Ultrasound Insights: New Reference Data for Kidney and Gonad Imaging in Lizards

Comparative Sonographic Studies of the Urogenital Tract in Lizards

Nils B. Klützow, Volker Schmidt

Background

Sonographic imaging is a key diagnostic tool for evaluating the urogenital tract in lizards, aiding the detection of renal and reproductive diseases that often present with nonspecific clinical signs. Despite its diagnostic value, species-specific reference data are limited. This study aimed to establish sonographic reference values for the kidneys, testes, and ovaries of four commonly kept lizard species—bearded dragons (Pogona vitticeps), leopard geckos (Eublepharis macularius), veiled chameleons (Chamaeleo calyptratus), and panther chameleons (Furcifer pardalis)—and to compare their anatomical and echogenic characteristics.

Methods

This prospective anatomical and analytical study included 41 clinically evaluated lizards from the University of Leipzig’s Clinic for Birds and Reptiles. Ultrasound examinations were performed without sedation using an 8–18 MHz hockey-stick and a 6–15 MHz linear transducer. Each animal was scanned in physiological posture, with sagittal and transverse images recorded for kidneys, testes, and ovaries. Organ size (length, width, height), echogenicity, and structure were assessed. Four animals that later required euthanasia were dissected for postmortem comparison. Data were analyzed using SPSS with nonparametric statistics (Spearman–Rho correlations, significance at p ≤ .05).

Results

The kidneys were visualized completely in all lizards, testes in 18 of 19 males, and ovaries in 13 of 22 females. Kidneys appeared elongated and narrow, located dorsally in the caudal coelomic cavity. Echogenicity varied by species: bearded dragons showed isoechogenic kidneys, leopard geckos had slightly hypoechogenic kidneys, and chameleons exhibited more hyperechogenic renal tissue. Males displayed distinct sexual dimorphism, including hyperechogenic chain-like or granular patterns consistent with reproductive complexes.
Testes were generally oval with homogeneous texture and low echogenicity; blood flow was weak or absent on Doppler. Chameleons’ testes were positioned cranioventrally to the kidneys, with the right testis consistently more cranial. Ovarian follicles were anechogenic and identifiable in clusters; follicular size and number varied between species. A positive correlation was found between body weight and follicle number in leopard geckos.
Postmortem findings confirmed the accuracy of sonographic measurements.

Limitations

Ovaries of chameleons and some individuals from other species could not be evaluated due to pathological or postsurgical conditions. Variability in handling and body positioning may have influenced image quality. The relatively small sample size limited statistical power, particularly for interspecies comparisons.

Conclusions

High-frequency ultrasound enables reliable visualization of the kidneys, testes, and ovaries in small lizards without sedation, providing valuable baseline data for clinical and research applications. The study establishes species-specific sonographic reference values and highlights characteristic sexual dimorphism in renal structure. These findings will support improved diagnosis of urogenital disorders and future comparative imaging studies in reptile medicine.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.