After a decade of use in small animals, studies and clinical experiences have shown that the family of fluoroquinolone antibiotics can be valuable in the treatment of infections in horses though there are some caveats. This includes the well known antibiotic Baytril (enrofloxacin) which is given by injection or orallyand the less well known members of this group that can be given orally. This article contains information about the use, contraindications, toxic effects, and dosages of these antibiotics.

Enrofloxacin is available and can be administered by the oral, IV, or IM routes. These antibiotics have a wide spectrum of activity but does not include Streptococcus or anerobes. It is marginally active against P. aeruginosa may require doses that have not been tested for safety in horses. That makes this class of drugs important in battling staph or gram negative bacteria where other choices like the aminoglycosides are contraindicated. Because it does not upset anaerobes it may cause less disruption to the bacteria in the GI tract.

The pharmacokinetics of difloxacin and its distribution within the body fluids and endometrium of 6 mares were studied after intragastric (IG) administration of 5 individual doses. All isolates of Salmonella spp. and Pasteurella spp. were susceptible and, in general, gram-negative organisms were more susceptible than gram-positives. Difloxacin appears to be safe, adequately absorbed, and well distributed to body fluids and endometrial tissues of mares and may be useful in the treatment of susceptible bacterial infections in adult horses.