Steatitis in Cold-Stunned Kemp’s Ridley Sea Turtles (Lepidochelys kempii)

SIMPLE SUMMARY: Kemp’s ridley turtle is the rarest species of sea turtle and is considered to be critically endangered. While the main habitat of adults is the Gulf of Mexico, juveniles forage off the northeastern United States during summer. However, when juveniles fail to leave this area in autumn before water temperatures fall below 10 °C, they become cold-stunned and strand on beaches. Every winter, there are coordinated efforts to rescue and rehabilitate these stranded sea turtles. Cold-stunned sea turtles require supportive care because they suffer from a variety of medical problems, including steatitis, or inflammation of fat tissue. The goal of this study was to further understand steatitis by investigating blood analytes involved with vitamin E metabolism, and investigating microscopic changes that occur in affected fat tissue. We found that various contributing factors may play a role in the development of steatitis. Based on these findings, we conclude that enhanced vitamin E supplementation and dietary modification during rehabilitation may be useful in preventing and treating steatitis. The results from this study will contribute to improving rehabilitation outcomes and successful release of this endangered sea turtle species. ABSTRACT: The pathogenesis of steatitis that infrequently occurs in cold-stunned Kemp’s ridley sea turtles (KRT; Lepidochelys kempii) has been undetermined. The objectives of this study were to investigate the clinical (n = 23) and histologic findings (n = 11) in cold-stunned KRT, and to compare plasma concentrations of α-tocopherol (vitamin E), thiobarbituric acid reactive substances (TBARS), and the TBARS to vitamin E (T/E) ratio (an assessment of oxidative stress) between cold-stunned KRT with clinically and/or histologically confirmed steatitis (n = 10) and free-ranging KRT (n = 9). None of the cold-stunned turtles had clinically detectable steatitis at admission, and the median number of days to diagnosis of steatitis was 71 (range 33–469). Histologic findings of affected adipose tissue included heterophilic (n = 9) and/or histiocytic (n = 5) steatitis, fat necrosis (n = 7), myonecrosis (n = 2), and intralesional bacteria (n = 6). Cold-stunned KRT had significantly lower plasma vitamin E concentrations (median = 3.5 nmol/g), lower plasma TBARS concentrations (median = 1.6 nmol/g), and higher T/E ratios (median = 0.50), than controls (62.3 nmol/g; 2.1 nmol/g; 0.03, respectively). These results suggest a multifactorial etiology for the development of steatitis in KRT during rehabilitation, including tissue injury, septicemia, and various factors resulting in imbalances of anti-/oxidative status. By highlighting the need to provide more effective vitamin E supplementation, and the need to re-assess specific components of the diet, this study may lead to reduced incidence and improved medical management of steatitis in cold-stunned sea turtles.