Geographic Variation of Environmental Chemicals and Testicular Pathology in Dogs

Geographical differences in the prevalence of human testicular cancer and poor semen quality may reflect differential exposures to environmental contaminants. Here we report on pathology, histology and chemical content of dog testes from three locations in the UK [West Midlands (WM), East Midlands (EM), South East (SE)] and two in Scandinavia (Copenhagen, Denmark and Vantaa, Finland). Compared to the UK, Vantaa testes had fewer pathologies (p≤0.0001), fewer Sertoli cells and reduced germ cell staining for ‘depleted in azoospermia-like’ (DAZL), and proliferation cell nuclear antigen (PCNA) [p≤0.0001: Sertoli, DAZL, PCNA]. Scandinavian testes had relatively higher PBDE concentrations [Vantaa vs SE and EM (p≤0.01), Copenhagen vs EM (p≤0.05)], lower DEHP concentrations (Vantaa vs UK: WM: p≤0.01; SE p≤0.0001; EM: p≤0.05, Copenhagen vs UK: SE: p≤0.05) and lower PCB concentrations (Vantaa vs UK: WM: p≤0.001, Copenhagen vs UK: WM; p<0.01). Compared to Copenhagen, Vantaa had a lower pathological score (p≤0.05) and reduced DAZL staining (p≤0.05). UK PCB concentrations were greater in WM vs SE (p≤0.01). Both negative and positive correlations were observed between specific chemical types and all three cell markers. Disparities in testicular pathology and morphology across geographical locations may reflect differences in the profile of chemicals detectable in testicular tissue.