Phoca vitulina swallowing physiology using videofluoroscopy: Creating a comparative rehabilitation model

Abstract

BackgroundUp to 150 wild harbor seal pups (Phoca vitulina) are admitted annually to our rescue centre. All require medical management including gavage feeding until weaned to whole fish prior to release back to the wild. The rehabilitation model is personnel intensive requiring animal restraint and force feeding. To the best of our knowledge, no systematic imaging has been conducted on the upper aerodigestive tract of wild seal pups. As a result, the information regarding their swallowing physiology is limited as are ways in which to optimize their feeding and swallowing rehabilitation. Our objectives were to develop a videofluoroscopic swallowing study (VFSS) protocol and to determine the feasibility of conducting a VFSS with a wild seal.MethodsFeasibility parameters included the determination of: contrast delivery methods, image capture and analyses, and the operational and infrastructure requirements. A Siemens mobile c‐arm fluoroscopy unit and retrofitted tub were utilized for imaging. After thawing, we injected whole flash‐frozen herring with liquid barium suspension (105% w/v). Recently weaned seals (N = 2) were imaged at 30 frames per second with loss less capture. Two blinded raters evaluated swallow physiology across 6 metrics with disagreements resolved by consensus. Results were summarized descriptively.ResultsWe conducted a freely‐behaving videofluoroscopic swallowing study on two infant seals (1 male: 8 wks, 3 d; 1 female: 5 wks, 3 d). Personnel included veterinarian, veterinary technicians (2), imaging technician and VFSS raters (2). Five boluses were administered to each seal (67–90 g each) with a total exposure of 2 min, 54 sec. We identified three distinct swallow phases: preparatory (preswallow), oropharyngeal and esophageal. The preparatory phase was characterized by airway closure and base of tongue (BOT) positioning. The oropharyngeal phase included bolus transport via BOT retraction, repeated anterior‐superior hyolaryngeal excursion, and posterior pharyngeal wall contraction. Bolus propulsion to the stomach occurred during the esophageal phase.ConclusionsWe have successfully conducted the first‐ever VFSS on wild seal pups. With this protocol, we will gather the first normative swallowing data, enhance diagnostic capabilities and potentially improve feeding and swallowing rehabilitation for this population. Ultimately, this will inform our development of the first cross‐species conceptual swallowing framework between seals and humans facilitating a synergistic knowledge translation model.Support or Funding InformationDr. Skoretz’ startup funding from the Faculty of Medicine and the School of Audiology and Speech Sciences at UBC provided support for this project.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.