Biochemical profile of the Pêga donkey (Equus asinus) breed: influence of age and sex

Inappropriate reference limits increase the risks of unnecessary investigations and diagnostic failures. Species, breed, environment, handling, and physiologic stage can influence serum biochemical variables. This study aimed to establish serum biochemical reference intervals of Pêga donkeys and the influence of age and sex on these variables. Samples were taken from 110 donkeys (79 females and 31 males; 8 under 1 year, 33 between 1 and 3 years, and 69 over 3 years old). There were no differences for creatine kinase (CK), albumin, urea, and magnesium among age groups. Animals under 1 year old had the lowest aspartate aminotransferase (AST), creatinine, triglycerides, total calcium, and chloride means; lower indirect bilirubin, gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), and sodium levels than over 3-year-old group and the highest phosphorus, glucose, cholesterol, ionized calcium, and alkaline phosphatase (AP) values. Total protein increased with age. The group from 1 to 3 years had higher potassium than up to 1-year-old group. Animals over 3 years old had the highest means of direct and total bilirubin. ALT, CK, GGT, direct and total bilirubin, urea, triglycerides, sodium, potassium, and chloride levels did not differ between genders. Females had higher AST, total protein, total calcium, and indirect bilirubin levels. Males showed greater AP, albumin, phosphorus, glucose, creatinine, cholesterol, magnesium, and ionized calcium values. Discrepancies among present results and previous studies show influencing factors on biochemical profile of donkeys and reinforce the importance of establishment of specific reference intervals. This study is useful in clinical routine and as basis to other scientific researches with Pêga donkeys.