Abstract
The normal level of serum IgA in Western Australian dogs was defined by single radial immunodiffusion using sera from 100 healthy randomly selected adult crossbred animals. Serum IgA values of 185 animals from six breeds were also determined. The mean and variance of serum IgA of these groups were similar to the crossbred dogs with the exception of German shepherd dogs where these values were statistically greater. In addition, 210 dogs with a range of chronic diseases (autoimmune, hypersensitivity, pyoderma, neoplasia, demodecosis, disseminated aspergillosis) were assayed and low values recorded in five cases. In all disease groups the mean serum IgA value was significantly greater than in the crossbred group and the variance significantly greater in most of these groups. The German shepherd group were the only normal dogs with a mean and variance similar to those of the clinical series suggesting that this breed may have a primary defect in IgA metabolism.