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

• Published in: The FASEB Journal
• Main Authors: Skoretz, Stacey A, Haulena, Martin, Akhurst, Lindsaye, Johnson, Emily, Dawson, Camilla
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: harbor seal; Phoca vitulina
• Online Access: http://dx.doi.org/10.1096/fasebj.2019.33.1_supplement.lb417; https://onlinelibrary.wiley.com/doi/full-xml/10.1096/fasebj.2019.33.1_supplement.lb417; https://onlinelibrary.wiley.com/doi/full/10.1096/fasebj.2019.33.1_supplement.lb417

Background Up 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. Methods Feasibility 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. Results We 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 ...