Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 ISSN: 2226-4485 (Print) Original Research ISSN: 2218-6050 (Online) DOI: 10.5455/OVJ.2023.v13.i9.2 Submitted: 15/09/2022 Accepted: 05/08/2023 Published: 30/09/2023 Computed tomography of the coelomic cavity in healthy veiled chameleons (Chamaeleo calyptratus) and panther chameleons (Furcifer pardalis) Adrián Melero1,2* , Judit Verdés2 , Yvonne Espada2,3 , Rosa Novellas2,3 , Mario Encinoso2,4 and Jaume Martorell2,3 1 Exòtica Veterinaris, Barcelona, Spain Fundació Hospital Clínic Veterinari, Universitat Autònoma de Barcelona, Barcelona, Spain 2 3 Departament de Medicina i Cirurgia Animal, Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain 4 Hospital Clínico Veterinario, Facultad de Veterinaria, Universidad de las Palmas de Gran Canaria, Las Palmas, Spain Abstract Background: Veiled chameleon (Chamaeleo calyptratus) and panther chameleon (Furcifer pardalis) are two of the most popular pet chameleons, and consequently, these species are frequently evaluated in veterinary practices. According to our review of the literature, normal computed tomography (CT) anatomy of these lizards has not been previously described. Aim: The purposes of this prospective study were to describe the normal CT anatomy of the coelomic organs in healthy patients and to provide normal reference values in these species. Methods: Seventeen clinically healthy veiled chameleons and 15 clinically healthy panther chameleons were included. All CT studies were performed with the chameleons under light anesthesia and positioned in sternal recumbency. Studies were performed with a 16-slice helical CT scanner with a slice thickness of 0.625 mm. The authors recorded qualitative and quantitative CT characteristics of the coelomic structures. Macroscopic cross-sectional anatomy was performed for comparison of the CT findings. Results: Heart, lungs, liver, including caudal vena cava, hepatic vessels, gallbladder, esophagus, stomach, intestines, gonads, fat bodies, kidneys, and urinary bladder could be visualized with CT. The spleen, pancreas, and adrenal glands could not be identified. Conclusion: This study provides a guide to the normal cross-sectional and computed tomographic anatomy of the coelomic cavity in veiled and panther chameleons. Our results could be used as a reference for future research studies or comparison of clinically ill patients. Keywords: Reptile, Lizard, Chameleon, Anatomy, Imaging. Introduction the coelomic cavity. Information related to normal Diagnostic imaging has been included in the diagnostic anatomical descriptions in some species using advanced protocols of reptile medicine for decades. Radiographic imaging techniques is limited (Gumpenberger and studies and ultrasound examinations are well- Henninger, 2001; Sochorcová et al., 2017; Sharma and established as diagnostic imaging tools in humans and Wyneken, 2019). CT has been used in the evaluation veterinary patients like reptiles. However, the presence of diseases in the skeletal system, respiratory tract, of shells, scales, and overlying structures have been reproductive tract, liver, spleen, and urinary tract in historically limiting factors for the acquisition and loggerhead sea turtle (Caretta caretta) (Arencibia et al., interpretation of diagnostic images in reptile patients 2006; Valente et al., 2007), in different snakes species: using these techniques (Gumpenberger, 2019a). Python regius, Boa constrictor, Python reticulatus, The introduction of computed tomography (CT) has Morelia viridis, Epicrates cenchria, and Morelia spilota revolutionized the practice of diagnostic imaging in (Pees et al., 2009), in captive green iguanas (Iguana reptiles. The use of CT studies also allows a better iguana) (Nardini et al., 2014), boas (Boa constrictor) interpretation of the images, above all in the chelonia (De Souza et al., 2018), sea turtles (Oraze et al., 2019), group, where the shell can hamper the assessment of and other species (Schmidt et al., 2020). *Corresponding Author: Adrián Melero Jurado. Exòtica Veterinaris, Barcelona, Spain. Email: adrian.vetexotic@hotmail.com Articles published in Open Veterinary Journal are licensed under a Creative Commons Attribution-NonCommercial 4.0 International License 1071 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 In exotic veterinary practice, veiled chameleon cranio-caudal direction with the animals positioned in (Chamaeleo calyptratus) and panther chameleon ventral recumbency (Fig. 1). All studies were obtained (Furcifer pardalis) are the most popular pet chameleon with a slice thickness of 0.625 mm, interval thickness species presented to visit in Spain. According to of 0.625 mm, collimation pitch of 0.5625:1, 120 kV, 80 our review of the literature, few descriptions of mA, field of view of 20 cm and a matrix of 512 × 512. normal CT and macroscopic cross-sectional anatomy The transverse images were reconstructed in sagittal characteristics description of F. pardalis have been and dorsal planes using multiplanar reconstruction. previously described (Sharma and Wyneken, 2019). CT images were displayed in a soft tissue window This study was designed with two objectives. First, to (window level: 350; window width: 40) and a lung describe CT features of the coelomic organs in healthy window (window level: −500; window width: 1,500). patients, and second, to provide references of normal Coelomic organs height and width were assessed on biometry in these species. the transverse images and length was assessed on the sagittal and dorsal reconstructions (Fig. 2). Materials and Methods Study population This was a prospective, anatomic, and diagnostic imaging descriptive study. The inclusion criteria required only healthy animals and all used specimens were considered healthy by complete physical examination performed by two of the authors (JM and AM) and coprology analysis results confirming that all chameleons used in the study were free of protozoans. Seventeen veiled chameleons (7 males and 10 females) and 15 panther chameleons (13 males and 2 females) from a pet shop were used for the study purpose. The owner of the pet shop permitted the use of animal data for research aims. The study protocol was reviewed and approved by the “Comissió d’Experimentació Animal- Fig. 1. Panther chameleon (F. pardalis) under alfaxalone Generalitat de Catalunya” CEA-OH/9203/1. anesthesia positioned in sternal recumbency during the CT The animals were housed in groups of two or three in study. separate terrariums equipped with ultraviolet-B lights and heat bulbs for a standardized time of 3 days before obtaining the CT images. The ambient temperature was approximately 28°C–30°C during the day, and 22°C–24°C at night. Humidity was provided with a watering artificial rain system for a minute every hour, 8 hours a day. The lighting cycles were of 14 hours of light and 10 hours of darkness. The animals were fasted for 48 hours before diagnostic imaging (based on gastrointestinal transit time previously described on bearded dragons) to ensure that the gastrointestinal tract was empty (Grosset et al., 2014). Coelomic ultrasound was performed the CT study to describe the appearance of the celomic organs and has been previously published (Melero et al., 2020). Computed tomography A coelomic cavity CT study was performed on each animal. CT was performed once in each animal. Each Fig. 2. Sagittal precontrast CT images displayed in soft tissue animal was under light anesthesia using alfaxalone window (A and F) with length and height measurements (Alfaxan® 10 mg/ml; Dechra, Worcestershire, UK) with of heart, liver, gallbladder, testes, kidneys, and fat bodies intravenous administration directly using a 26-gauge in a veiled chameleon (C. calyptratus). The precontrast butterfly catheter into the caudal vein, at a dose of CT transverse images displayed in soft tissue windows 4–6 mg/kg (Knotek et al., 2011) in healthy veiled B–E show the width and height measurements of the same chameleons. The animals were maintained with gloves organs. H, heart; RLi, right liver lobe; LLi, left liver lobe; filled with warm water during anesthesia. GB, gallbladder; RK, right kidney; LK, left kidney; RT, right The CT examinations were performed with a 16-slice testicle; LT, left testicle; RFB, right fat body; and LFB, left helical CT scanner (General Electric Brivo CT 385) in fat body. 1072 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 Nonionic iodinated contrast medium (iobitridol, The mean body weight ± SD of the animals included Xenetix® 300 mg/ml, Guerbet, Madrid, Spain) was in the study was 102.0 ± 16.8 g for veiled chameleons administered at a dose of 600 mg/kg directly into the and 141.8 ± 20.1 g for panther chameleons. The ages of caudal vein through an intravenous 26-gauge butterfly both species ranged from 8 to 18 months. catheter. Postcontrast image series were obtained at 30 The contrast study was successfully performed in seconds and 1 minute after contrast administration. 27 out of 30 animals (15 veiled chameleons and 12 All data were transferred to a workstation and analyzed panther chameleons). However, accidental contrast using a medical image viewer (RadiAnt DICOM extravasation occurred in three veiled chameleons Viewer version 4.6.9, 64-bit). and two panther chameleons, with contrast remaining Visibility, attenuation, location, anatomic landmarks, adjacent to the injection site tissue. In the postcontrast and size were registered for each organ. Attenuation study, the contrast enhancement was better observed at values of the coelomic organs were measured in 1 minute than 30 seconds after contrast administration Hounsfield units (HUs), using a circular/ovoid (Fig. 3). Therefore, 1-minute postcontrast images were region of interest (ROI) on the images of every organ used for the postcontrast attenuation measurements. following the same protocol previously used in small Heart, liver, including caudal vena cava (CVC), animals (Bertolini et al., 2006; Mallol et al., 2020). hepatic vessels, and gallbladder, esophagus, stomach, One measurement was performed for each organ in the intestines, cloaca, gonads, fat bodies, kidneys, and precontrast and postcontrast study. The image with the when distended, urinary bladder were identified in largest cross-sectional area of tissue was selected in one the CT images with the aid of the anatomical sections of the series in transverse or dorsal planes. The ROI (Fig. 4). The spleen, pancreas, and adrenal glands could included one-third to one-half of the area of the organ in not be identified. Measurement values of the liver, the selected image. This ROI area was located between testes, fat bodies, and kidneys observed in CT in veiled series manually with the maximum approximation and panther chameleons are seen in Table 1. possible. Lungs Anatomical postmortem study Due to the air attenuation of both lung fields and air One naturally dead specimen of each chameleon sacs, it was not possible to delineate well-defined limits species, with permission of the owner, was donated to between them in a soft tissue window, where they were scientific research and conserved frozen. These animals visualized together as a large air-attenuating structure did not show abnormal macroscopic findings in the (Figs. 5 and 6). Air sacs occupy more than two-thirds coelomic organs and were used to illustrate coelomic of the dorsal coelom, and lung volume is wide variable anatomy and to assess imaging findings. They were depending on their degree of expansion. Because of this, sectioned using an electric saw to correspond with the no measurements for lung size were taken. With the lung CT images. All sections were cleaned and photographed window, the lung parenchyma in the prehilar portion of the (Zwart, 1990). The CT studies of these two chameleons lungs appeared as a thin, faintly outlined, homogeneous, were performed pre and postcontrast during a period and hypoattenuating area surrounding an air-filled before the natural cause of death. cavity (Fig. 5); in the posthilar portion of the lungs, the Statistical analysis The approach of boundary limits was performed using parenchyma was barely visible. A transverse septum could an individual confidence interval. These upper and be observed as a thin, hyperattenuating structure along the lower reference limits were assessed by individual 95% confidence intervals of means (95% CI). In addition, descriptions of measurements of anatomic structures were conducted by median and their 95% CI and absolute range of them. The results will be shown using median ± SD. All statistical analyses were performed using standard software (SPSS Statistics, version 25.0). Ethical approval The study protocol was reviewed and approved by the “Comissió d’Experimentació Animal-Generalitat de Catalunya” CEA-OH/9203/1. Results A total of 17 veiled chameleons (7 males and 10 females) and 15 panther chameleons (13 males and 2 females) met the inclusion criteria for the study. Fig. 3. The postcontrast CT transverse images displayed in Given the small sample number of panther chameleon the soft tissue window show better contrast enhancement females, the authors finally decided to exclude them in the hepatic section observed at 60 seconds (B) than at 30 from the study. seconds (A) after contrast administration. 1073 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 lungs. The caudal portion of the gas-attenuating structure postcontrast sequences. Values of median HUs pre and corresponded to the air sacs (Fig. 6). postcontrast enhancement were obtained (Table 2). Heart Measurements of cardiac size were made on a sagittal The cardiac silhouette was located in the most cranial plane, similar to measurements previously described for portion of the coelomic cavity, within the rib cage, obtaining vertebral heart score (VHS) for other species showing a sternal contact. It was identified as a soft (Buchanan, 2000). Two measures were traced. A long axis is defined as the longitudinal measurement of the tissue attenuation structure with a round shape on the cardiac silhouette from the carina to the apex. The short transverse plane and a more oval appearance on a axis was perpendicular to the long axis, defined as the sagittal reconstruction (Fig. 7). This organ was better measurement between the cranial and caudal margins visualized after contrast administration displaying of the cardiac silhouette at its maximum width. These a high enhancement. However, differentiation total axes measurements were extrapolated to the between the heart chambers was not possible even on number of thoracic vertebrae from the cranial edge of the fourth vertebra. A median VHS was calculated for each species (Table 3). The posthepatic CVC segment (from the liver to the heart) was well visualized as a tubular longitudinal soft tissue attenuation structure with marked contrast enhancement localized on the most ventral aspect of the celomic cavity, slightly lateralized to the right side. The descending aorta was seen as a tubular structure, with a smaller diameter compared to the CVC, identified just ventral to the vertebral column, in the midline, and dorsal to the esophagus. Both great vessels were better recognizable on the postcontrast series, with a moderate to high contrast enhancement. Liver The liver was correctly identified in all included Fig. 4. Sagittal precontrast CT image displayed in soft tissue specimens, and it was located in the cranio-ventral window (A) and transverse cross-sectional views of gross coelom. Its anatomical landmarks were cranially the anatomical sections at the level of the liver (B), gallbladder cardiac apex, dorsally the lungs, and caudally the (C), fat bodies (D), and kidneys (E) in a veiled chameleon intestinal loops and fat bodies. Ventrally, the liver was (C. calyptratus). The right of the patient is on the left of in close contact with the ventral coelomic wall. the image. H, heart; RLu, right lung; LLu, left lung; Es, The liver was observed as a structure with low soft tissue Esophagus; RLi, right liver lobe; LLi, left liver lobe; ST, attenuating values and it was incompletely bilobed. The stomach; GB, gallbladder; RK, right kidney; LK, left kidney; right lobe was larger than the left one (Figs. 5, 6, and 8). RT, right testicle; LT, left testicle; RFB, right fat body; LFB, After contrast administration, the liver parenchyma left fat body; Co, colon. showed homogeneous contrast enhancement. The Table 1. Measurement values (median ± SD) of liver, testes, fat bodies, and kidneys observed in CT in veiled and panther chameleons. Veiled chameleon Panther chameleon Lenght (cm) Width (cm) Height (cm) Length (cm) Width (cm) Height (cm) Liver Right lobe 2.70 ± 0.42 1.04 ± 0.14 0.99 ± 0.12 2.46 ± 0.30 0.94 ± 0.14 0.72 ± 0.11 Left lobe 1.99 ± 0.30 0.78 ± 0.17 0.74 ± 0.12 1.79 ± 0.25 0.75 ± 0.14 0.65 ± 0.14 Gallblader 0.72 ± 0.09 0.55 ± 0.09 0.4 ± 0.07 0.71 ± 0.12 0.48 ± 0.07 0.44 ± 0.07 Testes Right 0.90 ± 0.08 0.84 ± 0.04 0.71 ± 0.06 0.74 ± 0.12 0.74 ± 0.12 0.51 ± 0.07 Left 0.90 ± 0.08 0.83 ± 0.10 0.73 ± 0.06 0.83 ± 0.14 0.73 ± 0.11 0.51 ± 0.06 Fat bodies Right 2.65 ± 0.46 0.64 ± 0.14 0.61 ± 0.15 2.11 ± 0.65 0.45 ± 0.15 0.44 ± 0.12 Left 2.53 ± 0.40 0.63 ± 0.13 0.62 ± 0.12 1.92 ± 0.67 0.52 ± 0.19 0.39 ± 0.08 Kidneys Right 3.17 ± 0.32 0.35 ± 0.04 0.46 ± 0.07 3.04 ± 0.26 0.45 ± 0.06 0.50 ± 0.06 Left 3.03 ± 0.33 0.38 ± 0.05 0.45 ± 0.06 2.91 ± 0.22 0.45 ± 0.05 0.50 ± 0.05 Liver: n = 17 in veiled chameleons and n = 13 in panther chameleons. Testes: n = 7 in veiled chameleons and n = 11 in panther chameleons. Fat bodies: n = 15 in veiled chameleons and n = 13 in panther chameleons. Kidneys: n = 17 in veiled chameleons and n = 13 in panther chameleons. 1074 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 Fig. 7. Fig. 7. Sagittal right paramedian postcontrast CT image displayed in soft tissue window (A) and selected corresponding transverse images represented as green line section, displayed in soft tissue window, at the level of intestines (B), fat bodies and ovaries (C), and urinary bladder Fig. 5. Sagittal precontrast CT image displayed in soft tissue (D) in a female veiled chameleon (C. calyptratus). H, heart; window (A) and selected corresponding transverse images GB, gallbladder; arrow, enhancement of the gallbladder; RLu, represented as green line section, displayed in soft tissue (B, right lung; LLu, left lung; Ov, ovaric follicles; Co, colon; D–G) and lung window (C) at the level of the lungs, liver I, intestine; RFB, right fat body; LFB, left fat body; RAS, (D), gastrointestinal tract (E), fat bodies (F), and kidneys/ right air sac; LAS, left air sac; arrowhead, ovarian vessels; urinary bladder (G) in a panther chameleon (F. pardalis). The #, caudal vein; *, Li, liver; kidneys; U, urinary bladder; RF, right of the patient is on the left of the image. RLu, right right femur; LF, left femur; PB, pelvic bone. lung; LLu, left lung; Es, esophagus; RLi, right liver lobe; LLi, left liver lobe; St, stomach; I, intestine; GB, gallbladder; RK, right kidney; LK, left kidney; RT, right testicle; LT, left hepatic veins and CVC were better defined from the testicle; Co, colon; RFB, right fat body; LFB, left fat body; adjacent parenchyma as a hyperattenuating tubular U, urinary bladder with intraluminal content (urate salts) in structure. The liver measurements are included in the lumen visualized as multiple irregular mineral attenuating Table 1 and pre and postcontrast attenuation values are structures. included in Table 2. Gallbladder The gallbladder could be identified in the caudoventral border of the liver, between the two lobes, located in the ventral aspect of the medium coelom. It was slightly lateralized to the right side of the body and the intestinal loops and fat bodies were its caudal landmark. The gallbladder was observed in all veiled and panther chameleons as a fluid attenuating circular structure (Figs. 5 and 6) with no visible wall in precontrast images. In postcontrast images, the thin wall of the gallbladder enhanced homogeneously, and the content was hypoattenuating in comparison with the liver parenchyma (Fig. 7). Gallbladder measurements are provided in Table 1 and Fig. 6. Sagittal right paramedian precontrast CT image attenuation values in Table 2. displayed in soft tissue window (A) and selected Gastrointestinal tract corresponding transverse images represented as green line The esophagus (Figs. 5 and 6) was visualized in all section, displayed in soft tissue window at the level of the animals and located dorsal to the liver, being visible as gallbladder (B), fat bodies (C), and kidneys/urinary bladder (D) in a veiled chameleon (C. calyptratus). H, heart; RLu, a tubular structure with soft tissue attenuation that was right lung; LLu, left lung; Es, esophagus; RLi, right liver continuous with the stomach caudally. lobe; LLi, left liver lobe; GB, gallbladder; RK, right kidney; The stomach was visible as a tubular and elongated LK, left kidney; RT, right testicle; LT, left testicle; I, intestine; soft tissue attenuation structure. In all animals, it was RFB, right fat body; LFB, left fat body; U, urinary bladder; slightly distended with mixed fluid and gas content LF, left femur; RF, right femur; PB, pelvic bone. (Fig. 5). 1075 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 Table 2. Measurements of pre and postcontrast attenuation values (median ± SD) of liver, gallbladder, intestinal wall, testes, ovarian follicles, fat bodies, and kidneys. Veiled chameleons Panther chameleons Organs Precontrast (HU) Postcontrast (HU) Precontrast (HU) Postcontrast (HU) Liver 25.47 ± 4.23 50.12 ± 8.01 39.28 ± 11.95 50.03 ± 5.10 Gallbladder 28.91 ± 2.73 30.25 ± 7.99 36.99 ± 3.08 43.00 ± 4.01 Intestinal wall 29.07 ± 2.30 58.98 ± 8.02 34.93 ± 3.35 57.89 ± 3.02 Testes 28.28 ± 3.28 34.02 ± 3.01 23.20 ± 2.43 37.58 ± 4.98 Fat bodies −107.16 ± 8.28 NCE −95.62 ± 11.16 NCE Kidneys 33.84 ± 4.21 55.00 ± 4.00 44.52 ± 3.75 62.00 ± 5.00 Heart 29.70 ± 2.64 103.75 ± 24.89 43.15 ± 1.66 158.06 ± 32.07 (NCE): No contrast enhancement. Liver: n = 17 in veiled chameleons and n = 13 in panther chameleons. Gallbladder: n = 17 in veiled chameleons and n = 13 in panther chameleons. Intestinal wall: n = 17 in veiled chameleons and n = 13 in panther chameleons. Testes: n = 7 in veiled chameleons and n = 11 in panther chameleons. Fat bodies: n = 15 in veiled chameleons and n = 13 in panther chameleons. Kidneys: n = 17 in veiled chameleons and n = 13 in panther chameleons. Table 3. Measurement values (median ± SD) of heart and VHS observed in CT in veiled and panther chameleon. Veiled Panther Measurements chameleons chameleons Long axis (cm) 1.67 ± 0.19 1.58 ± 0.19 Short axis (cm) 0.91 ± 0.12 0.81 ± 0.09 VHS 4.61 ± 0.24 3.72 ± 0.29 The intestines were found in the caudoventral coelomic cavity, between the liver cranially, the lungs Fig. 8. Sagittal precontrast CT image displayed in soft tissue craniodorsally, and the kidneys, gonads, and pelvis window (A) and selected corresponding transverse images caudodorsally. The intestines were visualized in all represented as green line section, displayed in soft tissue animals. Intestinal loops were seen as tubular structures window at the level of the liver (B), ovaries (C), and kidneys/ with a soft tissue attenuation wall and with intraluminal fat bodies (D) in a female panther chameleon (F. pardalis). small gas bubbles (Figs. 5–7). However, the different E, eggs; RLi, right liver lobe; LLi, left liver lobe; ROv, right intestinal segments could not be identified. Only the ovary; LOv, left ovary; RK, right kidney; LK, left kidney; colon could be differentiated with gas or feces when it LFB, left fat body. was distended (Fig. 5). Pre and postcontrast attenuation values can be consulted in Table 2. soft tissue attenuating structures, mildly hypodense in Finally, the cloaca was seen in 3 of 17 (17.6%) veiled comparison to the kidneys on plain images. They show chameleons and in 2 of 13 (13.3%) panther chameleons as an irregular mineral attenuating structure located in mild diffuse contrast enhancement. the caudoventral coelom within the pelvic bones. This The testicle measurements are included in Table 1. The attenuation is caused by the presence of urate salts attenuation values in pre and postcontrast images are located within the lumen, in the most caudal part of the shown in Table 2. pelvic canal (Figs. 6 and 7). The ovaries were identified cranial to the kidneys in 4 Gonads of 10 (40%) female veiled chameleons. They could be The testicles could be visualized in all male veiled visualized as a cluster of multiple circular structures, chameleons (7/7; 100%) and in 11 of 13 (84.6%) male the ovarian follicles, (with a grape-like appearance) panther chameleons. The testicles were located in the with soft tissue attenuation in 2 of 10 (20%). Mild caudo-dorsal part of the coelom ventral to the lumbar diffuse enhancement of these structures could be region. They were delimited ventrally by the intestines observed after contrast administration (Figs. 7 and 8). and fat bodies, caudally by the kidneys, and cranially The diameter of the follicles ranged from 0.19 to by the lungs and the stomach. The right testicle was 0.40 cm. When eggs were seen (2/10, 20%), they cranial to the left one (Figs. 5 and 6). These gonads appeared as ovoid structures with alternating hyper were circular bilateral almost symmetrical homogenous and hypoattenuating layers (Fig. 8). The center of the 1076 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 egg had fluid attenuation and the peripheral line with anatomical slice. The sectional anatomy of the coelomic mineral attenuation was the shell. The size of the eggs organs in veiled and panther chameleons allows a ranged from 0.56 to 0.80 cm in width and from 0.93 to correct morphologic and topographic evaluation of 1.70 cm in length in veiled chameleons. The precontrast the anatomic structures, which is a useful tool for the attenuation range of ovarian follicles was 25.5–39 HU interpretation of the CT images. in female veiled chameleons depending on the stage All the CT study examinations were performed in of follicle and egg development. The postcontrast sternal recumbency, similar to the previously described attenuation range was 31.10–44.25 HU. technique in other reptiles (Arencibia et al., 2006; Pees Fat bodies et al., 2009; Banzato et al., 2013). Unlike ultrasound, The fat bodies could be visualized in 15 of 17 (88.2%) where lateral recumbency is recommended, for CT veiled chameleons and 13 of 13 (100%) panther in reptiles the sternal recumbency is the chosen chameleons. The fat bodies were located in the positioning, regardless of the animal shape, flattened caudoventral part of the coelom, delimited cranially by or not, as previously described in other studies in the liver and lungs and caudo-dorsally by the kidneys loggerhead sea turtles (Caretta caretta), green iguana, and pelvis. They appeared as well-defined, fusiform, and bearded dragon (Pogona vitticeps) (Valente et al., bilateral, and symmetrical homogeneous fat-attenuating 2007; Banzato et al., 2013; Melero et al., 2020). structures (Figs. 5–8). They had a wide base in the In radiography, the overlap of structures happens ventral aspect and were narrow in the apical zone, with not only in flattened patients but impairs the correct a triangular shape. identification of the coelomic organs with similar The fat body measurements are included in Table 1 and soft tissue opacity due to border effacement between the precontrast attenuation values are shown in Table 2. them. Using CT, this radiographic drawback is In postcontrast images, the fat bodies did not show avoided, enabling separate visualization of each enhancement. anatomical structures, which is even easier to achieve Kidneys in postcontrast studies. In the current study, CT allowed The kidneys were visible in all animals. They were proper identification of the coelomic structures without located in the caudodorsal coelom cavity, the cranial artifacts caused by gas from the lungs, air sacs, or pole of the kidneys was limited dorsally by the spine, intestines, as it happens in ultrasonography (Melero ventrally by the intestines, cranially by the gonads, and et al., 2020). caudally by the pelvis. The caudal pole of the kidneys In the present study, animals were under light anesthesia was seen within the pelvic canal. They appeared as for restrain for diagnostic imaging purposes in order lobulated oval and bilateral, symmetric structures to avoid motion, but also to minimize the stress of with soft tissue attenuation (Figs. 5, 7, and 8). The handling, which is proven that can increase mortality in kidneys were most easily identified in the sagittal reptile species (Rossi, 2006; Kiefer and Pees, 2011) and plane and in the postcontrast studies, showing a diffuse reduce the risk of injuries and accidents. Restriction heterogeneous contrast enhancement. The ureters could handling procedures for diagnostic imaging purpose is not be identified in any chameleon. very unlikely to result in mortality in reptiles. The kidney measurements are provided in Table 1 and The contrast study was successfully performed in 27 attenuation values in Table 2. out of 30 animals (15 veiled chameleons and 12 panther Urinary bladder chameleons). However, in five chameleons (three The urinary bladder was seen in 8 of 17 (47.1%) veiled veiled chameleons and two panther chameleons), a chameleons and in 4 of 13 (26.7%) panther chameleons. small amount of extravasated contrast remained in the It was located in the caudoventral coelom and was tissue surrounding the injection site due to the small visible as an oval structure delimited craniodorsally by diameter of the caudal vein, making this a challenging the fat bodies and ventrally by the body wall. It was procedure. The presence of contrast in the perivascular visualized in pre and postcontrast studies only in the soft tissues did not cause any adverse effects and did animals that presented urate salts in the lumen as an not hinder the interpretation of the images. irregular mineral attenuating structure (Fig. 5, 6 and 7). The contrast enhancement was better visualized after The size of the urinary bladder could not be determined 1 minute of the administration due to the low heart due to the poor visualization of the wall. The attenuation rate of these species. These results agree with the range was wide and variable because it depended on the study of Nardini et al. (2014). In green iguana, the content and amount of urates. The range was 143–295 contrast medium was observed in the CVC 3 seconds HU in veiled chameleons and 154–356 HU in panther after injection, but not in the aorta. Thirty-six seconds chameleons. after injection the contrast was visible in the liver parenchyma, and after 600 seconds the contrast was Discussion still mildly appreciable in the liver (Nardini et al., In the present study, all soft-tissue window transverse 2014). As expected, the parenchymal organs enhanced images were compared with their corresponding after contrast administration. In the same way that 1077 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 was described for captive green iguanas (I. iguana) Gallbladder size variability was observed among the (Nardini et al., 2014), no side effects were observed in chameleons of the study. This fact can be explained by any animal. the composition of the diet, the degree of contraction, Using CT in healthy veiled and panther chameleons, the blockage of parasites (such as Cryptosporidium sp., liver, including CVC, hepatic vessels, and gallbladder, Choleimeria sp.), and even the length of fasting (Al- esophagus, stomach, intestines, cloaca, gonads, fat Quraishy, 2011; Azeez et al., 2014; Melero et al., 2020). bodies, kidneys, and when distended, the urinary The specimens included in this study were provided bladder can be easily visualized. with the same type of food and fasting times. Other organs such as the spleen, pancreas, and adrenal The stomach was identified in the craniodorsal coelom glands, because of their small size, could not be seen in when it was distended with an elongated and tubular the CT examination in any animal in the current study. shape in the chameleons of this study. In contrast, the Instead, these organs were well-identified in anatomical stomach had a C-shaped appearance in the green iguana postmortem studies (Melero et al., 2020). In other and the black and white tegu (Banzato et al., 2013). species such as the green iguana (I. iguana) and the The intestines were localized immediately caudoventral black and white tegu (Tupinambis merianae) the spleen to the liver. The intestinal segments could not be could be identified in CT as a small, rounded, soft tissue differentiated due to the similar appearance along the density, partially silhouetting with the stomach. Only gastrointestinal tract as in bearded dragons, and black in the green iguana the pancreas was identified in CT and white tegu (Banzato et al., 2013). As in other reptile as a soft tissue density interposed between the small CT studies, the gastrointestinal wall stratification could intestinal loops (Banzato et al., 2013). not be differentiated, most probably due to the small The lung parenchyma was described as a homogeneous size of the patients and the technical limitations of meshlike or reticular and hypoattenuating area around spatial resolution. In dogs and cats, gastrointestinal an air-filled cavity, similar to other reptiles such as wall layers are visible in CT only in 22% of the bearded dragon, black and white tegu, ball python gastrointestinal segments, most often in the stomach (Python regius), and boa constrictor (Boa constrictor) and jejunum (Wisner and Zwingenberger, 2015). (Pees et al., 2009; Banzato et al., 2013). The transverse However, the recommended technique for a proper septum between the lungs could also be identified, in evaluation of gastrointestinal layering in chameleons is accordance with what has been described in the green ultrasonography (Melero et al., 2020). iguana (Banzato et al., 2013). The lung parenchyma The colon and cloaca could be identified when and the air sacs can be clearly observed using a lung distended with content. However, when the colon was window. Only lung reconstruction is recommended in empty, the identification was not possible because its order to evaluate these structures. attenuation was similar to the adjacent soft tissues. The The liver was encapsulated, incompletely bilobed cloaca was only identified when it contained urate salts, and the right lobe was the largest of the two lobes. which were observed as mineral attenuating structures. Similarly, in a study in black and white tegu and The gonads were easily visualized especially in bearded dragon, a liver lobe extending caudally in a reproductive mature animals. In males, although dorsolateral position was evident on the right side of not specifically evaluated in this study, there was no the coelomic cavity (Banzato et al., 2013). Comparing evidence of differences in size or appearance of the the liver attenuation values with other previous studies testes during the study; even among animals of different in green iguanas (Nardini et al., 2014), interesting and body weights in different seasons. The lack of variation relevant differences were found given the fact that even between seasons could suggest that these basal liver attenuation in iguanas was higher (77.3 ± species are sexually active throughout the year when 6.2 HU) than the postcontrast HU- values achieved for environmental conditions in captivity are favorable. the chameleons included in our study. This difference More studies would be necessary to understand the between species could be explained by different variation in the size and shape of testicles over time in liver parenchyma composition or fatty deposition in chameleons. chameleons but a histological comparative study would The ovaries were clearly identified in sexually active be necessary to compare it and find correlations. veiled chameleon females and the appearance was The gallbladder was easily identified as in previous similar to those in other species (Gumpenberger, 2019a). studies in reptiles (Banzato et al., 2013). The attenuation The inactive ovaries could not be visualized (6 of 10, of intraluminal content can vary according to the diet, 60%). The CT images of the active ovaries allowed and the presence of bile sludge or debris. Similar identification of the different stages of folliculogenesis. findings have not been found in CT studies of other When the ovaries were in the initial stages of reptiles in the reviewed literature. However, changes in folliculogenesis the follicles appeared as circular echogenicity, likely representing the same variations, structures with soft tissue attenuation and presented have also been described using ultrasonography in variable sizes. In the final stages of development, eggs chameleons and other reptiles (Martorell et al., 2004; were identified as delimited ovoid structures with Bucy et al., 2015; Melero et al., 2020). an alternating hyper and hypoattenuating layer. The 1078 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 appearance of chameleons’ follicles and eggs in CT is Other limitations of this study were age and size wide in general similar to that of CT in bearded dragons and ranges between specimens. This fact should be taken chelonians (Gumpenberger, 2019a, 2019b). The CT into consideration when applying the information study offers a much larger grayscale and is not limited of this study to other animals. The chameleons were by superimposition, each follicle, and egg is detected considered healthy based on the results of a complete and clearly evaluated, except the least developed physical examination and coprology findings. However, follicles. In the last phases of development, the eggs the presence of a subclinical disease is not uncommon could occupy two-thirds of the coelom, displacing (Garner, 2006). Blood analyses would give more the adjacent structures and especially causing lung information about the clinical status of the animal. compression. However, they were not performed in the present study The fat bodies were easily identified because of the because the owner of the animals did not allow blood lower attenuation values (fat HU) in comparison with sampling. the adjacent structures. In general, the chameleons of In conclusion, this study provides a guide to the normal the study had large fat bodies, but the size depended on cross-sectional and computed tomographic anatomy of multifactorial conditions such as the diet, physiological the coelomic cavity in veiled chameleons and panther or reproductive status, and the presence of disease chameleons. Findings can be used as a reference for (Oldham-Ott and Gilloteaux, 1997). future research studies or examination of clinically ill The CT study facilitated the evaluation of the entire patients, although comparative studies between healthy kidneys in the chameleons of the study. Because the and diseased animals are still required. caudal poles of the kidneys are located in the pelvic canal, they cannot be completely observed using Acknowledgments other imaging techniques such as radiography or This work and the research behind would not have ultrasonography. It is well known that CT allows the been possible without the exceptional support of Marc visualization of viscera avoiding the interferences and Navarro Beltran and the Department of Animal Health overlapping of different structures. In the current study, and Anatomy (Universitat Autònoma de Barcelona) and kidney attenuation was similar to the adjacent soft Albert Martínez Silvestre of the Catalonian Reptiles tissue structures. Therefore, the identification of the and Amphibians Rehabilitation Center (CRARC). kidneys was easier in the sagittal than in the transverse Conflict of interest plane and after contrast administration. The Authors declare that there is no conflict of interest. The presence or absence of the urinary bladder depends Funding on the family and gender of the reptiles. In veiled There was no funding source for this study, and it was and panther chameleons, both genders have a urinary bladder (Oldham-Ott and Gilloteaux, 1997; Rossi, all a contribution from the authors. 2006; Valente et al., 2007). Similar to the cloaca, the Data availability urinary bladder was only identified in our study when it All data supporting the findings of this study are was distended with mineral attenuating structures in the available within the manuscript and no additional data lumen, corresponding to urate salts. The measurements sources are required. of the urinary bladder size could not be performed due Author contributions to the low contrast between the urinary bladder and Conceptualization and design: AMJ, JVM, and JMM; adjacent tissues. In addition, the thin wall of the urinary acquisition of data: AMJ, JVM, MEQ, RNT, and YEG; bladder was not identified. In contrast with what was formal analysis and interpretation of data: AMJ and found in red-eared terrapins where enhancement of the JVM; writing-original draft preparation: AMJ and ureters in postcontrast studies was considered excellent JVM; writing-review and editing: AMJ, JVM, RNT, in all terrapins (Sochorcová et al., 2017), visualization YEG, and JMM. All authors have read and agreed to of ureters was not possible in either of our specimens, the published version of the manuscript. AMJ and JVM probably due to CT spatial resolution related to the are co-first authors. They contributed equally to this difference in animal size (average body weight of work. 1.16 ± 0.25 kg for the Trachemys scripta elegans compared to 102.0 ± 16.8 g for veiled chameleons and References 141.8 ± 20.1 g for panther chameleons in our study). Al-Quraishy, S. 2011. A new Choleoeimeria species One of the most important limitations of this study was (apicomplexa: Eimeriidae) infecting the gall the few female numbers in the sample population of bladder of Scincus mitranus (Reptilia: Scincidae) panther chameleons (only two specimens). For this in Saudi Arabia. J. Parasitol. 97(6), 1125–1128. reason, the authors decided to exclude these animals Arencibia, A., Rivero, M.A., De Miguel, I., Contreras, from the results. Of the 10 veiled chameleon females, S., Cabrero, A. and Orós, J. 2006. Computed different stages of breeding were found, with the tomographic anatomy of the head of the loggerhead assumption that 60% were nonbreeding phases given sea turtle (Caretta caretta). Res. Vet. Sci. 81(2), the fact that ovaries were not visualized. 165–169. 1079 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 Azeez, O.I., Meintjes, R. and Chamunorwa, J.P. 2014. Mallol, C., Altuzarra, R., Espada, Y., Tobón, Fat body, fat pad and adipose tissues in invertebrates M.R., Serrano, E. and Novellas, R. 2020. CT and vertebrates: the nexus. Lipids. Health. Dis. characterisation of feline adrenal glands. J. Feline. 13(1), 71. Med. Surg. 22(4), 285–291. Banzato, T., Selleri, P., Veladiano, I.A. and Zotti, A. Martorell, J., Espada, Y. and Ruiz De Gopegui, R. 2013. Comparative evaluation of the cadaveric and 2004. Normal echoanatomy of the red-eared slider computed tomographic features of the coelomic terrapin (Trachemys scripta elegans). Vet. Rec. cavity in the green iguana (Iguana iguana), black 155(14), 417–420. and white tegu (Tupinambis merianae) and bearded Melero, A., Novellas, R., Mallol, C., Ríos, J., dragon (Pogona vitticeps). Anat. Histol. Embryol. Martínez-Silvestre, A. and Martorell, J. 2020. 42(6), 453–460. Ultrasonographic appearance of the coelomic cavity Bertolini, G., Furlanello, T., De Lorenzi, D. and Caldin, organs in healthy veiled chameleons (Chamaeleo M. 2006. Computed tomographic quantification of calyptratus) and panther chameleons (Furcifer canine adrenal gland volume and attenuation. Vet. pardalis). Vet. Radiol. Ultrasound. 61(1), 58–66. Radiol. Ultrasound. 47(5), 444–448. Nardini, G., Di Girolamo, N., Leopardi, S., Paganelli, Buchanan, J.W. 2000. Vertebral scale system to I., Zaghini, A., Origgi, F.C. and Vignoli, M. 2014. measure heart size in radiographs. Vet. Clin. North. Evaluation of liver parenchyma and perfusion using Am. Small. Anim. Pract. 30(2), 379–393. dynamic contrast-enhanced computed tomography Bucy, D.S., Guzman, D.S. and Zwingenberger, A.L. and contrast-enhanced ultrasonography in captive 2015. Ultrasonographic anatomy of bearded green iguanas (Iguana iguana) under general dragons (Pogona vitticeps). J. Am. Vet. Med. anesthesia. Vet. Res. 10(1), 112. Assoc. 246(8), 868–876. Oldham-Ott, C.K. and Gilloteaux, J. 1997. Comparative De Souza, J.C., Fernandes, T.H., De Albuquerque, morphology of the gallbladder and biliary tract in B.M. and Costa, F.S. 2018. Quantitative computed vertebrates: variation in structure, homology in tomography of healthy adult boas (Boa constrictor). function and gallstones. Microsc. Res. Tech. 38(6), J. Zoo. Wildl. Med. 49(4), 1012–1015. 571–597. Garner, M.M. 2006. Overview of necropsy and Oraze, J.S., Beltran, E., Thornton, S.M., Gumpenberger, necropsy techniques. In Reptile medicine and M., Weller, R. and Biggi, M. 2019. Neurologic and surgery, 2nd ed. Eds., Mader, D. St Louis, MO: computed tomography findings in sea turtles with Saunders Elsevier, pp: 569–580. history of traumatic injury. J. Zoo. Wildl. Med. Grosset, C., Daniaux, L., Guzman, D.S., Weber, E.S., 50(2), 350–361. Zwingenberger, A. and Paul-Murphy, J. 2014. Pees, M., Kiefer, I., Thielebein, J., Oechtering, G. Radiographic anatomy and barium sulfate contrast and Krautwald-Junghanns, M.E. 2009. Computed transit time of the gastrointestinal tract of bearded tomography of the lung of healthy snakes of the dragons (Pogona vitticeps). Vet. Radiol. Ultrasound. species Python regius, Boa constrictor, Python 55(3), 241–250. reticulatus, Morelia viridis, Epicrates cenchria, Gumpenberger, M. 2019a. Diagnostic imaging of and Morelia spilota. Vet. Radiol. Ultrasound. 50(5), reproductive tract disorders in reptiles. Vet. Clin. 487–491. North. Am. Exot. Anim. Pract. 20(2), 327–343. Rossi, J.V. 2006. General husbandry and management. Gumpenberger, M. 2019b. Secrets within the Bony In Reptile medicine and surgery, 2nd ed. Eds., Box—inside view on chelonians (An Overview). Mader, D. St Louis, MO: Saunders Elsevier, pp: EAVDI Yearbook 2019. Cambridge, UK: EAVDI 25–41. Lt, pp: 29–54. Schmidt, L., Di Girolamo, N. and Selleri, P. 2020. Gumpenberger, M. and Henninger, W. 2001. The Diagnostic imaging of the reptile urinary system. use of computed tomography in avian and reptile Vet. Clin. North. Am. Exot. Anim. Pract. 23(1), medicine. Sem. Avian. Exotic. Pet. Med. 10(4), 131–149. 174–180. Sharma, A. and Wyneken, J. 2019. Computed Kiefer, I. and Pees, M. 2011. Computed tomography tomography. In Mader’s reptile and amphibian (CT). In Diagnostic imaging of exotic pets, 1st medicine and surgery, 3rd ed. Eds., Divers, S. and ed. Eds., Krautwald-Junghanns, M., Pees, M. and Stahl, SS. St Louis, MO: Elsevier, pp: 560–570. Reese, S. Hannover, Germany: Schlütersche, pp: Sochorcová, V., Proks, P., Cermáková, E. and Knotek, 358–367. Z. 2017. Contrast-enhanced computed tomography Knotek, Z., Hrda, A., Kley, N. and Knotkova, Z. in red-eared terrapins (Trachemys scripta elegans). Alfaxolone anaesthesia in veiled chameleon Vet. Med. 62(12), 674–680. (Chamaeleo calyptratus). In Proceedings 18. Valente, A., Cuenca, R., Zamora, M., Parga, M.L., Annual Conference ARAV, 6-12/8/2011, Seattle, Lavin, S., Alegre, F. and Marco, I. 2007. Computed WA, 2011, pp 179–181. tomography of the vertebral column and coelomic 1080 http://www.openveterinaryjournal.com A. Melero et al. Open Veterinary Journal, (2023), Vol. 13(9): 1071–1081 structures in the normal loggerhead sea turtle Zwart, P. 1990. Echsen. In Krankheiten der Heimtiere. (Caretta caretta). Vet. J. 174(2), 362–370. Eds., Gabrisch, K. and Zwart, P. Hannover, Wisner, E. and Zwingenberger, A. 2015. Gastrointestinal Germany: Schlütersche, pp: 809–858. tract. Atlas of small animal CT and MRI, 1st ed. Oxford, UK: Editorial Offices, pp: 538–550. 1081