Pulsed electromagnetic field (PEMF) therapy, a commonly used supplementary treatment in the horse industry, shows promise in enhancing circulation, reducing inflammation, and supporting cellular repair; however, its effects on equine physiology remain unclear. Limited research and inconsistent protocols create uncertainty about its efficacy and safety in horses. Our study evaluates the short-term effects of PEMF on hematological and biochemical parameters in horses. Five active sport horses underwent PEMF therapy for five consecutive days using a full-body blanket at specific frequencies. Blood samples were collected both before and after treatment to assess 72 hematological, biochemical, and endocrine parameters. Pre- and post-treatment data for each parameter were analyzed and compared. While most hematological parameters remained stable, significant alterations were observed in reticulocyte and platelet counts, as well as hemoglobin levels. Blood biochemistry exhibited greater variability, with notable changes in plasma proteins, bilirubin, uric acid, creatine kinase, creatinine, liver enzymes, and iron-binding capacity. No significant changes were observed in cortisol or thyroxine levels. According to our exploratory data, whole-body PEMF therapy showed no detectable adverse effects over five days on health or stress response. While most parameters remained unchanged, significant biochemical and hematological changes suggest that PEMF may support the animals and warrant further research on its mechanisms and applications.