Age-related canine reproductive health: Impact on fertility and disorders

다국어 초록 (Multilingual Abstract)

Importance: Advances in veterinary care and the greater concern for animal welfare have extended dog lifespans, leading to an increase in age-related reproductive disorders and infertility that negatively impact health and breeding. Unlike in humans and laboratory models, canine reproductive senescence remains underexplored. A comprehensive understanding of these processes is essential for improving reproductive health care among aging populations, breeding management, and comparative aging research.
Observations: Canine aging impairs reproductive homeostasis with endocrine disruption, structural remodeling, and molecular inflammation. In females, these changes manifest as prolonged interestrus intervals, silent estrus, persistent progesteronemia, decreased oocyte quality, increased risk of cystic endometrial hyperplasia, pyometra, and mammary tumors. Molecular alterations include gonadotropin signaling, mitochondrial dysfunction, and pro-inflammatory microRNA profiles. In males, reproductive decline is characterized by reduced testosterone secretion, degeneration of the seminiferous epithelium, and interstitial fibrosis, often associated with oxidative stress and apoptosis. The effects of aging are prone to various clinical conditions, including benign prostatic hyperplasia, prostatic tumors, and testicular tumors. Collectively, these alterations reduce conception rates, litter size, and compromise sperm quality.
Conclusions and Relevance: This review summarizes current knowledge on reproductive aging in both sexes of dogs, with a focus on the mechanisms that impair fertility and promote disease. Addressing its clinical implications through routine reproductive screening in older dogs could allow for earlier diagnosis and treatment, including fertility preservation.