EVALUATION OF ENVIRONMENTAL FACTORS ON CANINE REPRODUCTION AND FERTILITY: INNOVATIVE STRATEGIES

Fertility assessment is challenging both in human and canine species because it is defined by a combination of numerous genetic and environmental factors. In recent decades, a decline in humans fertility occurred and was related to environmental pollutants, such as endocrine disruptor chemicals (EDCs), that increased dramatically as result of technological development. Living close to their owners, dogs are exposed to similar risks whose impact on their reproduction is still unclear. Many widespread compounds may interfere with canine reproductive health from embryonic development up to conception. Since environmental hazards in dogs are poorly understood, this PhD thesis comprises four studies devoted to exploring their consequences on canine reproduction and fertility. The first two projects were centered on the exposure of breeding dogs to cigarette smoke. Cotinine was applied as marker of nicotine intake in male dogs and pregnant bitches belonging to smoking and non-smoking owners. Significant differences were highlighted between exposed and non-exposed dogs, however measurable levels of this metabolite were detected in serum, semen, hair, and amniotic fluid of all enrolled patients. Despite nicotine metabolites increase seminal oxidative stress, in our caseload the level of total antioxidant capacity (TAC) in ejaculate didn’t correlate with male dogs’ exposure to tobacco smoke. Albeit the practical effects of passive smoke should be investigated on a larger sample size, results obtained demonstrated a non-negligible exposure that could interfere with dogs’ reproductive performance. Apart from tobacco smoke consequences, within other two studies we focused on cryptorchidism. Through the application of immunohistochemical techniques and miRNomics, we found precancerous lesions and molecular dysregulation in both retained and scrotal gonads of affected patients. Interesting implications have emerged from this outcome especially concerning testicular neoplastic predisposition and the appropriate therapeutic approach in unilateral cryptorchids. In addition, molecular pathways suggested an abnormal expression of estrogen receptors that, as assumed in humans, may justify a greater sensitivity to EDCs even in cryptorchid dogs. Regardless some limitations, the overall outcomes of the present doctoral dissertation pointed out the environmental role on canine reproduction. Although pollutants’ effects can’t be completely eliminated, greater awareness should be placed on common bad habits like cigarette smoke which could impair fertility potential even in “man’s best friend”.