Patrick Hensel
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In veterinary dermatology, the need for more effective and convenient drugs with fewer side effects is continuous. Here are
some of the newer drugs available, as well as a few older preparations with new indications.
ANTIMICROBIALS
A variety of veterinary-approved antimicrobials are available to treat pyodermas in small-animals. To minimize the development
of antibiotic-resistant microorganisms, it is strongly recommended to use only veterinary-approved antibiotics. Beyond antimicrobial
selection, important reasons for treatment failure include inadequate antibiotic dosing or duration and lack of owner compliance.
Cephalexin is still a first-choice antibiotic for simple pyodermas, but under certain circumstances newer generations of cephalosporin
may be indicated. Treatment duration varies based on the severity of infection and should be continued until one to two weeks
beyond clinical resolution.
Cefovecin sodium
Cefovecin sodium (Convenia—Pfizer Animal Health) is a semisynthetic third-generation cephalosporin with a bactericidal effect.
It is indicated to treat skin infections caused by Staphylococcus species and Streptococcus canis in dogs and Pasteurella multocida in cats. Occasionally, gastrointestinal signs (diarrhea, vomiting) can be seen with the use of this drug.
Cefovecin is administered subcutaneously (8 mg/kg) and can be repeated in seven to 14 days, making it convenient for noncompliant
clients. However, care must be taken to ensure that the infection is completely cleared before stopping treatment. Even though
the convenience of this drug is tempting, it is not recommended for superficial pyodermas, which are likely to respond well
to cephalexin. Instead, it should be reserved for deeper infections.
Cefpodoxime proxetil
Another third-generation cephalosporin, cefpodoxime proxetil (Simplicef—Pfizer Animal Health), is also available for treating
skin infections in dogs. This drug is well-tolerated, although gastrointestinal signs may occasionally occur. It is administered
orally once a day (5 to 10 mg/kg), making it a convenient choice. And since it is provided as a tablet and not a gelatin capsule,
it is a good choice for dogs that are undergoing a hypoallergenic elimination diet trial to rule out cutaneous adverse food
reaction.
Chloramphenicol
One nearly forgotten antibiotic is chloramphenicol. Because contact with this drug can cause an irreversible aplastic anemia
in a small percentage of people, it is no longer routinely used in human medicine. Because of the rare use of chloramphenicol,
methicillin-resistant Staphylococcus species infections have often been susceptible to this drug so far. However, these infections are invariably secondary to
an underlying condition, so beyond treatment of the infection, the primary problem must be identified and addressed. Treatment
of methicillin-resistant Staphylococcus species should also always be based on a culture and sensitivity.
Chloramphenicol has good tissue penetration, but since it is bacteriostatic, appropriate dosing and duration of treatment
must be achieved. Drawbacks to its use are that it must be given orally (30 to 50 mg/kg) three times a day, and owners need
to be advised about the human health risks and wear gloves whenever handling the drug to avoid exposure.
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