Comparative evaluation of the cadaveric, radiographic and computed tomographic anatomy of the heads of green iguana (Iguana iguana) , common tegu ( Tupinambis merianae) and bearded dragon ( Pogona vitticeps)

BackgroundRadiology and computed tomography are the most commonly available diagnostic tools for the diagnosis of pathologies affecting the head and skull in veterinary practice. Nevertheless, accurate interpretation of radiographic and CT studies requires a thorough knowledge of the gross and the cross-sectional anatomy. Despite the increasing success of reptiles as pets, only a few reports over their normal imaging features are currently available. The aim of this study is to describe the normal cadaveric, radiographic and computed tomographic features of the heads of the green iguana, tegu and bearded dragon.Results6 adult green iguanas, 4 tegus, 3 bearded dragons, and, the adult cadavers of : 4 green iguana, 4 tegu, 4 bearded dragon were included in the study. 2 cadavers were dissected following a stratigraphic approach and 2 cadavers were cross-sectioned for each species. These latter specimens were stored in a freezer (−20°C) until completely frozen. Transversal sections at 5 mm intervals were obtained by means of an electric band-saw. Each section was cleaned and photographed on both sides. Radiographs of the head of each subject were obtained. Pre- and post- contrast computed tomographic studies of the head were performed on all the live animals. CT images were displayed in both bone and soft tissue windows. Individual anatomic structures were first recognised and labelled on the anatomic images and then matched on radiographs and CT images. Radiographic and CT images of the skull provided good detail of the bony structures in all species. In CT contrast medium injection enabled good detail of the soft tissues to be obtained in the iguana whereas only the eye was clearly distinguishable from the remaining soft tissues in both the tegu and the bearded dragon.ConclusionsThe results provide an atlas of the normal anatomical and in vivo radiographic and computed tomographic features of the heads of lizards, and this may be useful in interpreting any imaging modality involving these species.

[1]  H. H. Bawden.  The Nose and Jacobson's organ with special references to Amphibia , 1894 .

[2]  F. H. Edgeworth,et al.  The cranial muscles of vertebrates , 1937 .

[3]  R. Graczyk.  The eye. , 1955, Radiography.

[4]  T. M. Oelrich.  The anatomy of the head of Ctenosaura pectinata (Iguanidae) , 1956 .

[5]  Carl Gans,et al.  Biology of the Reptilia , 1969 .

[6]  J. Dequeker,et al.  [Metabolic bone diseases]. , 1973, Rhode Island dental journal.

[7]  James R. Spotila,et al.  Biology of the Reptilia , 1984 .

[8]  J. Smallwood,et al.  ANATOMIC ATLAS FOR COMPUTED TOMOGRAPHY IN THE MESATICEPHALIC DOG: HEAD AND NECK , 1992 .

[9]  S. Silverman.  Diagnostic imaging of exotic pets. , 1993, The Veterinary clinics of North America. Small animal practice.

[10]  D. Mader.  Reptile medicine and surgery , 1996 .

[11]  B. L. Pear.  The radiograph. , 1998, AJR. American journal of roentgenology.

[12]  H. Mcallister,et al.  Diagnostic Radiology and Ultrasonography of the Dog and Cat , 2000 .

[13]  M. Garner,et al.  Neoplasia of reptiles with an emphasis on lizards. , 2003, The veterinary clinics of North America. Exotic animal practice.

[14]  M. Morgante,et al.  Relationship between metabolic bone disease and bone mineral density measured by dual-energy X-ray absorptiometry in the green iguana (Iguana iguana). , 2004, Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association.

[15]  D. Mader.  Chapter 61 – Metabolic Bone Diseases , 2006 .

[16]  S. Silverman.  Chapter 29 – Diagnostic Imaging , 2006 .

[17]  D. Mader.  Chapter 42 – Abscesses , 2006 .

[18]  D. Mader,et al.  Chapter 35 – Surgery , 2006 .

[19]  H. Steinmetz.  Reptile Medicine and Surgery, 2nd Edition , 2009 .

[20]  T. Tully,et al.  Diagnostic Imaging of Exotic Pets , 2007 .

[21]  P. Kass,et al.  Comparison of ophthalmic measurements obtained via high-frequency ultrasound imaging in four species of snakes. , 2007, American journal of veterinary research.

[22]  M. Knipe.  Principles of neurological imaging of exotic animal species. , 2007, The veterinary clinics of North America. Exotic animal practice.

[23]  S. Hernandez-Divers,et al.  Evaluation of transcutaneous pulmonoscopy for examination and biopsy of the lungs of ball pythons and determination of preferred biopsy specimen handling and fixation procedures. , 2008, Journal of the American Veterinary Medical Association.

[24]  S. Perry,et al.  Effects of preoperative administration of butorphanol or meloxicam on physiologic responses to surgery in ball pythons. , 2008, Journal of the American Veterinary Medical Association.

[25]  G. Oechtering,et al.  Computed tomography for the diagnosis and treatment monitoring of bacterial pneumonia in Indian pythons (Python molurus) , 2008, Veterinary Record.

[26]  S. Hernandez-Divers,et al.  Ultrasonographic appearance of the coelomic cavity in healthy green iguanas. , 2008, Journal of the American Veterinary Medical Association.

[27]  S. Evans.  The skull of lizards and Tuatara , 2008 .

[28]  Ronald E. Goldstein,et al.  Principles and techniques , 2009 .

[29]  Elisabeth S. Vrba,et al.  The Fossil Record and Evolution of Bovidae: State of the Field , 2009 .

[30]  G. Oechtering,et al.  Computed tomography of the lung of healthy snakes of the species Python regius, Boa constrictor, Python reticulatus, Morelia viridis, Epicrates cenchria, and Morelia spilota. , 2009, Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association.

[31]  T. Banzato,et al.  Cross-sectional anatomy of the rabbit neck and trunk: comparison of computed tomography and cadaver anatomy. , 2009, Research in veterinary science.

[32]  P. O’Higgins,et al.  The head and neck muscles associated with feeding in Sphenodon (Reptilia: Lepidosauria: Rhynchocephalia) , 2009 .

[33]  R. Bennett,et al.  Evaluation of the histologic reactions to commonly used suture materials in the skin and musculature of ball pythons (Python regius). , 2011, American journal of veterinary research.

[34]  Sonia M. Hernandez,et al.  Laboratory reptile surgery: principles and techniques. , 2011, Journal of the American Association for Laboratory Animal Science : JAALAS.

[35]  J. Saunders,et al.  Veterinary computed tomography , 2011 .

[36]  R. Bennett,et al.  Clinical and histologic effects of intracardiac administration of propofol for induction of anesthesia in ball pythons (Python regius). , 2011, Journal of the American Veterinary Medical Association.

[37]  A. Horvai,et al.  Metabolic bone diseases. , 2011, Seminars in diagnostic pathology.

[38]  T. Banzato,et al.  Evaluation of radiographic, computed tomographic, and cadaveric anatomy of the head of boa constrictors. , 2011, American journal of veterinary research.

[39]  T. A. Jenssen.  Society for the Study of Amphibians and Reptiles , 2012 .

[40]  Alan Perkins,et al.  Diagnostic imaging , 2012, The Lancet.

[41]  R. Shine.  Reptiles , 2004, Current Biology.