A randomized controlled field trial of a novel trimethoprim-sulfadiazine oral suspension for treatment of Streptococcus equi subsp zooepidemicus infection of the lower respiratory tract in horses

• Autores: Scott R. McClure, Peggy Anne Hawkins, Robbin L. Koenig
• Localización: JAVMA: Journal of the American Veterinary Medical Association, ISSN-e 0003-1488, Vol. 246, Nº. 12, 2015, págs. 1345-1353
• Idioma: inglés
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• Resumen

  • Objective—To evaluate the effectiveness of a novel trimethoprim-sulfadiazine oral suspension for the treatment of naturally acquired Streptococcus equi subsp zooepidemicus infection in horses.

    Design—Randomized, controlled field trial.

    Animals—180 horses with S equi subsp zooepidemicus infection.

    Procedures—Horses with lower respiratory tract infections caused by S equi subsp zooepidemicus were treated with a new formulation of combined trimethoprim-sulfadiazine oral suspension at a dosage of 24 mg/kg (10.9 mg/lb) twice daily for 10 days (treatment group) or with an equivalent volume of saline (0.9% NaCl) solution (placebo group). Response to treatment, including clinical signs and fecal consistency scores, was assessed twice daily. Any adverse effects were recorded. The primary outcome variable was clinical response; the secondary outcome variable was eradication of S equi subsp zooepidemicus on study day 17 as determined by bacteriologic culture of repeated transtracheal-wash specimens.

    Results—Of the 119 horses allocated to the treatment group, 69 (58%) had a positive clinical response. A significantly smaller proportion of horses in the placebo group (9/61 [15%]) had a positive clinical response. By day 5, 25 of 61 (41%) placebo horses had been withdrawn from the study because of negative clinical response, compared with only 10 of 119 (8.4%) treated horses. By day 10, 28 of 61 (46%) placebo horses had been withdrawn because of negative clinical response, compared with only 13 of 119 (11%) treated horses. There were few adverse events associated with the trimethoprim-sulfadiazine suspension. There were no significant differences in fecal consistency scores between treatment and placebo groups.

    Conclusions and Clinical Relevance—The new oral suspension administered at 24 mg/kg twice daily effectively treated the clinical signs of S equi subsp zooepidemicus lower respiratory infection in horses and eliminated the organism from the respiratory tract. Adverse effects were minimal.