Pentoxifylline in canine dermatology (Proceedings)

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.

Table 1. Dermatologic Conditions in Dogs that May Respond to PTX

PTX is a methylxanthine derivative with hemorrheologic and immunomodulatory properties (Table 2). The major mechanism of action of PTX is believed to be nonselective phosphodiesterase inhibition. PTX typically has a slow onset of action in dermatological disorders: from 4 weeks in atopic and contact dermatitis, to up to 3 months in familial dermatomyositis and vasculitides. PTX is contraindicated with significant renal or hepatic disease or bleeding disorders. Fetal abnormalities were produced when PTX was given to pregnant rodents.

Table 2. Some Effects of PTX

In dogs, treatment protocols prior to 2000 were totally empirical and anecdotal. Currently, we are using 25 mg/kg, q12h, PO with food. Side effects are rare and include nausea, vomiting, and diarrhea. Anecdotal side effects include thrombocytopenia, erythema multiforme, bone marrow suppression, and flushing.

PTX appears to be a useful therapeutic option in atopic dermatitis, allergic contact dermatitis,familial dermatomyositis, lupoid onychitis, and various vasculitides. PTX seems to be of little or no benefit in vesicular cutaneous lupus erythematosus and exfoliative cutaneous lupus erythematosus.

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