Non-neoplastic and neoplastic disorders linked to desexing in dogs

Surgical sterilisation is a common tool in most of the developed world for combatting the overpopulation of unwanted dogs and eliminating the risk of reproductive diseases in pet dogs. Luteinising hormone (LH) stimulates the secretion of gonadal steroid hormones, which negatively feedback to the hypothalamus and anterior pituitary to decrease the secretion of GnRH and LH, respectively. However, in the desexed mammal, there is no negative feedback of LH, which results in supraphysiological circulating concentrations. LH receptors in non-reproductive tissues may induce cell division and stimulate nitric oxide release. With constant activation following gonad removal, these receptors are upregulated, further magnifying the effects of the supraphysiological LH concentrations in non-reproductive tissues. Non-reproductive long-term health complications resulting from canine desexing are discussed, as well as how these effects are mediated by LH receptor activation in non-reproductive target tissues.