associated with increased odds of all conditions compared with intact females. Spaying ≥12 months of age was associated with lower odds of several orthopedic and neoplastic outcomes compared with early spaying, although odds were not always comparable to those in intact females. Large body size and higher body condition score were independently associated with increased odds of orthopedic outcomes. These findings support individualized spaying strategies rather than a universal age threshold.