Age-associated changes in the immune system of German Shepherd dogs

In order to look into the ageing of the canine immune system we investigate d age-related changes and associated gender-related differences in paramete rs of innate and acquired immunity in German Shepherd dogs. We obtained the following findings: white blood cell counts, peripheral blood lymphocytes, lymphocyte proliferative activity and interleukin-2 (IL-2) serum concentra tions were significantly lower in the group of old animals, whereas the con centrations of gamma-globulins and the functional activity of the complemen t system were significantly higher in the elderly. Phagocytic and bacterici dal activity of polymorphonuclear cells, as well as their 'killing function ', the serum cytokine-like activities of tumour necrosis factor-ct and the plasma concentrations of immunoglobulin G, as well as of alpha- and beta-gl obulins, were not significantly affected by age, whereas natural killer-cel l activity and the serum cytokine-like activities of IL-1 were significantl y higher only in the group of female old animals. With regard to gender-rel ated differences, lymphocyte proliferative activities as well as plasma con centrations of alpha-globulin were significantly higher in the group of fem ale animals, whereas the absolute numbers of segmented neutrophils were sig nificantly lower. Species analogies with regard to ageing as presumed to ex ist between man and laboratory rodents also seem to be applicable to the do g. The observed age-related changes in the canine immune system are probabl y among the main causes for the multimorbidity of old age, affecting life e xpectancy and mortality in the dog and should be recognized and considered by the attending veterinarian.