This was a preliminary investigation of the use of lithium to prevent lomustine-induced myelosuppression. Four 10 to 11 kg beagles received lomustine 20 to 30 mg, PO, q3wk, with cephalexin prophylaxis. Two dogs also received lithium, 150 to 300 mg, PO, q12h. Lithium blood concentrations fluctuated in and out of therapeutic interval. Lithium was discontinued in one dog in week 13, and in the other dog in week 38, due to toxicoses. All dogs developed grade 1 to 4 neutropenia after each lomustine treatment. In dogs receiving lomustine only, platelet concentrations decreased from 274 and 293 × 10(9)/L in week 1, to 178 and 218 × 10(9)/L in weeks 38 and 13, respectively. In dogs receiving lomustine and lithium, platelet concentrations decreased from 351 and 288 × 10(9)/L in week 1, to 214 and 212 × 10(9)/L, in weeks 36 and 13, respectively. Lithium did not prevent lomustine-induced myelosuppression and had important side-effects.

Antimicrobial susceptibilities and toxin types were determined for 275 Clostridium perfringens isolates collected in Ontario in the spring of 2005. Minimal inhibitory concentrations (MICs) of C. perfringens isolates for 12 antimicrobials used in therapy, prophylaxis, and/or growth promotion of cattle (n = 40), swine (n = 75), turkeys (n = 50), and chickens (n = 100) were determined using the microbroth dilution method. Statistical analyses and MIC distributions showed reduced susceptibility to bacitracin, clindamycin, erythromycin, florfenicol, and tetracycline for some isolates. Reduced susceptibility to bacitracin was identified in chicken (64%) and turkey (60%) isolates. Swine isolates had predominantly reduced susceptibility to clindamycin (28%) and erythromycin (31%), whereas bovine isolates had reduced susceptibility to clindamycin (10%) and florfenicol (10%). Reduced susceptibility to tetracycline was spread across all species. No clear reduced susceptibility, but elevated MIC50 for virginiamycin was found in chicken isolates in comparison with isolates from other species. Toxin typing revealed that C. perfringens type A is the dominant toxin type isolated in this study across all 4 host species.