Correlation between leukocytosis and necropsy findings in dogs with immune-mediated hemolytic anemia: 34 cases (1994-1999)

Objective-To determine whether severity of leukocytosis correlates with sev erity of postmortem lesions in dogs with immune-mediated hemolytic anemia ( IMHA). Design-Retrospective study. Animals-34 dogs with IMHA that had CBC performed within 48 hours prior to d eath and complete necropsy examinations. Procedure-Dogs were independently assigned to 4 leukocytosis groups (within reference range; mild leukocytosis, moderate leukocytosis, marked leukocyt osis) and 3 lesion severity groups (mild lesions, moderate lesions, severe lesions). Results-Moderate to marked leukocytosis correlated with moderate to severe postmortem lesions. Ischemic necrosis within liver, kidney, heart, lung, an d spleen attributable to thromboembolic disease or anemic hypoxia were the most common important lesions found at necropsy. None of the dogs with mild lesions had moderate or marked leukocytosis. Four of 14 severely affected dogs had WBC counts within reference range, but all 4 had neutrophilic left shifts. Three of these 4 dogs had toxic change in neutrophils. Conclusion and Clinical Relevance-Moderate to marked leukocytosis, neutroph ilic left shift, and toxic change in neutrophils in dogs with IMHA should a lert clinicians to the potential for moderate to severe tissue injury, whic h could complicate treatment and worsen prognosis. Lesions appear to be sec ondary to anemic hypoxia, thromboembolic disease, or both; therefore, treat ment objectives should focus on improving blood oxygen-carrying capacity an d monitoring for thromboembolic disease.