Immune-mediated disease as a risk factor for canine lymphoma.

BACKGROUND. Autoimmune diseases and neoplasia have been associated as occurring simultaneously in individuals. This study evaluated the association between the simultaneous occurrence of canine lymphoma and various immune-mediated diseases. METHODS. The Veterinary Medical Data Program, a national disease data registry for veterinary schools, was examined. The following immune-mediated disease categories were evaluated: lupus disorders, pemphigus disorders, autoimmune polyarthritis, immune-mediated hemolytic anemia, and immune-mediated thrombocytopenia. Odds ratios with 99% confidence intervals were calculated for the occurrence of lymphoma and each of the immune-mediated disorder categories. RESULTS. Only dogs with immune-mediated thrombocytopenia had a statistically significantly increased odds ratio (5.61; 99% confidence interval, 4.16-7.57) for the occurrence of lymphoma versus the general population. This association still was observed for immune-mediated thrombocytopenia when stratified by age, sex, and neutering status. CONCLUSION. Dogs with immune-mediated thrombocytopenia had a greater occurrence of lymphoma than dogs without immune-mediated thrombocytopenia.