Association between skin surface pH, temperature and Staphylococcus pseudintermedius in dogs with immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis.

Secondary bacterial infection is a frequent complication in lesional skin of dogs with immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis (ImR-LPP). However, the influence of skin pH and temperature in determining the composition of the cutaneous microflora at lesional sites has not been investigated. The association between ImR-LPP and pedal skin temperature, pH and Staphylococcus pseudintermedius isolates was thus evaluated. Temperature and pH were measured in 20 dogs with ImR-LPP and in 30 clinically healthy control dogs, and S. pseudintermedius was cultured from interdigital and palmoplantar swabs in both groups and scored semi-quantitatively for bacterial growth. In the ImR-LPP group, mean skin pH was slightly, but significantly, higher at both interdigital and palmoplantar sites. Staphylococcus pseudintermedius was isolated more frequently, and scores for bacterial growth were also significantly higher. However, mean skin temperatures were not significantly different from those in the control group. The isolation of S. pseudintermedius was significantly associated with ImR-LPP, with the single exception of isolates on Columbia blood agar from the palmoplantar region. However, pH and temperature were not significantly associated with the disease, and were not associated with the isolation of S. pseudintermedius at most sites sampled. Staphylococcus pseudintermedius was not isolated from all feet sampled in dogs with ImR-LPP. Taken together, these data would suggest that S. pseudintermedius infection is most likely to be a secondary phenomenon in dogs with ImR-LPP, and that changes in skin pH and temperature are not significant risk factors for this disease.

Clinical, immunological and histopathological findings in a subpopulation of dogs with pododermatitis.

Clinical, immunological and histopathological findings in 20 adult dogs of varying breeds with chronic (>or=6 months) inflammation confined to the pedal skin were compared over a 2-year period with those of a group of age-matched controls (n=20). All affected dogs were pruritic but systemically well. Lesions were present on all four feet in 18/20 cases. Affected feet were characteristically erythematous, swollen, painful and alopecic. Sinus tracts were evident in 4/20 dogs. Despite a methodical series of diagnostic tests, no underlying cause was identified. None of the dogs responded to antimicrobial therapy administered for 8 weeks, none had evidence of ectoparasitism and none satisfied the criteria for atopic dermatitis. There was no response to a dietary trial using a novel protein source. The condition was characterized histopathologically by epidermal hyperplasia, hyperkeratosis, spongiosis, dermal oedema and perivascular aggregates of lymphocytes and plasma cells. Clinical signs did not correlate with histopathological findings. Affected dogs had significantly elevated serum IgG and IgM concentrations. The results of lymphocyte proliferation assays and phenotypic studies to determine the relative percentage of CD3+, CD4+, CD8+ and CD21+ lymphocyte subsets, and the ratio of CD4+/CD8+ cells were not significantly different between groups. No age, sex or seasonal predilections were noted. All dogs subsequently responded to immunosuppressive doses of prednisolone or cyclosporin. The term immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis is proposed to denote what may be a previously unrecognized condition in some dogs with pododermatitis of undetermined aetiology.