Hematological Parameters in Sheep: Variability, Determinants, and Applications in Flock Health Management

Blood is a key component of organisms, serving numerous functions, including metabolism, innate and humoral responses, and hemostasis. Variations in hematological parameters can indicate the presence of infectious and non-infectious diseases, chronic stress, and other pathological or physiological conditions. Complete blood count testing is common in human and veterinary medicine and, when combined with clinical examination, contributes to disease diagnosis and prognosis and the monitoring of therapeutic progression. Nevertheless, hematological analysis is not routinely performed in sheep due to the lack of case-specific reference intervals, complicating the interpretation of the results. Indeed, hematological parameters may be affected by various non-pathological (environmental, genetic, physiological) and pathological factors, and they require further understanding and relevant adjustments to be universally applicable. Therefore, the objective of this paper is to summarize the existing literature and describe how various pathological and non-pathological factors affect hematological parameters in sheep, thereby supporting their incorporation into health management practices.