Evaluation of cephalexin intermittent therapy (weekend therapy) in the control of recurrent idiopathic pyoderma in dogs: a randomized, double‐blinded, placebo‐controlled study

Abstract

The purpose of this study was to evaluate the efficacy of cephalexin intermittent therapy 2 days a week (weekend therapy) in the prevention of relapses of recurrent idiopathic superficial or deep pyoderma in dogs. Twenty‐eight dogs were entered into the study. A diagnosis of chronic idiopathic pyoderma was made based on: (1) history, including at least two previous relapses cured in the 12 months before inclusion; (2) clinical signs of pyoderma without underlying skin disease based on clinical presentation; and (3) appropriate diagnostic tests (compatible cytological examination and bacterial culture). In phase 1 of the study, dogs were treated with cephalexin (15 mg/kg twice daily) if sensitivity testing was compatible until 2 weeks after cure, for a minimum of 4 weeks and a maximum of 2 and 4 months for superficial and deep pyoderma, respectively. In phase 2, the cured dogs were then randomly and blindly allocated into two groups: Group 1 received cephalexin (15 mg/kg twice daily) on Saturdays and Sundays for 1 year, and Group 2 received a placebo in the same way. Dogs were examined every 3–4 weeks during phase 1 and every 2 months during phase 2, except in case of relapse justifying an earlier examination. Clinical signs of pyoderma were scored at each examination (11 parameters scored 0–3). No other systemic antibacterial or anti‐inflammatory treatments nor topical antibacterial or anti‐inflammatory treatments were permitted during both phases. The two groups were compared using Fischer's exact test for sex and clinical signs, and the Wilcoxon Rank‐Sum test for age, weight, number of relapses before inclusion, and duration of treatment in phase 1. The number of dogs remaining free of relapse, i.e. free of any pyoderma lesion, was compared between the two groups using a survival analysis with the Log‐Rank Test. The average time before relapse was compared between the two groups using the Wilcoxon Rank‐Sum test. In phase 1, one case was lost to follow‐up; two cases were excluded due to treatment failure and an additional two cases because of resistance in vitro to cephalexin. Various species of staphylococci sensitive to cephalexin were isolated in the 23 remaining dogs. In phase 2, 13 dogs received placebo and 10 received cephalexin. The two groups were not statistically different according to clinical signs (six cases of folliculitis in each group, three and five cases of furunculosis, one and two cases of cellulitis in Groups 1 and 2, respectively), sex, age, weight, number of previous relapses, and duration of treatment in phase 1. There was a significant difference between the two groups in the number of dogs that did not relapse. Two dogs in Group 1 did not relapse. Further, the rate of relapse over time was more rapid in the dogs receiving placebo. The average time until relapse in Groups 1 (6.6 months) compared to Group 2 (2.5 months) was significantly different. Resistance to cephalexin did not increase during the study. We conclude that cephalexin weekend therapy can be beneficial in dogs with idiopathic recurrent pyoderma. Funding: Virbac SA.