Sunita Janssenswillen and colleagues (2021) analyzed secretions from the anal sac glands of 17 domestic dogs and discovered the consistent presence of three related odorant-binding proteins (OBPs). These proteins were previously known to mediate scent communication in non-carnivoran mammals, such as rodents, but had not been linked to carnivores’ anal sac glands until now.
The team found that the genes encoding these OBPs form a cluster on the X chromosome, a locus also conserved across many placental mammals. Phylogenetic analyses indicated a dynamic history of gene duplication and loss, but with persistent functional conservation. This suggests that while the specific glands or tissues used for chemical communication vary across species, the underlying protein repertoire has remained stable through mammalian evolution.
In dogs, anal sac secretions are already known to convey social and territorial information via volatile compounds produced by symbiotic bacteria. The discovery of OBPs in this context demonstrates that protein-based mechanisms also play a key role, bridging the gap between carnivoran and non-carnivoran chemical signaling systems.
This research not only clarifies the biological basis of dog scent-marking behavior but also highlights how deeply rooted chemical communication is in mammalian evolutionary history. Despite shifts in anatomical structures, the proteins involved in signaling have retained their function over millions of years.
Source: Janssenswillen, S., Roelants, K., Carpentier, S., Rooster, H., Metzemaekers, M., Vanschoenwinkel, B., Proost, P., & Bossuyt, F. (2021). Odorant-binding proteins in canine anal sac glands indicate an evolutionarily conserved role in mammalian chemical communication. Journal: BMC Ecology and Evolution, Volume 21. Publication Date: September 26, 2021. Authors: Sunita Janssenswillen et al.
