Presence of Selective Brain Cooling in Carnivorans

As the world’s climate becomes increasingly arid due to anthropogenic climate change, it becomes more pertinent to understand how species will respond to these changes on a physiological level. One of the most endangered mammalian groups is Carnivora, with as high as 25% of species in danger of extinction (IUCN Red List). With numerous mammalian carnivores serving as keystone species, the result of this biodiversity loss would send devastating cascades throughout global ecosystems (Maehr et al 2001). Previous studies have found that members of Artiodactyla utilize a meshwork of cranial vasculature known as the carotid rete to generate a counter-current heat exchange between blood travelling to the brain from the heart via the central arteries and cooler blood returning from the nasal and oral mucosa in a process known as selective brain cooling (SBC) to reduce thermal stress on the brain (O’Brien 2018). This makes them well-adapted to living in arid environments. Concurrently, carnivorans often occupy the same ecological communities as artiodactyls, and therefore need to be able to withstand the same environmental conditions. However, previous studies of the carnivoran rete have focused solely on anatomical mapping in domestic animals, like cats and dogs (Baker & Hayward 1967; Baker 1972; Kier et al 2019), and have ignored wild carnivores. The taxonomic distribution of the carotid rete in carnivorans remains largely unknown. In this study, I outline how I will take the first steps in finding answers to questions about the carnivoran rete: 1) identify the rete’s structure and osteological correlates within these species; 2) use this survey to identify which carnivorans even possess a carotid rete. This can be accomplished by computationally isolating cranial vasculature in injected CT scans, and aggregating features into a character matrix to distinguish similarities and variations across Carnivora. Only once this is complete can further investigations into more nuanced inquiries, like the dependence of environmental and habitat parameters on the presence or absence of SBC or the breadth of SBC in paleontological specimens, be made.