Cryptorchidism is a condition where one or both testes fail to descend, increasing the risk of tumour development. This study investigated histological and molecular changes in canine cryptorchid testes, focusing on the TRPM8 calcium channel and its potential role in tumour-related signaling pathways. Histological and molecular changes in cryptorchid canine testes, focusing on the role of TRPM8, as well as the expression of PRKCA, MAPK1, and MAPK3 at both mRNA and protein levels, and intracellular calcium ion (Ca2 +) accumulation. Testicular tissues were collected from 14 middle-aged canine, including six with unilateral cryptorchidism. Histological analysis revealed a significant depletion of germ cells and extensive fibrosis in cryptorchid testes. Immunostaining analyses showed reduced expression and altered localization of TRPM8 in cryptorchid testes. Significant differences in TRPM8 transcript level were observed between control scrotal testes and cryptorchid testes, as well as between contralateral and cryptorchid testes (P < 0.01). Western blot analysis revealed a substantial decrease in TRPM8 protein levels (P < 0.001), accompanied by an increase in PKCα and ERK1/2 proteins (P < 0.001) in cryptorchid testes compared to control scrotal testes. Mean fluorescence intensity analysis showed a significantly lower accumulation of intracellular Ca2 + in cryptorchid testes (P < 0.01). The reduced TRPM8 expression and disrupted calcium signaling could activate pro-proliferative PKC/MAPK pathways, promoting tumourigenesis. These results underscore TRPM8’s role in calcium homeostasis and suggest its dysregulation in canine cryptorchidism could predispose to developing testicular cancer. Targeting TRPM8 and related pathways could offer new therapeutic strategies in veterinary and human oncology.