<p>Tick-borne hemoparasitic infections are endemic in northern India, and the warm southwest-central region of Punjab provides favorable conditions for tick proliferation, potentially increasing the risk of bovine theileriosis. This communication aimed to investigate high-density <i>Theileria</i> spp. parasitism using gold-standard, i.e., Giemsa-stained thin blood smear examination, and to quantify associated Haemato-biochemical in clinical positive cases from Bathinda district, Punjab (India). Animals were grouped as <i>Theileria-</i>positive (<i>n</i> = 35) and smear-negative healthy controls (<i>n</i> = 29). Clinically, infected animals showed anorexia, lethargy, fever, lymphadenopathy, and tick infestation; grossly, lymphadenomegaly and pale ocular/vulvar mucosa were prominent. Compared with controls, infection was associated with marked anemia and leukogram shifts (haemoglobin, total erythrocyte count, packed cell volume, lymphocyte, neutrophil, etc.). Biochemically, Serum Glutamic-Oxaloacetic Transaminase (SGOT) and Lactate Dehydrogenase (LDH) increased, total protein and calcium decreased, and Serum Glutamic Pyruvic Transaminase (SGPT), creatinine, phosphorus, and glucose were also changed, but at not-significant level. High-density <i>Theileria</i> spp. parasitism in this endemic setting is linked to clinically evident disease with substantial Haemato-biochemical derangements, supporting the use of integrated clinical assessment and hemato-biochemical profiling to inform diagnosis and therapeutic decision-making.</p>