Meeting Abstract

P2-19   -   Comparative cardiac anatomy in the snow leopard ( Panthera uncia) and lion ( Panthera leo) Nagy, S*; Smith, HF; College of Veterinary Medicine, Midwestern University, Glendale, AZ; Department of Anatomy, Midwestern University, Glendale, AZ hsmith@midwestern.edu https://www.midwestern.edu/academics/our-faculty/heather-smith-phd.xml

Snow leopards (Panthera uncia) are anatomically and physiologically adapted to life at high elevations in the alpine forests of southeast Asia. In contrast to cold adaptations of P. uncia, the African lion (Panthera leo) is adapted to life on the savannah, including hunting using a combination of stealth, strength, and sprinting speed. Massive forelimbs of pantherines restrict the thoracic cavity cranially, limiting the available space for the cardiovascular system and placing additional anatomical constraints on the heart. Detailed dissections and data collection were conducted on hearts of 22-year-old male and 16-year-old female snow leopards and 22-year-old female lion donated postmortem following medically necessary euthanasia. The supraventricular crest, which functions to guide blood flow and empty right atrium, previously described in P. tigris, is also present in P. uncia. The musculi pectinati of the auricles extend into the right atrium allowing the right atrium to generate more forceful contractions. This morphology likely increases the flow of blood from the right atrium to the rest of the heart thereby increasing cardiac output. The most notable difference among felid taxa is the presence of a prominent moderator band (septomarginal trabecula) in the right ventricle of P. leo, in contrast to an absent moderator band in P. uncia, P. tigris, and other felids. The moderator band facilitates transmission of electrical signals from the interventricular septum to the anterior papillary muscle. Its marked presence in P. leo likely facilitates the increased cardiac strength required by lions to hunt on the African plains. Overall, cardiac anatomy is relatively conserved among published felid taxa with increased development in pantherines of features that facilitate blood flow through the heart and prevent valve regurgitation.