Size Matters: Zoo Data Analysis Shows that the White Blood Cell Ratio Differs between Large and Small Felids.

Sergey V Naidenko,Mikhail V Alshinetskiy

doi:10.3390/ani10060940

Sergey V Naidenko, Mikhail V Alshinetskiy

Open Access

https://doi.org/10.3390/ani10060940

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Abstract

The total number of white blood cells (WBCs) is related the immune system. In mammals, it is affected by the body mass, but it is unclear how the numbers of different WBC types correlate with this parameter. We analyzed the effect of body mass on WBC number and ratio in felids, where species are similar in diet (warm-blood vertebrates) and reproductive strategy (promiscuity). Based on zoo veterinary data (ZIMS database) we analyzed the effect of body mass on WBC number and neutrophils/lymphocytes ratio in 26 species of felids. The number of WBCs correlated with the body masses of animals: large cats had more WBC, which may be due to greater risks of infection associated with larger body surface, lifespan and home range size. For the first time we found obvious differences in the number of WBC types. Large cats also had more neutrophils and monocytes but fewer lymphocytes than smaller cats. The ratio of neutrophils to lymphocytes is greater in large felids. This phenomenon may be related to diet (relative prey size and kill utilization time), which suggests regular contact of large cats with bacterial and protozoal pathogens in contrast to the small cats.

Highlights

Hematological characteristics of different species depend on the habitats and environmental conditions where the species have evolved [1,2,3]
Hematological analysis detects the parameters related to oxygen transportation (number of red blood cells (RBCs, erythrocytes), their volume, hemoglobin concentration and hematocrit), blood coagulation and immunity (total number of white blood cells (WBCs, leukocytes) and their different types)
Total WBC number in mammals correlated with species-specific body mass: larger species had more WBCs [5,6,7,8]

Summary

Introduction

Hematological characteristics of different species depend on the habitats and environmental conditions where the species have evolved [1,2,3]. Total number of WBCs and their different types as the index of immunity are the key points of several surveys in primates [4,5], carnivores [6] and rodents [7]. These multispecies studies determined some factors affecting the total number of WBCs in different species. Total WBC number in mammals correlated with species-specific body mass: larger species had more WBCs [5,6,7,8]. Whether WBC number and body mass are connected in carnivores remains largely unknown. Nunn and coauthors [6]

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