This retrospective study aimed to identify potential systemic inflammatory markers within the parameters of the different cell types measured on a CBC. In humans, the neutrophil:lymphocyte ratio (NLR), platelet:lymphocyte ratio (PLR), mean platelet volume:platelet ratio (MPV/PLT), and platelet large cell ratio index (PLCRi) have been identified as biomarkers of systemic inflammatory response and potentially as prognostic/diagnostic biomarkers in both inflammatory and neoplastic conditions, including those of the head and neck region.
Neutrophils are the first leukocytes to circulate in response to systemic inflammation, and lymphopenia has been accepted as a negative prognostic indicator in humans with some types of cancer. A high NLR, another negative biomarker in human cancer patients, demonstrates an enhanced neutrophil response and relative lymphopenia. Platelets play a role in biologic progression and metastatic spread of tumors; PLR, MPV/PLT, and PLCRi are all biomarkers of platelet activation. The potential value of these indices in companion animals has yet to be determined.
Three populations of dogs were evaluated in this study: healthy dogs, dogs with periodontal disease, and dogs with oral tumors. The results ultimately were not supportive of systemic inflammatory response assessment by CBC indices in dogs with periodontal disease. However, 2 indices (ie, NLR and PLCRi) were associated with oral neoplastic conditions and could potentially be used as biomarkers of systemic inflammatory response if given further investigation.