Influence of age and season on blood biochemical parameters of free-roaming Karakachan horses

The present study investigated the influence of age and season on blood biochemical parameters in free-living Karakachan horses in Bulgaria. The study included 53 healthy mares divided into two age groups (young: 6 months to 3 years of age; adult: 3–10 years of age) which were followed during three seasons (spring, summer, autumn). Key blood biochemical parameters e.g. electrolytes, enzymes, proteins, and other biochemical markers were assayed using a BS-120 automatic biochemical analyzer (Mindray, China). The results showed significant differences in blood phosphorus (P<0.05) between age groups reflecting characteristic physiological and biochemical changes of different age. Seasonal variations influenced significantly blood parame-ters, with the most pronounced changes observed in blood minerals and enzyme activities. The concentrations of calcium, sodium, iron, magnesium, and potassium showed highly significant differences (P<0.001 to P<0.05) across seasons. Liver enzymes (alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase) and other biochemical markers (triglycerides, lactate dehydrogenase, creatinine) also varied significantly indicating potential adaptive physiological responses. The obtained reference values of blood indicators can serve as a basis for monitoring the health of Karakachan horses and assist veterinary specialists in timely diagnosis and treatment, as well as in the preservation of this unique breed.