Reference intervals for bone marrow cells in juvenile and young adult cats bone marrow cytology

Background: The current bone marrow (BM) reference intervals (RI) are based on a limited number of cats. Age-related changes in BM variables might be important,possibly affecting the interpretation of the results.

Objectives: Establish BM cytologic reference intervals (RIs) and association of age and sex on these findings, in healthy juvenile and young adult cats.

Methods: BM aspirates of cats deemed healthy based on history and clinical, CBC, serum chemistry findings, and negative retrovirus serology were obtained and examined cytologically. The examination included a 1000-nucleated differential cell count and cell morphologic assessment. RIs were calculated using parametric, robust, and nonparametric methods. The cytologic findings were examined for associations with sex and age.

Results: The study included 40 cats (females, 22 [55%]; males, 18 [45%]) with a median age of 1.5 years (range 0.5-5). Most calculated RIs were similar to those previously reported. BM plasma cell and monocyte counts were weakly and positively correlated with age (r_s, .312 and .373, respectively; P < .05). Metarubricytes were higher infemales (mean, 25.1%; SD, 6.0%) than males (mean, 21.2%; SD, 6.0%; P < .05).

Conclusions: The BM differential cell counts determined in this study can serve as RIs for cats aged 0.5-5 years.