Peripheral Lymphocyte Subsets as a Prognostic Indicator of Mortality and Morbidity in Healthy Dogs

Abstract

To evaluate the relationship among immune status and increased morbidity and mortality, peripheral blood lymphocytes (CD3⁺, CD4⁺, CD8⁺, CD21⁺ cells) from 32 healthy dogs aged over 8 years were analyzed. Twenty-five dogs out of 32 were followed-up for 3 years after the analysis, and 14 dogs were found to be diseased and nine dogs died. There was no notable difference between the age of dogs that died compared with the ones that survived. The relative percentage of CD4⁺ and CD4⁺:CD8⁺ ratio decreased notably in dogs falling ill compared with healthy dogs. The relative percentage of CD3⁺ lymphocytes showed a notable decrease in dogs that died within 3 years in comparison with dogs that survived. In a discriminant analysis of morbidity and mortality, most patients were correctly classified as diseased or not and surving or dead, respectively. These results indicate that the immunophenotypes of peripheral blood lymphocytes in older dogs offer promise as parameters for evaluating mortality and morbidity.