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 parameters, 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.