Research Updates: Single-injection antibiotic treatment for cats with abscesses and infected wounds

Cephalosporins are often used as first-line antibiotics for superficial skin infections in dogs and cats. However, subcutaneous abscesses in cats are more commonly treated with broader-spectrum second-line antibiotics such as amoxicillin-clavulanic acid despite results that suggest that penicillins may be ineffective in many cases.1

Erika Meler, DVM, MS

The purpose of this multicenter, randomized, double-blinded, controlled clinical study was to compare the efficacy of a new cephalosporin option (single subcutaneous injection of cefovecin) with that of a positive control cephalosporin (once-daily orally administered cefadroxil) for the treatment of abscesses and infected skin wounds in cats. In this study, 177 cats with moderate to severe cutaneous abscesses or infected wounds were included in the antimicrobial effectiveness analysis. Swabs of affected areas obtained at initial presentation were submitted for aerobic and anaerobic bacteriologic culture; a positive culture result of pathogenic bacteria was required for inclusion.

Barrak Pressler, DVM, PhD, DACVIM

Cats were randomly assigned on the day of admission to receive either a single dose of cefovecin (89 cats; 8 mg/kg subcutaneously), followed by owner administration of placebo drops for two weeks, or one subcutaneous placebo injection, followed by owner administration of cefadroxil (88 cats; 22 mg/kg orally every 24 hours) for two weeks. Concurrent wound management, including clipping and drainage of the abscess or surgical débridement of the skin wound but no concurrent topical antiseptic was allowed. Additional topical or systemic antibiotics or glucocorticoids were not permitted.

Cats with abscesses made up 71% of the study group, while those with infected wounds made up 27%. Pasteurella multocida was the most common pathogen recovered from culture specimens. Other pathogenic bacteria commonly isolated included Prevotella species, Streptococcus canis, coagulase-negative Staphylococcus species, Staphylococcus intermedius, Fusobacterium species, Escherichia coli, and Porphyromonas species.

After 14 days, 98% of the cats treated with cefovecin had resolution or significant improvement in skin infections vs. 95% of the cats treated with cefadroxil; no significant difference was seen in the efficacy of these two drug regimens. At the final assessment (28 days after diagnosis), 2% vs. 9% of the cefovecin- and cefadroxil-treated cats, respectively, were considered treatment failures. Cefovecin-associated side effects reported by owners were similar to those of other cephalosporins and were usually related to the gastrointestinal tract. Although no statistical analysis was performed, the number of cats with vomiting or diarrhea was higher in those administered cefadroxil (14 with vomiting and 26 with diarrhea) than in those receiving cefovecin (10 with vomiting and seven with diarrhea).

COMMENTARY

This study demonstrated that the use of a single dose of cefovecin at the manufacturer's recommended dosage was at least as effective as an alternative, commonly used cephalosporin. The study also validated the results of a previous European study comparing the use of cefovecin to amoxicillin-clavulanic acid for the same indications.2 In addition, the high cure and significant improvement rate reported here suggests that cephalosporins may be appropriate first-line antibiotics for cutaneous infections in cats. However, because of the recurring nature of subcutaneous abscesses in cats, longer-term follow-up is still required to ensure that this class of drugs is truly effective for disease resolution. In the European study, 95% of cats with subcutaneous abscesses treated with cefovecin required only one course of treatment vs. 81.5% of cats with infected skin wounds.2 Cefovecin may be particularly appealing in difficult-to-handle patients, those with owners who have difficulty administering pills, or outdoor cats that cannot be reliably given daily drugs.

Keep in mind that extrapolating the results of this study to justify using cefovecin to treat other infections at other sites is inappropriate at this time; whether cefovecin's minimum inhibitory concentration is achieved in other body tissues requires further study. However, the unchanged urinary excretion of this drug reported elsewhere suggests that it is a reasonable choice for treating urinary tract infection in some cats.3,4 Finally, a long-term evaluation of the consequences of subcutaneous injection of this long-acting drug is needed to ensure its safety, particularly because the factors associated with injection-site sarcomas are still unknown.

Six R, Cleaver DM, Lindeman CJ, et al. Effectiveness and safety of cefovecin sodium, an extended-spectrum injectable cephalosporin, in the treatment of cats with abscesses and infected wounds. J Am Vet Med Assoc 2009;234(1):81-87.

The information in "Research Updates" was provided by Erika Meler, DVM, MS, and Barrak Pressler, DVM, PhD, DACVIM, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907.

REFERENCES

1. Lilenbaum W, Nunes EL, Azeredo MA. Prevalence and antimicrobial susceptibility of staphylococci isolated from the skin surface of clinically normal cats. Lett Appl Microbiol 1998;27(4):224-228.

2. Stegemann MR, Sherington J, Passmore C. The efficacy and safety of cefovecin in the treatment of feline abscesses and infected wounds. J Small Anim Pract 2007;48(12):683-689.

3. Stegemann MR, Sherington J, Coati N, et al. Pharmacokinetics of cefovecin in cats. J Vet Pharmacol Ther 2006;29(6):513-524.

4. Passmore CA, Sherington J, Stegemann MR. Efficacy and safety of cefovecin for the treatment of urinary tract infections in cats. J Small Anim Pract 2008;49(6):295-301.