Clinical Technique Application of Computed Tomography in Zoological Medicine

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Topics in Medicine and Surgery Topics in Medicine and Surgery

Clinical Technique: Application of ComputedTomography in Zoological Medicine

Elizabeth B. Mackey, DVM,Stephen J. Hernandez-Divers, BVetMed, DZooMed, MRCVS, Dip. ACZM,Mason Holland, VMD,and Paul Frank, DVM, Dip. ACVR

Abstract Computed tomography images generate multiple views of a target site of a patient,resulting in 2-dimensional scans of the area. This form of imaging provides visualization of internal anatomy without interference of adjacent and overlying structures, contributing toour knowledge of normal anatomy and allowing us to more accurately assess changes inclinically ill patients. Computed tomography has proven to be benecial in establishing diagnoses, prognoses, and treatment plans in numerous zoological species when used inconjunction with other imaging modalities, and with the involvement of a dedicatedradiologist. Additional studies are needed to establish protocols for image collection andcriteria for evaluating the images. Copyright 2008 Elsevier Inc. All rights reserved.

Key words: computed tomography; zoological medicine; exotic pets; reptiles; smallmammals; avian

A dvances in diagnostic techniques are continu-ously sought to assist clinical practitioners of zoological medicine with making a denitive

diagnosis, providing an accurate prognosis, and deter-mining the most appropriate treatment strategy. Many of these techniques are extrapolated from those usedin domestic animal medicine and must often be al-tered to suit the unique anatomy and physiology of zoological species. Imaging modalities, such as radiog-raphy and ultrasonography, have become part of ourstandard protocol for many cases, whereas computedtomography (CT), magnetic resonance imaging (MRI),nuclear scintigraphy, and other more advanced toolsare used to a lesser degree. An increasing number of studies are being performed with exotic pets and zooanimals, contributing to our understanding of normalanatomy, and verifying the benets of using these mo-dalities in conjunction with other diagnostic tools. TheZoological Medicine Service at the University of Geor-gia has seen an increase in client acceptance in the useof CT and MRI for bird, reptile, sh, and mammalpatients. However, there has been a disproportionate

growth in the use of CT, most likely related to its lowercosts and greater availability compared with those of diagnostic MRI evaluations.

Computed Tomography

The CT (Siemens Somatom Star CT scanner; Sie-mens Medical Solutions USA, Malvern, PA USA)

From the Zoological Medicine Service, Department of Small

Animal Medicine and Surgery, College of Veterinary Medicine,University of Georgia, Athens, GA USA, and Radiology, Depart- ment of Anatomy and Radiology, College of Veterinary Medicine,University of Georgia, Athens, GA USA.

Address correspondence to: Elizabeth B. Mackey, DVM, Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30605. E-mail: [email protected] , [email protected] .

© 2008 Elsevier Inc. All rights reserved.1557-5063/08/1703-$30.00 doi:10.1053/j.jepm.2008.05.007

198 Journal of Exotic Pet Medicine, Vol 17, No 3 ( July), 2008: pp 198–209

mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


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image is created by rotating an x-ray tube, located inthe gantry, around the anesthetized patient, who islying on the table ( Fig 1). The x-rays, which pene-trate the patient, are detected on the opposite sideof the patient. The x-ray tube emits a fan-shapedbeam of x-rays from multiple positions (often 1000or more) as it rotates around the patient. This gen-erates a “slice” of the imaged anatomy. The patient isthen moved to a position slightly further into thegantry and the next slice is imaged, while the ma-chine detects the new position of the table. Thisprocess is repeated until the region of interest hasbeen scanned. A computer built into the scannerthen uses the x-ray dose received by the x-ray detec-tors in these multiple positions to generate a map of x-ray–attenuating structures present in each cross-

sectional slice. These structures are then displayedon a computer screen using shades of gray. Theshade of gray corresponds to the x-ray–attenuatingability of the tissue, similar to that of plain radiogra-phy. The most attenuating tissues (e.g., bone, teeth)are displayed closest to white, whereas gas and fat aredisplayed closer to black. Unlike radiography, thecontrast resolution is very good, allowing differenti-ation of blood from other uids, and various soft tissues. “Windowing” and “leveling” may be thought of as adjusting the contrast and brightness levels of the image, and allow the tissue of interest (e.g., boneor lung) to be optimally displayed ( Fig 2).

A major advantage of CT over plain radiography is the ability to visualize internal anatomy without superimposition of adjacent structures. For example,

Figure 1. A Siemens Somatom AR. Star CT scanner illustrating the gantry (1) and anesthetized rabbit on the table. (2) After ensuring accuratepatient positioning, the technician moves to a safe control room to initiate scanning.

Figure 2. Transverse plane images of the midcoelom of a normal green iguana (Iguana iguana ). The same image has been windowed toenhance different tissue types. (A) Using a bone window (window width 2500, window level 480), osseous structures are optimallydisplayed. Note the bony detail of the vertebra (arrow ). (B) Using a lung window (window width 1500, window level –600), visualizationof pulmonary structures is optimized. Note the conspicuity of the septae, which dene the lobes of the posterior chamber of the lungs (arrows ).(C) Using a soft tissue window (window width 500, window level 0), soft tissue contrast resolution is maximized. Note the excellentcontrast between fat body (1) and liver (2).

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when evaluating the head, radiography results insuperimposition of the complex bones of the skull,

which often hinder evaluation of the teeth. CT al-lows for the examination of skull and dental struc-tures without superimposition. Another important benet of CT is the ability to acquire postcontrast images. Intravenous iodinated contrast media can beinjected to enhance certain tissues. Soft tissue struc-tures with abnormal vascularity due to disease (e.g.,neoplasia, inamed tissue) will have an increaseduptake of the iodinated contrast media, allowing for

differentiation from normal tissue. The imaging of large vascular structures can also be performed by administering contrast media before imaging. An-other application of CT technology is the ability toaccurately place needles or biopsy instruments intoareas of interest for diagnostic sampling of tissue oruid. For this diagnostic sampling procedure, theslice of interest is selected by the user, after whichthe position of the preferred slice of the patient isindicated by the CT scanner through the use of athin light or laser line. After placing the needle in

Figure 3. CT of the hindlimbs and tail base of a water monitor (Varanus salvator ), scanned transversely at 130 kV, 83 mA, 5.0-mm slicethickness, and 1.5 sec. This is the standard display for a CT series and provides multiple cross-sectional images. (A) Transverse plane imageat the level of the metatarsi demonstrating gross enlargement of the soft tissues of the left foot. (B) Dorsal view of a 3-dimensionalskin-surface–rendered reconstruction demonstrating the gross deformity of the left foot. (C) Dorsal view of a 3-dimensional bone-surface–rendered reconstruction demonstrating the caudal vertebrae (1), bulas (2), tibias (3), and digits (4). (D) Magnied dorsal view of a3-dimensional bone-surface–rendered reconstruction of the normal right and abnormal left hindfeet. Note the bone lysis (arrows ) associatedwith osteomyelitis of distal phalanx 1 and proximal phalanx 2 of digits 4 and 5.

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the desired location, correct positioning of the nee-dle can be veried by CT imaging before sampling.

Since its inception in the 1970s, CT has under-gone a number of important improvements. Im-proved resolution, shorter scan times, and advancedimage manipulation are some of the advantages of-fered by modern CT and computer equipment. He-lical CT involves scanning while the patient is con-tinuously moved through the gantry, which allowsshorter acquisition times. Without helical CT, thepatient must be stopped for each slice. Another fea-ture of many modern scanners is multiple slice tech-nology, where thin rows of radiograph detectorssandwiched together allow up to 256 slices to besimultaneously acquired, although 2- to 16-slice scan-

ners are the machines used most frequently at thistime. This allows further shortening of scan timesand reduces motion artifacts. Modern machines cre-ate a 3-dimensional volume of data and allow recon-struction of data into alternate planes (e.g., sagittal,obliques). The data can be manipulated in multiple

ways by the user, including 3-dimensional volumerendering. Multiple image–viewing software pack-ages provide many of the same or, often, more ad-

vanced viewing options using CT images stored onCD-ROM in standard Digital Imaging and Commu-nications in Medicine (DICOM) format. One partic-ular software package that has gained popularity isOsirix (Osirix Foundation, Geneva, Switzerland) forthe Apple Macintosh (Apple Inc., Cupertino, CA USA)

Figure 4. CT of the head of a normal rabbit, scanned transversely at 130 kV, 83 mA, 2.0-mm slice thickness, and 1.9 sec. This is the standarddisplay for a CT series and provides multiple cross-sectional images. (A) Transverse plane image at the level of the upper incisorsdemonstrating the rostral rhinarium (1) and upper incisors (2). (B) Transverse plane image at the level of the mid-diastema demonstrating the2 mandibular rami (1), tongue (2), and maxilla (3) containing the midline vomer bone and turbinate structures (arrows ). (C) Transverse planeimage at the level of the rst molar teeth demonstrating the mandible (1), tongue (2), hard palate (3), nasopharynx (4), ethmoid bone andendoturbinates (arrows ), maxilla and zygomactic arch (5), rst molars (6), and nasal bone (7). (D) Transverse cross-sectional slice at the levelof the orbits demonstrating the mandible (1), oropharynx (2), nasopharynx (3), orbits (4), olfactory bulb of brain (5), frontal bone (6), zygomaticarches (7), perpendicular plates (8), and presphenoid bone (arrow ).



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computer. The ability to see the images in a 3-dimen-sional eld is benecial in communicating with own-ers and curators, students, and other veterinarians,and, although no studies have substantiated an im-provement in diagnostic ability, clinically, these ma-nipulations appear to be very useful.

Protocol

CT is a noninvasive procedure that is of short duration.It is imperative that the patient remains immobilizedduring the scanning period. General anesthesia istypically required to achieve appropriate positioningand prevent movement between scans for all mam-mals, birds, and sh. 1-3 The appropriate protocolmust be selected based on the species, the health of the patient, and the estimated duration of the pro-cedure. Some reptiles may be immobilized with phys-

ical techniques including vasovagal response in liz-ards and taping the limbs of chelonians inside their

shells.4-7 If the head, neck, or appendages need to bescanned, anesthesia is required. 2 To maintain theirbody position during the scanning procedure,snakes must be maintained under general anesthe-sia.8 It is essential that a radiologist is consultedbefore the imaging procedure to ensure that optimalresults are obtained and diagnostic questions areadequately answered.

The endotracheal tube does not present prob-lems of superimposition in CT images as in patients

when standard radiography is used. 1 Animals aretypically placed in dorsal or ventral recumbency during the procedure. Imaging of the reptiliancoelom in lateral recumbency may result in organdisplacement, which has led to misinterpretation. 2The size and body conformation of the patient isan important consideration when determining

whether sagittal or transverse images are obtained

for patient evaluation. To completely scan a lizardor bird, fewer “slices” are required if the sections

Figure 5. CT images of a rabbit with a dental abscess associated with right maxillary premolar 2, scanned at 130 kV, 83 mA, 2.0-mm slicethickness, and 1.9 sec. (A) Craniodorsal view of a 3-dimensional skin-surface–rendered image demonstrating the gross swelling associatedwith the right maxilla (arrow ). (B) Dorsal view of a 3-dimensional volume–rendered image demonstrating the severe soft tissue swellingassociated with an abscess ( white arrow ) and the loss of mineralized bone due to osteomyelitis of the right maxilla and nasal bone (black arrow ). (C) Right craniolateral view of a 3-dimensional bone-surface–rendered image demonstrating the loss of bone associated with the rightmaxilla and nasal bone (red arrows ). (D) View of a 3-dimensional mucosal-surface–rendered image from within the caudal dorsal nasal meatusdemonstrating the abscess (1) extending into the nasal cavity.

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are scanned sagittally than if they are taken intransverse. 2

Practical Applications

Reptiles

Clinical presentations of sick reptiles are oftennonspecic, making lesion localization difcult. Al-though high-quality radiographs are often useful,interpretation can be challenging because of thesuperimposition of bone and various soft tissues.The chelonian shell and osteoderms within the skinof crocodilians and some lizards can create artifactsand reduce imaging sensitivity. In addition, reptileslack diffuse fat around their visceral organs, whichalso reduces soft tissue contrast and appreciation.

CT has been used to describe the normal anatomy of several reptiles, and this knowledge may be usedas a baseline for the clinical evaluation of un-healthy animals. 8-10 Although plain radiography iscommonly used to evaluate the musculoskeletalsystem, CT can provide better detail. The greaterdetail achieved with CT imaging may be useful forconrmation of a lesion, a more accurate descrip-tion of location and extent, and therefore, a moreaccurate prognosis ( Fig 3). 11 In one study evaluat-ing skeletal injuries of chelonians, CT was able toreveal fractures that were not apparent on plainradiographic images. 6 CT has been used for eval-uating metastases in a yellow-belly racer ( Coluber constrictor aviventris ), thus providing prognosticinformation. 12

Figure 6. CT images of a rabbit with a left mandibular dental abscess associated with premolar 2, scanned at 130 kV, 83 mA, 2.0-mmslice thickness, and 1.9 sec. Left caudolateral (A) and caudomedial (B) 3-dimensional volume–rendered views of a mandibular abscess(arrows ) demonstrating both bony proliferation and destruction typical of a dental abscess. (C) Left lateral view of a 3-dimensional-volume–rendered image demonstrating vascular (inammatory) tissue surrounding the infected area (arrow ).



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Radiography and ultrasonography of the chelo-nian reproductive tract may reveal the presence of eggs or follicles but are often inaccurate for deter-mining the precise number present. CT studies havedemonstrated 4 to 6 times more accuracy in deter-mining the precise number of eggs present in reptilespecies when compared with ultrasonography. 2 WithCT, the number can be accurately assessed along

with providing information about their size, shape,and density. Shell density measurements may evenprovide an estimation of an egg’s age. 7

The slow respiratory rate, together with the en-hanced contrast between lung parenchyma and airhas resulted in exceptional CT images of chelonianand snake respiratory tracts. 2,9 These quality imageshave the potential to detect numerous pulmonary disease conditions. 9 The CT scans were particularly informative in one study in which the majority of snakes with pneumonia, even those with severe re-spiratory tract disease, were not detected on radio-graphic evaluation. 8

Small Exotic MammalsSmall mammals, including insectivores, rodents, andlagomorphs, have become increasingly popular aspets; the rabbit ( Oryctolagus cuniculus ) is now ranked

as the third most common pet mammal in theUnited States. 13 Although overgrowth of teeth is acommon problem for many small mammals withopen-rooted incisors, it is particularly signicant inthose animals that also have open-rooted cheekteeth (e.g., lagomorpha, caviidae), because changesin the cheek teeth can develop into a more seriousdisease presentation. 4,14

Evaluating lagomorph and rodent dentition canbe particularly challenging. Oral examination is lim-ited because of the small mouth, extensive buccalsoft tissue, and structure of the temporomandibular

joint, which limits gape. 4,15,16 Oral examinations may reveal ulcers, foreign bodies, or supragingival spurs,but many dental diseases are subgingival. Standardradiography allows for visualization of the underly-ing regions, but distortion from naturally occurringcurvature of the cheek teeth along with superimpo-sition with the other teeth, maxilla, and mandiblemake radiographs challenging to interpret. 16,17 Ra-diographs of the skulls of rabbits with clinical signsattributable to dental disease may reveal severe de-formity of teeth and evidence of osteomyelitis. How-ever, radiographs are not always able to identify thespecic tooth or teeth responsible for an abscess,and they cannot denitively exclude dental disease. 17

Figure 7. CT images of a rabbit that presented with mild right exophthalmia, scanned at 130 kV, 83 mA, 2.0-mm slice thickness, and 1.9sec. (A) Radiography was unremarkable, and only mild asymmetry of the ocular and retrobulbar spaces were evident on transverse CT images.Images B and C are 3-dimensional bone-surface–reconstructed views of the alveolar bullae of the maxilla, as seen from within the left (B) and right(C) orbital spaces. Note the 2 normal nutrient foramina in both the left and right alveolar bullae (white arrows ). However, also note the abnormalnutrient foramen (black arrow ) and the stula (red arrow ) associated with root abscessation of right maxillary molar 2. In this case, 3-dimensionalreconstruction enabled a diagnosis that was impossible with radiography or standard transverse CT imaging, and also aided surgical planning.

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CT scans of normal animals can be used as compar-isons with those of clinically ill individuals ( Figs 4,5, 6 , and 7).

CT has been used to reveal a tooth root abscess andassociated osteomyelitis in a guinea pig ( Cavia porcel- lus ) in which no radiographic abnormalities wereevident. 18 In another case involving a woodchuck ( Mar- mota monax ) with unilateral nasal discharge, recon-structed 3-dimensional CT images were able to dem-onstrate the loss of turbinates and pinpoint thesource of infection as the left upper incisor root (S. J.Hernandez-Divers, unpublished case report) ( Fig 8).

With the use of CT, excellent detail is provided forthe ne bone structure of the skull and adjacent soft tissue, allowing for the detection of minor patholog-ical changes. This provides an opportunity for early intervention and thus more effective treatment. 4,16

Although CT is an excellent diagnostic tool forthe evaluation of dental disease, it has also been usedin the evaluation of exotic mammals with neoplasia.Multiple plane scans can provide information re-garding the size and local distribution of a tumor,

effects on surrounding tissues, and evaluation forpossible metastases. 19-21 This information can thenbe used to establish a prognosis, determine a surgicalplan, and monitor response to therapy. In othercases, loss of normal architecture in the nasal cavity of a rabbit due to mycobacteriosis can be fully ap-preciated by using CT imaging (unpublished casereport) ( Fig 9) . The application of CT is not limitedto small mammals, and has been shown to be valu-able in the evaluation of other zoological speciesincluding nonhuman primates and small cetaceans(Figs 10 and 11). 11

Avian Although radiography can provide quality informa-tion about the skeletal system of avian species, it isunable to provide the detail of CT in areas of signif-icant bone superimposition (e.g., avian head). Sev-eral studies have shown the relevance and practicalapplications for the use of CT in evaluating the avianhead. 2,22,23 In a study comparing CT with conven-

Figure 8. CT of the head of a woodchuck that presented with left unilateral nasal discharge poorly responsive to antibiotics, scannedtransversely at 130 kV, 83 mA, 3.0-mm slice thickness, and 1.9 sec. (A) Transverse plane image at the level of the upper incisorsdemonstrating an increased soft tissue density within the left nasal cavity (black arrow ), and fracture of the left upper incisor (white arrow ).(B) Transverse plane image at the level of the caudal diastema demonstrating loss of mineralized tissue associated with the zygomatic processand lacrimal bones (white arrow ) and increased soft tissue density within the ventral nasal meatus (black arrow ). (C) Left lateral view of a3-dimensional surface–rendered reconstruction demonstrating loss of the zygomatic process and lacrimal bones ( arrows ). (D) Caudorostralintranasal view of a 3-dimensional surface–rendered reconstruction demonstrating the nasal opening (1), vomer bone (2), nasal bone (3), andnormal medial surface of the maxilla on the right side (4). On the left side, the root of the upper incisor has abscessed through the maxillainto the nasal cavity (5).



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tional radiography, quality radiographs were ob-tained for the bony parts of the head, but CT wassuperior for evaluation of the nasal cavity and con-chae. For birds that had clinical signs of upper airway disease, CT allowed for the actual measurement of the pneumatized area, thus providing informationrelevant for treatment and prognosis. Although ra-diographs could detect changes in birds with severerespiratory pathology, only CT was able to detect early disease changes. 22 Radiographs of a yellow-naped Amazon ( Amazona ochrocephala auropalliata )

with left-sided paresis were unremarkable; however,

CT revealed hemorrhage and displacement of theright side of the patient’s brain. 1 Although it is ableto provide information about the size and shape of the avian eye, lens, and scleral rings, CT cannot differentiate intraocular structures such as pectinoculi and hemorrhage. 23 Scans were able to deter-mine the extent of a periorbital liposarcoma in an

African gray parrot ( Psittacus erithacus )24 and a bro-sarcoma on the skull of a hyacinth macaw ( Anodor- hynchus hyacinthinus ). 11

A comparison study between radiography and CThas shown that CT is more sensitive for the detection

Figure 9. CT of the nasal cavity of 2 rabbits; a normal control animal (A-C) (performed under an institutional animal care and use permit) anda clinical case of nasal mycobacteriosis (D-F), both scanned at 130 kV, 83 mA, 2.0-mm slice thickness, and 1.9 sec, with computer renderingto demonstrate bone and soft tissue-air interfaces. (A) Rostrocaudal view of a normal rabbit demonstrating the opening to the nasal cavity.(B) Close-up demonstrating an air cast within the nasal cavity. The dorsal (1), medial (2), and ventral (3) meati are clearly visible, while thevomer bone (4) and turbinates (5) have been digitally removed. (C) View of an air cast from within the caudal nasal cavity demonstrating thenasopharynx (1) continuous with the trachea (2). (D) Rostrocaudal view of a rabbit demonstrating an asymmetrical air cast within the nasalcavity (arrow ) due to nasal mycobacteriosis. (E) Close-up rostrocaudal view of an air cast of the nasal cavity demonstrating the replacementof normal meati with a large asymmetrical cavity (arrow ) due to destruction of the vomer bone and turbinates. (F) Caudorostral view of thesame area as seen from within the nasal cavity. The asymmetrical air space (arrow ), ventral surface of the dorsal nasal bone (1), and nostrilopenings (2) are visible.

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of lower respiratory tract disease in psittacines. 25 Inthe comparison study, changes associated with se-

vere disease were observed in the conventional ra-diographic images, and subtle lesions were only detected through the use of CT. 25 Radiographic eval-uation of coelomic distension in a blue and goldmacaw ( Ara ararauna ) demonstrated intestinal tract displacement suggestive of a mass. Ultrasonography conrmed a mass but was unable to determine theorigin or extent of the lesion. CT scans revealed

the distribution of the mass and that the liver was theorigin of growth. The liver tumor was eventually identied histopathologically as cystic biliary carci-noma. 11

CT studies have also been performed to developan understanding of the appearance of bone andtissue in healthy avian subjects of various spe-cies.3,22,26 A detailed understanding of what is normalin an avian species will improve our chances of de-tecting abnormalities that may be observed in clini-cally ill individuals and to assist clinicians in diagnos-ing and formulating treatment plans. Information

obtained through CT evaluation of different avianspecies may also be used to support taxonomic clas-sication and nomenclature. 27

Conclusion

Curatorial staff and exotic pet owners expect thesame high-quality medicine as is available for domes-tic animals. The use of advanced imaging in diagnos-

tic patient evaluations is increasing as well as theavailability of machines for veterinary practices.These imaging modalities have the potential to be-come part of our standard diagnostic investigationfor anatomic regions previously difcult to evaluate.

Advanced imaging, including CT, may provide ear-lier detection of abnormalities and more accurateevaluation of clinical disease. The application of 3-di-mensional rendering software allows for optimal sur-gical planning and is an excellent educational re-source for owners and veterinarians. Guidelinesneed to be established for the evaluation and inter-

Figure 10. CT images of a white-faced capuchin (Cebus capucinus ) that presented with persistent nasal discharge scanned at 130 kV, 83mA, 2.0 mm-slice thickness, and 1.9 sec. (A) Rostrocaudal view of a 3-dimensional volume rendition of the head. (B) Anteroposterior viewof a 3-dimensional bone-surface–rendered image of the skull. (C) Anteroposterior 3-dimensional bone-surface–rendered image of the openingto the nasal cavity demonstrating asymmetry of the vomer bone (1), and the palatine bones (2). (D) Caudorostral 3-dimensionalbone-surface–rendered image from within the nasal cavity demonstrating asymmetry of the vomer bone (1) and the palatine bones (2). Basedon the CT, as well as the cytologic and microbiologic ndings, this animal was successfully treated for allergic rhinitis.



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pretation of healthy zoological species, and it is im-perative that the application of these tools be sub-stantiated by evidence-based clinical research andthat board-certied radiologists are involved in thecollection and interpretation of the imaging data.

References

1. Jenkins JR: Use of computed tomography (CT) inpet bird practice. Proc Annu Conf Assoc Avian Vet 276-279, 1991

2. Orosz SE, Toal RL: Tomographic anatomy of thegolden eagle ( Aquila chrysaetos ). J Zoo Wildl Med23:39-46, 1992

3. Crossley D, Jackson A, Yates J, et al: Use of computedtomography to investigate cheek tooth abnormalitiesin chinchillas ( Chinchilla laniger ). J Small Anim Pract 39:385-390, 1998

4. Gumpenberger M, Henninger W: The use of com-puted tomography in avian and reptile medicine.Semin Avian Exotic Pet Med 10:174-180, 2001

5. McArthur S, Wilkinson R, Meyer J, et al: Medicineand Surgery of Tortoises and Turtles. Oxford,Blackwell Publishing Ltd, 2004

6. Abou-Madi N, Scrivani PV, Kollias GV, et al: Diagno-sis of skeletal injuries in chelonians using computedtomography. J Zoo Wildl Med 35:226-231, 2004

7. Rubel A, Kuoni W, Augustiny N: Emerging tech-niques: CT scan and MRI in reptile medicine. Semin

Avian Exotic Pet Med 3:156-160, 19948. Pees M, Kiefer I, Ludewig E, et al: Computed tomog-

raphy of the lungs of Indian pythons ( Python molu- rus ). Am J Vet Res 68:428-434, 2007

9. Valente ALS, Cuenca R, Zamora M, et al: Tomogra-phy of the vertebral column and coelomic structuresin the normal loggerhead sea turtle ( Caretta caretta ).

Vet J 174:362-370, 200710. Maisano J, Rieppel O: The skull of the Round Island

boa, Casarea dussemieri Schlegel, based on high-reso-lution x-ray computed tomography. J Morphol 268:371-384, 2007

11. Spaulding K, Loomis MR: Principles and applica-tions of computed tomography and magnetic reso-nance imaging in zoo and wildlife medicine, inFowler ME, Miller RE (eds): Zoo and Wild AnimalMedicine: Current Therapy 4. Philadelphia, W.B.Saunders Co, 1999, pp 83-88

12. Suedmeyer W, Bryan J, Johnson G, et al: Diagnosisand clinical management of multiple chromatopho-romas in an eastern yellowbelly racer ( Coluber constrictor aviventris ). J Zoo Wildl Med 38:127-130, 2007

Figure 11. CT images of a bottlenosed dolphin (Tursiops truncatus ) presented for necropsy with severe head trauma, scanned at 130kV, 83 mA, 5.0-mm slice thickness, and 1.9 sec. (A) Left anterolateral view of a 3-dimensional bone-surface–rendered image of theskull. (B) Posterior-anterior view of a 3-dimensional bone-surface–rendered image of the skull looking into the cranium. Leftanterolateral (C) and anteroposterior (D) views of a 3-dimensional volume rendition of the skull demonstrating severe soft tissue traumato the left temple.

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13. AVMA U.S. PetOwnership & Demographics Sourcebook.Schlaumburg, Illinois, Center for Information Manage-ment, American Veterinary Medical Association, 2002

14. Harcourt-Brown FM: The progressive syndrome of acquired dental disease in rabbits. J Exotic Pet Med16:146-157, 2007

15. Crossley D: Clinical aspects of lagamorph dentalanatomy: the rabbit ( Oryctolagus cuniculus ). J Vet

Dent 12:137-140, 199516. Crossley D: Oral biology and disorders of lagomorphs. Vet Clin North Am Exotic Anim Pract 6:629-659, 2003

17. Harcourt-Brown FM: A review of clinical conditionsin pet rabbits associated with their teeth. Vet Rec137:341-346, 1995

18. Souza MJ, Greenacre CB, Avenell JS, et al: Diagnos-ing a tooth root abscess in a guinea pig ( Cavia por- cellus ) using micro computed tomography imaging. JExotic Pet Med 15:274-277, 2006

19. de Voe RS, Greenacre CB, Pack L: Radiographic andCT imaging of a skull associated osteoma. Vet RadiolUltrasound 43:346-348, 2002

20. Graham JE, Kent M, Theon A: Current therapies inexotic animal oncology. Vet Clin North Am Exotic

Anim Pract 7:757-781, 200421. Antinoff N, Hahn K: Ferret oncology: diseases, diag-

nostics, and therapeutics. Vet Clin North Am Exotic Anim Pract 7:579-625, 2004

22. Krautwald-Junghanns M, Kostka V: Comparativestudies on the diagnostic value of conventional radi-ography and computed tomography in evaluatingthe heads of psittacine and raptorial birds. J AvianMed Surg 12:149-157, 1998

23. Gumpenberger M, Kolm G: Ultrasonic and com-puted tomographic examinations of the avian eye:physiologic appearance, pathologic ndings, andcomparative biometric measurement. Vet Radiol Ul-trasound 47:492-502, 2006

24. Graham JE, Werner JA, Lowenstine LJ, et al: Peri-orbital liposarcoma in an African grey parrot (Psittacus erithacus ). J Avian Med Surg 17:147-153,2003

25. Krautwald-Junghanns M-E, Schumacher F, TellhelmB: Evaluation of the lower respiratory tract inpsittacines using radiology and computed tomogra-phy. Vet Radiol Ultrasound 34:382-390, 1993

26. Gamble KC: Internal anatomy of the hornbill casquedescribed by radiography, contrast radiography, andcomputed tomography. J Avian Med Surg 21:38-49,2007

27. Posso S, Donatelli R: Skull and mandible formationin the cuckoo (Aves, Cuculidae): contributions to thenomenclature in avian osteology and systematics. Eur

J Morphol 42:163-172, 2005


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Clinical Technique Application of Computed Tomography in Zoological Medicine