Application of Immuno-Modulatory Effect of Histamine Antagonist in Chronic Recurrent Pyoderma of Dogs

In comparison to other mammalian species, dogs seem uniquely susceptible to both single-event pyoderma and recurrent pyoderma. The reasons for this phenomenon are not known, but may relate to various host factors that could result in enhanced susceptibility to infection. These factors could include the comparatively thin, compact stratum corneum of dogs, the relative lack of intercellular lipids in the canine stratum corneum, the lack of a lipid-squamous epithelial plug in the entrance of canine hair follicles, and the relatively high pH of canine skin. Successful management of all deep pyoderma requires systemic antibiotic therapy along with topical antibacterial shampoo therapy as an adjunct to speed recovery, improve patient well-being and attitude, encourage owners, and potentially prevent recurrence. The most common underlying conditions for chronic or recurrent canine pyoderma are atopic dermatitis, food allergy, flea allergy and hypothyroidism followed by hyperestrogenism, demodicosis and zinc responsive dermatosis. Atopic dogs are prone to recurrent skin infections due to increased adherence of staphylococcal bacteria to atopic canine skin cells, alterations in normal skin barrier function, and altered skin immune system function. Immunomodulatory therapy is used frequently in an attempt to prevent or diminish the frequency of recurrent superficial infection. Considerable evidence has emerged to suggest that histamine participates in the regulation of the inflammatory response, immune reaction and coagulation cascade. Specific histamine receptors have been identified on the surface of bone marrow cells, immune competent cells, endothelial cells, fibroblasts, and also on malignant cells. It is suggested that the histamine-2 receptor antagonists have potential beneficial effects in the treatment of certain malignant, autoimmune and skin diseases, either alone or in combination with other drugs. Present paper reports the clinical efficacy of ranitidine (histamine-2 receptor antagonist) in treatment of chronic recurrent pyoderma. For the purpose, based on chronic recurrent nature of pyoderma, twelve dogs of either sex or breed were selected for comparative efficacy of ranitidine (all of them were previously treated with many antibiotics, glucocorticoids and various topical therapies). Average age of dogs was 5–7 years, theses 12 dogs were randomly divided in two groups. Group I was treated with cephelexin (30 mg·kg-1 p.o. q 24 h) along with shampoo therapy (having 2% chlorhexidine gluconate, 2% ketoconazole and 0.1% cetrimide) once weekly basis. Dogs of group second were given additional treatment of ranitidine (mg·kg-1 p.o. q 12 h). After therapy period of 30 days the dogs of both were evaluated clinically, 4dogs of the group I and 5 dog of group II were responded for the treatment. Follow up was done with advice of shampoo therapy in group I and shampoo therapy with ranitidine in group II, revaluation was done and recurrence was noticed in 3 dogs of group I but none of the case of group II recurred.