The in vitro proliferative responses of peripheral blood mononuclear cells from seven healthy basset hounds exposed to Malassezia pachydermatis antigen (500 micrograms/ml) exceeded (P < 0.05) those of seborrhoeic basset hounds with high populations of M pachydermatis and eight Irish setters with gluten-sensitive enteropathy. The stimulation indices in the latter two groups and in eight healthy beagles were comparable. The stimulation indices of the four groups after exposure to phytohaemaglutinin did not differ significantly. The serum titres of M pachydermatis-specific IgG and IgA measured by enzyme-linked immunosorbent assays (ELISA) in 21 seborrhoeic basset hounds and 11 affected dogs of various breeds exceeded those of 14 healthy basset hounds and eight healthy beagles (P < 0.01 for IgG, P < 0.05 for IgA). Total serum IgA concentrations measured by ELISA in the affected dogs were not lower than those of healthy dogs.

The concentration of immunoglobulins in faecal extracts was investigated as a method of assessing the production of immunoglobulins by the gut mucosa of 137 dogs. There were significant correlations between the concentrations in faecal extracts and the concentrations produced in duodenal organ cultures. Seventy-six German shepherd dogs had significantly lower median immunoglobulin A (IgA) concentrations in their faecal extracts than 63 controls of various breeds. Sixteen of the German shepherd dogs had IgA concentrations below the 95 per cent confidence limit of the control population and six had no demonstrable faecal IgA. The faecal concentrations of immunoglobulin G and albumin were significantly higher in the German shepherd dogs than in the controls, but their immunoglobulin M concentrations were similar.

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