The tetracyclines were initially used as bacteriostatic antibiotics. Niacinamide (the amide of niacin) is a vasodilator. These agents also have some interesting in vitro and in vivo anti-inflammatory and immunomodulatory properties.

Pentoxifylline (PTX) has been heralded as "the drug of the decade" and "a wonder drug". There is variably believable information (anecdotal-to-scientific) suggesting the therapeutic efficacy of PTX in a staggering number of dermatoses in human and veterinary (Table 1) medicine.PTX has been reported to have a steroid-sparing effect.

Malassezia yeasts and Malassezia dermatitis have been the subject of almost innumerable publications and anecdotes since the early 1990s. The condition is diagnosed commonly in the dog and uncommonly in the cat.

Erythema multiforme was first documented in the dog in 1983 and in the cat in 1984.

Pruritus and the various aberrations of skin and hair coat that it provokes are, by far, the most common reasons for which cats are presented to veterinarians for dermatologic diagnosis.

Cutaneous vasculitis was first documented in a dog in 1980. Vasculitides can be apparently limited to the skin or, less commonly, the skin may be one of multiple organ systems involved.