November 26, 2018

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

Borzoi dogs are considered sighthounds, dogs which hunt down fast-moving prey and relay primary on their eyes as opposed to scent. Supposedly several centuries old, the Borzoi is assumed to be a "crossbreed... between Asian or eastern sighthounds and wolf-like dogs or even the wolf itself". Over time sight hounds developed a specialized skull to emphasize this sight trait with the additional reduction of olfactory abilities. However, this is an assumption on part due to no one studying the turbinal skeleton of sighthounds with the exception of veterinarians very rarely for nasal cancer. 

This study focuses on the differences between Borzoi, other sighthounds like Saluki, as well as more scent orientated canines like German shepherds and Eurasian wolves' turbinals as any small inner working of the olfactory part of their skull. The skulls of seven borzois, 1 saluki, 3 German shepherds, and 3 Eurasian wolves where used for this comparison, each one chosen for the "the degree of completeness of the maxilloturbinal and nasoturbinal as viewed through the nasal opening". To get a complete view of the inner nasal structure of the skulls a uCT scan is performed each skull and used to create 3d models of the turbinal skeleton. A 3d model of the saluki was not possible due to the tissue covering it. From here dimensions of each skull is measured to find the volume of each and cross-section bone slices are used to measure surface density. Using this info, the lamellae of the turbinal is measured which indicates the size of the surrounding space.

Looking at the overall morphology between the skulls leads to some surprising results with interturbinals in the 3 ethmoturbinals and 3 frontoturbinals varying between individuals as opposed to breed and species. However, it was discovered that interturbinals in the between 2 and 3 are completely absent in wolves while present in some of the dog skulls. The saluki and borzoi shared the same number of turbinals compared to the German shepherd and wolf.

Looking closer at the borzois, comparing the juvenile to the adult skulls showed identical morphology.  There is son compression due to the narrow shape of the snout and branching of the maxilloturbinal. However, comparing it to the saluki shows virtually no difference and even overall there is little difference in turbinal skeleton between all the species studied. The assumptions held by the researchers do not hold up, as almost no significant difference in olfactory build can be derived between breeds, accept some evidence shows that sighthounds may develop their lamina semicircularis, earlier than their frontoturbinals. Overall, it is concluded that some more study is needed with more short-snouted and medium snout sized breeds, and, that in general, "morphological studies alone cannot help to elucidate the correlation of the turbinal complexity and olfactory performance in" dogs.

Wagner, F., Ruf, I., Who nose the borzoi? Turbinal skeleton in a dolichocephalic dog breed (Canis lupus familiaris). Mammal. Biol. (2018), https://doi.org/10.1016/j.mambio.2018.06.005

Access full article at : https://doi.org/10.1016/j.mambio.2018.06.005

Reviewed by Sydnie Dillon, 11/25/2018