RESUMO
Canine urinary excretion of chloramphenicol was evaluated to optimize a dosing protocol for treating urinary tract infections. Seven healthy male intact purpose-bred Beagles and six healthy client-owned dogs of various breeds each received a single oral 50 mg/kg dose of chloramphenicol. Urine was collected at baseline, and 6, 8, 12, and 24 h after chloramphenicol. Chloramphenicol urine concentrations were measured and compared to the epidemiological cutoff value for E. coli (16 mcg/mL). At 8 h, mean chloramphenicol concentration from all dogs was 266.9 mcg/mL (90% CI 136.2-397.7 mcg/mL) but was lower in Beagles than client-owned dogs. At 12 h, mean chloramphenicol concentration from all dogs was 111.0 mcg/mL (90% CI 36.9-185.0 mcg/mL) and was lower in Beagles (10.6 mcg/mL, 90% CI 1.4-19.8 mcg/mL) than client-owned dogs (228.0 mcg/mL, 90% CI 103.0-353.1 mcg/mL). Urine half-life was similar for all dogs (1.8-3.8 h). This justifies dosing chloramphenicol 50 mg/kg PO q 8 h. All client-owned dogs additionally maintained concentrations well above 16 mcg/mL, for 12 h, suggesting that q 12-h dosing might be appropriate for non-Beagle dogs with susceptible lower urinary tract infections. A clinical trial in dogs with urinary tract infections is needed as well as further investigation into potential breed differences.
RESUMO
The canine urinary excretion of florfenicol was evaluated to explore its potential for treating urinary tract infections. Nine healthy male intact purpose-bred Beagles and four healthy client-owned dogs each received a single oral dose of florfenicol 20 mg/kg (300 mg/mL parenteral solution) with food. All voluntary urinations were collected for 12 h. Although florfenicol is reportedly bitter tasting, 7/9 Beagles and 4/4 client-owned dogs completely ingested the florfenicol and were enrolled; salivation (n = 1) and headshaking (n = 3) were observed. The last measured urine florfenicol concentrations were variable: Beagles (0.23-3.19 mcg/mL), Pug (3.01 mcg/mL) English Setter (21.29 mcg/mL), Greyhound (32.68 mcg/mL), and Standard Poodle (13.00 mcg/mL). Urine half-life was similar for the Beagles and the Pug, 0.75-1.39 h, whereas the half-life was 1.70-1.82 h for the English Setter, Greyhound, and Standard Poodle. Larger breed dogs exceeded 8 mcg/mL florfenicol (wild-type cutoff) in their urine at 12 h, whereas the Beagles and Pug had <8 mcg/mL; it is unclear if this is an individual, breed, or size difference. These data suggest oral florfenicol may need to be administered q6-12h for canine urinary tract infections, but further data are needed (more enrolled dogs, multiple-dose regimens) before considering clinical trials or breed-specific differences.