Hypocalcemia, or low blood calcium, is a significant metabolic disorder in dairy cattle, manifesting as clinical (milk fever) or subclinical forms. Clinical hypocalcemia presents as a recumbent cow shortly after calving, while subclinical hypocalcemia shows low blood calcium levels without clinical signs. The incidence of clinical hypocalcemia varies greatly (0–83%), influenced by factors like cow comfort and nutritional management. Subclinical hypocalcemia affects 25–50% of early-lactation multiparous cows. A recent approach uses “calciumdynamics” (Ca changes over the first few days post-partum) to better classify the disease, categorizing cows into four groups. Dyscalcemic cows, including persistently or delayed hypocalcemic cows, experience reduced dry matter intake, an increased risk of early lactation disease, and lower milk yield. Hypocalcemia etiopathogenesis involves a sudden increase in calcium excretion to support colostrum and milk production. This strains calcium homeostasis, leading to a decrease in blood calcium, particularly around calving. Clinical hypocalcemia progresses through three stages, from hyperexcitability to recumbency and potentially death if untreated. Subclinical hypocalcemia lacks clinical signs, requiring blood tests for diagnosis. Diagnosis involves history, physical examination, and response to treatment. The treatment for clinical hypocalcemia typically involves intravenous administration of calcium borogluconate, followed by oral calcium supplements to prevent rebound hypocalcemia. Treatment for subclinical hypocalcemia focuses on prevention strategies, primarily through dietary management. These include reducing the dietary cation-anion difference (DCAD) and potentially using Ca-binders. Additional preventative measures emphasize optimal cow comfort.