Abstract:Background: Reticulocyte hemoglobin content provided by the Siemens ADVIA (CHr) is an established marker of iron deficiency. The IDEXX ProCyte Dx hematology analyzer now provides a similar variable, reticulocyte hemoglobin equivalent (RET-He). Objectives: The objective was to evaluate RET-He and its diagnostic utility in dogs, and to calculate a cutoff value for diagnosing iron-deficient erythropoiesis (IDE). Furthermore, the prevalence of RET-He values below this cutoff value was established. Methods: One hundred and seventy-one CBCs of healthy dogs were used to establish a RI. Stability of RET-He was evaluated by repeated measurements over 48 hours (n = 10). The 25-run coefficient of variation (CV) was calculated, and correlation and bias between measurements of RET-He and CHr were assessed (n = 190). A cutoff value for diagnosing IDE was calculated. The utility of RET-He in the detection of IDE was evaluated in 123 dogs. The prevalence of low RET-He values was assessed retrospectively in a multicenter study (2012)(2013)(2014) under participation of 7 veterinary clinics. Results: Reticulocyte hemoglobin equivalent with an RI of 22.2 to 28.6 pg was statistically stable over 48 hours (P = .10). The CV was 1.8%. A fair correlation (q = 0.74) between RET-He and CHr with a small bias of À0.6 pg was found. The cutoff value for diagnosing IDE was 20.9 pg (sensitivity: 85%; specificity: 99%).

Low RET-He values indicate IDE even in dogs with other CBC variables within the RIs.

In both species, reticulocytosis without anaemia was observed in a low proportion of blood samples (dogs>cat). Though a bias towards sick animals is possible in our sample, reticulocytosis without anaemia was mainly seen in diseased animals and associated with a mortality rate of approximately one-third of patients.