PRL and Infertility: The infertile hypothyroid cases showed a significant increase (P > 0.05) in prolactin level (11.01 ± 0.11 Ng/mL) [control 7.27 ± 0.49] and a significant decrease (P > 0.05) in estrogen level (0.05 ± 0 pg/mL) [control 0.2 ± 0.06] compared to control dogs.