PiRNAs are a subclass of non-coding RNAs, 26-31 nucleotides (nt) in length, that form regulatory complexes through their interaction with PIWI proteins. Studies in model organisms have demonstrated that piRNAs play crucial roles in tissue development and in predicting disease outcomes, positioning them as promising targets for developmental regulation and therapeutic intervention. In contrast, research on piRNAs in animal husbandry is still in its early stages and has not received sufficient attention. Despite this, the few studies available in livestock research have revealed that piRNAs serve as key regulators of reproductive development, underscoring their significant regulatory potential in farm animals and justifying further investigation. Accordingly, this review uses the bovine mammary gland as an exemplary case to summarize the progress in piRNA research related to mammary development and disease. The role of piRNAs in regulating breast cancer stem cell proliferation and modulating inflammatory progression is a highly active area of research. We hypothesize that piRNAs may play a potential role in regulating both mammary gland development and mastitis, making them promising targets for enhancing mammary development and overall health in dairy cattle and providing a theoretical foundation for further piRNA applications in animal husbandry.