Who nose the borzoi? Turbinal skeleton in a dolichocephalic dog breed (Canis lupus familiaris)

Abstract

The domestic dog (Canis lupus familiaris) shows a high intraspecific morphological diversity in its facial shape with a less well-known effect of different snout length types on the intranasal structures, i.e. the turbinal skeleton. Sighthounds are supposed to have a less developed sense of smell in favor of their visual abilities. It has been proposed that within the small space of a sighthound’s slender snout the turbinals are less in number and reduced. In a recent ethological study the English greyhound failed at an odor-discrimination task. To test this hypothesis we performed a morphological and morphometric analysis of the turbinal skeleton in the borzoi as a member of the sighthound group based on high resolution computed tomography. For comparison we included saluki, German shepherd and Eurasian wolf in our study; borzoi and German shepherd are represented by different ontogenetic stages. Histological serial sections of a prenatal whippet were investigated to confirm identification of single turbinals. In order to elucidate the proportions and complexity of the turbinal skeleton we applied a new morphometric approach. Our results clearly show no significant difference in the number of turbinals in all investigated specimens but an unexpected high number of interturbinals in the sighthounds in comparison to the German shepherd and the wolf, a large surface area and a high surface density and turbinal complexity. Consequently, the turbinal morphology of the borzoi and most probably the sighthound group in general clearly shows no skeletal evidence for a reduced olfactory sense. Thus, our study demonstrates that the bony turbinals alone cannot provide a proxy for olfactory abilities in dogs. The epithelium, the olfactory receptors with their corresponding genes, the brain, and the ethology need to be considered as well when analyzing a species’ olfactory performance.