Effect of sulfadiazine and pyrimethamine on selected physiologic and performance parameters in athletically conditioned thoroughbred horses during an incremental exercise stress test
Colahan, P.T.; Bailey, J.E.; Johnson, M.; Rice, B.L.; Chou, C-Chung.; Cheeks, J.P.; Jones, G.L.; Yang, M.
Veterinary Therapeutics Research in Applied Veterinary Medicine 3(1): 49-63
2002
ISSN/ISBN: 1528-3593 PMID: 12050828 Document Number: 547502
Following the regimen used to treat equine protozoal myeloencephalitis, sulfadiazine (20 mg/kg) and pyrimethamine (1 mg/kg) were administered orally once daily to 12 physically conditioned Thoroughbred horses for 4 consecutive days. The horses were randomly assigned to two test groups in a crossover design, with each horse serving as its own control. A stepwise exercise stress test was conducted to exhaustion. No effect on athletic performance was observed, and only marginal effects were noted in some haematologic and serochemical measurements, including decreased total white blood cell counts, red blood cell distribution width, total haemoglobin serum sodium, and serum chloride. Serum folic acid concentration decreased significantly following sulfadiazine/pyrimethamine treatment.