EXPERIMENTAL RESEARCH STUDIES
Comparison of glycopyrrolate and atropine in ameliorating the adverse effects of imidocarb dipropionate in horses
Reasons for performing study
Imidocarb, an effective treatment for piroplasmosis, may cause colic and diarrhoea in horses. Atropine and glycopyrrolate are anticholinergics that could reduce the adverse effects of imidocarb. However, atropine and glycopyrrolate inhibit gastrointestinal motility, potentially causing ileus and colic.
To compare glycopyrrolate and atropine in ameliorating the adverse effects of imidocarb dipropionate in horses and to determine the effect of combinations of these drugs on the gastrointestinal tract.
A blinded, randomised, crossover study was performed in 8 healthy horses. Each horse received 0.9% saline i.m and i.v. (CON), and imidocarb 2.4 mg/kg bwt i.m. with one of 3 treatments i.v.: 0.9% saline (IMI), atropine 0.02 mg/kg bwt (IMATROP) and glycopyrrolate 0.0025 mg/kg bwt (IMGLYCO). Clinical data, gastrointestinal motility via borborygmi and frequency of contractions in the duodenum, caecum and right dorsal colon assessed with transabdominal ultrasound, and faecal data were measured.
After imidocarb/saline treatment colic and diarrhoea were noted in 3 and 4 horses, respectively, faecal production and defaecation were increased for 3 h and faecal water percentage for 6 h. Colic was noted after atropine treatment in 4 horses, borborygmi and frequency of right dorsal colon contractions were significantly decreased for 2 h 15 min, and faecal production was not significantly different from CON. After glycopyrrolate treatment, colic was seen in one horse, frequency of intestinal contractions and faecal data were not significantly different from CON, and borborygmi was significantly decreased from CON at 1 h 15 min.
Results of this study suggest that glycopyrrolate is superior to atropine in ameliorating the adverse effects of imidocarb.
Glycopyrrolate could be administered with imidocarb in horses with piroplasmosis to reduce the adverse effects of imidocarb.