Hematological reference intervals in newborn dromedary calves in the first week after birth: Age and sex-related variations

The establishment of hematological reference intervals (RIs) is an important tool to assess the health status of animals and to evaluate the impact of diseases at individual and population levels. Nowadays, specific RIs of hematological parameters in newborn dromedary camel calves at birth and during the first week after birth, are lacking. Therefore, RIs for the hematological variables from a complete blood cell count were established in 47 healthy newborn dromedary calves (18 females and 29 males). Blood samples were collected within 2 h after birth (d0), at 24 h (d1), at 3 (d3) and 7 days (d7) after birth, and analyzed within 24 h. The RIs were described based on the 95% confidence interval, and possible differences among mean values due to age (sampling time) and sex were investigated. Statistical analysis showed that age affected all the hematological variables except MCV, MCH, and MCHC, indicating that the adaptational process to the extrauterine life continues for several days after birth; sex affected most of the hematological variables, with higher RBC and PLT count, HGB, PCV, neutrophil population and neutrophil:lymphocyte ratio at d7 in females compared to males. These findings suggest possible sex-based differences in the physiological maturation mechanisms and deserves further investigations. To the best of the authors' knowledge, this is the first report of hematological RIs for newborn dromedary calves at birth up to 7 days of age; the RIs registered in the present study in newborns differ from those reported in adult dromedaries in literature, thus confirming the need for the adoption of separated reference ranges according to age also in the dromedary camel, as previously reported for other species.