Determination of a reference interval for mast cells in peripheral lymph nodes of healthy dogs and comparison to dogs with inflammatory skin disease

Reference intervals for mast cell (MC) counts in popliteal lymph node (LN) aspirates of 30 healthy dogs were established by evaluating the total MCs counted in 20 fields, the total MCs/ 500 lymphoid cells, and the total MCs/ entire smear. MC counts from superficial cervical and popliteal LNs were determined in 20 dogs with allergic skin disease and compared to the counts from the healthy dogs. There were significantly more MCs in smears of LN aspirates of allergic dogs as compared to healthy dogs. Reference intervals based on counts from the total sample evaluated in healthy dogs was 0-13. Significantly more MCs were counted in the popliteal versus the superficial cervical LNs with the Total and Fields methods. Evaluating the MC counts of the entire smear found significantly more MC than other methods and is the preferred method to evaluate for the presence of MC in aspirates.