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Are sutures a pathway to infection? A multidisciplinary assessment of wound healing in sharks following internal acoustic tagging

Brittany Heath , Charlie Huveneers, Ryan Hesse, Lewis Vaughan, Ondi L. Crino, Chloe N. Roberts, Xanthe Venn , Jordan Matley

Abstract

Context: Acoustic telemetry often involves a surgical method of internal tagging, wherein an animal is incised, a transmitter (hereafter referred to as a tag) internally inserted into the coelomic cavity, and the incision closed with sutures to aid wound closure, healing, and tag retention. However, the act of tagging leads to additional handling and exposure to foreign materials (e.g., sutures), potentially increasing stress and the possibility of infection or fatality. Aims: We assessed whether the absence of sutures would result in similar or different healing responses compared to incisions closed with sutures. Methods: A 42-day captive study measured physical (i.e., macroscopic assessment of incision healing progress), bacterial colonisation (i.e., colony forming units), and blood chemistry (i.e., glucose and lactate concentrations) responses to the two internal acoustic tagging procedures (i.e., with and without sutures) in twelve Port Jackson sharks (Heterodontus portusjacksoni). Key results: Macroscopic measurements (i.e., incision length and width) healed at different rates but were comparable between tagging procedures across the 42-day study. Still, there was a higher presence of inflammation and incisional swelling in sutured incisions and one case of visceral protrusion in a non-sutured incision. Sutured incisions had significantly more bacteria present than non-sutured incisions, despite the use of autoclaved surgical tools and surgeries performed in a controlled environment. Tag retention was 100% in both treatments. Conclusion: Combined, these findings highlight that healing was broadly similar regardless of suturing and not suturing, and that sutures may offer a pathway to bacterial infection. However, the potential lethal impact of visceral protrusion from non-sutured incisions is a critical concern. Nevertheless, further work should examine whether smaller incisions/tags and different tagging sites (e.g., left or right side, near or far from pelvic) could limit protrusions. Implications: This research on wound healing contributes to our limited understanding of elasmobranch healing and tagging effects, which is an important consideration when minimising welfare impacts on animals used in research.

WR25009  Accepted 16 July 2025

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