Thyroid parameters in tortoises and turtles frequently presented at the veterinary
practise
The present study is concerned with the examination of thyroid parameters in those tortoisespecies
frequently presented at the veterinary practise. 338 tortoises and turtles were
examined over a period of one year. The examinations included case history, clinical
examinations, diagnosis and determination of fT3, fT4, T3, and T4 levels by way of
electrochemiluminescence immunoassay and sonographic examinations of the thyroid gland
with determination of the thyroid size by measuring.
One of the first steps was to determine the thyroid hormone concentrations of fT3, fT4, T3,
T4 in 103 healthy tortoises and turtles. Subsequently the levels were examined for
dependencies regarding species, age, sex, and season. This revealed significantly higher fT4-
and T4-concentrations in turtles compared to tortoises. A diagnostical dependence regarding
age, sex, and season could not be detected. Accordingly a reference range, defined as 95%
percentile interval, was established for those tortoises frequently presented at the veterinary
practise (Testudo hermanni, Testudo graeca, Testudo marginata, Agrionemys horsfieldii).
In a second step the fT3, fT4, T3, and T4 concentrations of 235 ill tortoises were determined.
The animals were divided according to manner and severity of their illness into three groups
(slightly ill animals, profoundly ill animals, and animals under medication by Allopurinol).
Significant differences were revealed in the thyroid hormone concentrations of healthy
compared to profoundly ill animals. The main parameter for diagnostic use, it became, is
apparently fT3. There is evidence suggesting an increase of this parameter in excess of the
reference range indicates that the animals suffer from a severe illness with possibly fatal
consequences. This test has a high specificity and a comparatively low sensitivity.
At the same time the thyroid glands of 338 tortoises were examined sonographically. Position,
shape, echogenicity and echotexture were described.
The maximum diameter of the thyroid gland was established and put in relation to the body
weight. Dependencies between the size of the thyroid and the state of health or illness on the
one hand and the concentration of thyroid hormones on the other hand were checked. This
showed that animals under medication by Allopurinol frequently feature bigger thyroid glands
than healthy animals. A correlation between thyroid hormone concentration and thyroid-size
could not be proven.
The results of this study are compared to evidence from to literary references and the
diagnostical applicability is discussed.