Survey on basal blood plasma catecholamine concentrations in Martina Franca donkey (Equus asinus).

BACKGROUND: Catecholamines are among the most frequently investigated parameters for studying sympathoadrenal activity in response to stress conditions. OBJECTIVES: To evaluate basal plasma concentrations of catecholamines (adrenaline, noradrenaline and dopamine) in healthy donkeys. STUDY DESIGN: Cross-sectional study. METHODS: Catecholamine concentrations from 440 Martina Franca donkeys were determined: 269 females and 171 entire males, aged from 4 months to 24 years. Animals were subdivided into four age categories: under 12 months old (64 males and 54 females), from 13 to 36 months (56 males and 75 females), from 37 to 120 months (49 males and 80 females) and over 120 months (24 males and 38 females). Indwelling jugular catheters were inserted at least 12 h before drawing blood. The data set was subjected to analysis of variance considering age, sex and the two-way interaction between them as independent variables. Pearson's correlation coefficients between the three catecholamines were evaluated. RESULTS: Confidence intervals (CI) for noradrenaline concentration ranged between 239.98 and 255.07 ng/L (mean 247.52 ng/L), for adrenaline between 129.27 and 137.90 ng/L (mean 133.59 ng/L), dopamine concentrations between 149.62 and 160.80 ng/L (mean 155.21 ng/L) and noradrenaline/adrenaline ratio between 1.91 and 2.05 (mean 1.98). Catecholamine plasma concentrations were not influenced by sex. Donkeys older than 37 months had lower adrenaline and noradrenaline plasma concentrations (P<0.001) and higher noradrenaline/adrenaline ratios (P<0.01) than younger animals. MAIN LIMITATIONS: Indwelling catheters and blood drawing procedures may have influenced catecholamine levels. CONCLUSIONS: Catecholamine concentrations were established within a large group of healthy Martina Franca donkeys.