Abstract
A group of 21 loggerhead sea turtle hatchlings (Caretta caretta) belonging to the same nest were included in a head-starting (H-S) program. The animals were divided into two groups and maintained in two different rehabilitation centers. Four animals from center A started showing clinical signs suggestive of thyroid pathology (goiter), including generalized oedema, lethargy, dehydration, intestinal hypomotility and thyroid gland enlargement as well as metabolic bone disease. Additionally, three other hatchlings from the same group died without previous signs of illness, and histopathology revealed severe diffuse thyroid follicular hyperplasia and hypertrophy. All hatchlings were transferred to center B (Oceanogràfic of Valencia) and were subjected to a complete clinical examination for suspected thyroid disease. Blood was collected for routine hematology and biochemistry analysis and additional determination of TSH, T4 and fT4 in serum. Ultrasonographic evaluation of the thyroid gland was also performed. The same diagnostic procedures were performed in hatchlings from other nests too. All turtles coming from this nest had significantly decreased fT4 and T4 values compared to neonates from other geographical areas. Clinically affected animals had a more pronounced decrease in thyroid hormone values and also had an increase in ultrasonographic size of the thyroid gland when compared with the non-symptomatic group. Treatment was initiated only in symptomatic animals by administering synthetic levo-thyroxine and iodine supplementation. Within 1 month, an increase in T4 and fT4 values were observed, and clinical signs resolved. The available information regarding etiology, occurrence and treatment of goiter and thyroid disease in reptiles and wildlife medicine is scarce, but possible causes include suboptimal dietary iodine or other nutritional deficiencies, exposure to goitrogenic substances or endocrine-disrupting contaminants, genetic predisposition or a combination of them.1 All the turtles from the same nesting area had decreased thyroid hormone values, indicating that the environment might be a determining factor in the development of clinical signs.
*Presenting author
Literature Cited
1. Pajdak-Czaus J, Terech-Majewska E, Będzłowicz D, Mączyński M, Krystkiewicz W, Łabuć S, Platt-Samoraj A, Szweda W. Applicability of thyroxine measurements and ultrasound imaging in evaluations of thyroid function in turtles. J Vet Res. 2019;63(2):267–73.