EFFECTS OF 2 LARGE DOSES OF EQUINE RECOMBINANT GROWTH-HORMONE ON CLINICAL, HEMATOLOGICAL AND SERUM BIOCHEMICAL VARIABLES IN ADULT HORSES

Objective To evaluate the clinical, haematological, and serum biochemi cal effects of two large doses of recombinant equine growth hormone. D esign Duplicated Latin square. Sample population Three Thoroughbred an d three Standardbred mares aged between 12 and 17 years. Procedure Two horses were randomly assigned into one of three groups. On each of th ree successive days, each horse pair received one of two dosages of gr owth hormone or a saline placebo so that by the end of the experiment all three horse pairs had received both dosages and the saline placebo . Dose rates selected were 50 mu g/kg, and 100 mu g/kg. A clinical exa mination was performed and a venous blood sample drawn for a complete blood count and serum biochemical analysis before administration of gr owth hormone and at 1, 2, 3, 4, 6, 8 and 24 h after injection. Data we re analysed by a repeated measures analysis of variance assessing the effects of dose and time. Results There was an effect of time on a num ber of clinical, haematological, and serum biochemical variables. Ther e were significant effects of growth hormone on heart rate and serum g lucose concentration but values for both variables remained within the reference range. Conclusion The results of the present study suggest that equine recombinant growth hormone has a wide margin of safety and show that the single administration of up to five times the recommend ed dose rate has no significant effects on clinical, haematological, o r serum biochemical variables.