Neoplastic Conditions Associated with Spay/Neuter Status in the Canine

Neoplasia, including malignant and non-malignant tumors, represents the single most important group of diseases in both veterinary and human medicine today. Recent studies have shown that cancer is the cause of death for 15-30% of dogs and 26% of cats. As a consequence, a large body of research focuses on the causes, diagnosis and treatment of this diverse group of conditions. As the study of cancer in pets evolved, it was quickly recognized in the 1960’s that some cancers were related to the presence or absence of a dog’s reproductive tract. A series of studies demonstrated that vaginal tumors, uterine tumors, ovarian tumors and mammary tumors could all be substantially reduced or eliminated by removal of the ovaries and uterus or of the ovaries alone.1,2 As a consequence of this work, and the wide-spread adoption of spay-neuter programs in the USA, these tumors represent a very small percentage of disease in this country. In contrast to this, mammary tumors represented the most common tumor submitted for histopathology in a Norwegian study. Mammary tumors accounted for 30% of submissions - approximately 9-13% of dogs - and 94% were malignant or pre-malignant based on modern criteria.3 Separately, mammary tumors were among the two main reimbursement claims in female dogs (the other was pyometra) in a recent Swedish study.4 ...