Today’s Veterinary Practice November/December 201462

ImagIng EssEnTIals PEER REVIEWED

Radiography of reptile patients is routinely used for evalu-ation of traumatic injuries and the gastrointestinal and reproductive tracts.

A reptile radiography study typically includes lateral and dorsoventral views. Additional collimated views of areas of interest are obtained in specific species. For example, in turtles and tortoises, a craniocaudal view is added to complete the study.

Unlike dogs or cats, whole-body radio-graphs are taken of reptiles in order to visualize the entire coelomic cavity. In addition, horizontal beam radiographs of reptiles other than snakes (turtles and tortoises) are important for visu-alization of the dorsal coelomic struc-tures (lungs).

Imaging Essentials provides comprehensive information on small animal radiography techniques, and the series has addressed the majority of anatomic areas in canine and feline patients, including the head and spine, thorax and abdomen, and the limbs and joints. avian radiography was most recently covered in our september/October 2014 issue. access these articles through our online Article Library, available at tvpjournal.com.

danielle Mauragis, CVt, and Clifford R. Berry, dVM, diplomate aCVRUniversity of Florida

REPTILE RADIOGRAPHY

November/December 2014 Today’s Veterinary Practice 63

ImagIng EssEnTIals |

Re

pt

ile

Ra

dio

gR

ap

hy

tvpjournal.com

POSITIONINGAnesthesia/SedationThe reptile patient can undergo radiography awake, but general anesthesia is sometimes required to ensure good-quality posi-tioning. Conscious turtles and tortoises have the ability to hold their extremities and head within or close to their shells. In the instance of fracture, sedation or anesthesia may be needed to relax the neck or extremity and isolate it, avoiding superimposi-tion with the shell, for complete evaluation.

Restraint TechniquesFor whole-body studies, conscious turtles or tortoises can some-times be restrained by taping the limbs to or inside the shell (Figure 1): 1. Tape a figure-8 pattern with 2-inch porous tape over the tho-

racic and pelvic limbs. 2. Start with the carapace or plastron and tape over a thoracic

limb, followed by the opposite pelvic limb, then back to the same thoracic limb.

3. Cross over the shell to the contralateral pelvic limb and then the contralateral thoracic limb, and continue in a figure 8 pat-tern for at least a second time. To tape the head inside the carapace, place a piece of 2-inch

porous tape from the carapace down over the head and secure

B

A

Figure 2. Tortoise placed in radiolucent tub for a laterally positioned, horizontal-beam radiograph (A) and corresponding radiograph (B). Snake positioned in a tube for either lateral or dorsoventral radiographs (C).

C

Figure 1. Figure-8 taping of a tortoise; cranial view.

to the plastron.To prevent the patient from moving

forward:• Place a sponge anchored with a sandbag

in front of the nose of a lizard, turtle, or tortoise

• Place a chelonian in a radiolucent plastic tub (Figure 2).

•Use a similar tub for a snake in order to keep the entire snake spread out for a dorsoventral projection; a tube can be used to keep the snake straight for lat-eral or dorsoventral projections.

ProjectionsDue to the nature of the coelomic cavity, use horizontal-beam or cross-table projec-tions, if possible, for the lateral and cranio-caudal projections of turtles and tortoises. In other reptile species, vertical-beam dor-soventral projections are also acceptable.

RADIOGRAPHIC EXPOSURETechnique and exposure depend on the size of reptile. •Use an abdominal technique due to the

variable opacities of the coelomic cavity. •A grid is recommended for patients with

depth greater than: » 10 cm (film/screen) » 15 cm (digital radiography).

•Measure each projection and use appro-priate technique as indicated by the technique chart.

| ImagIng EssEnTIals

Today’s Veterinary Practice November/December 201464 tvpjournal.com

• If using a horizontal-beam method, remem-ber to adjust technique when not using the grid: decrease the mAs by 1/3 if the original technique was set with an 8:1 grid.

DORSOVENTRAL PROJECTION1. Place the patient in ventral (sternal) recum-

bency directly on the: » Cassette for a tabletop technique » X-ray table for a film tray technique.

2. Ensure collimation includes the entire shell or body of the reptile—the skull and extremities in addition to the coelomic cav-ity (Figure 3).

B

A

Figure 3. Tortoise positioned in sternal recum-bency for dorsoventral projection (A) and cor-responding radiograph (B). Presence of metal plates and screws are result of shell fracture repair after the tortoise was hit by a car.

Figure 4. Tortoise elevated off the x-ray table for horizontal-beam lateral projection (A) and corresponding radiograph (B).

LATERAL PROJECTIONPositioningPlace the patient in right lateral recumbency; however, in the instance of trauma or pathologic abnormality, place the affected side closest to the cassette.

Horizontal-Beam or Cross-Table Technique (Figure 4)If possible, use a horizontal-beam or cross-table for the lateral projection.1. Rotate the x-ray tube head 90° toward the patient. 2. Place the cassette or detector on the right side of the

patient—or the affected side—and secure it in place with a cassette holder or sandbag.

3. Elevate the patient off the x-ray table, which places the patient as close to the middle of the cassette or detector as possible, by using radiolucent sponges, positioning troughs, or boxes.

4. Center the x-ray beam at midbody of the patient and ensure collimation includes the entire shell or body.

A

B

November/December 2014 Today’s Veterinary Practice 65

ImagIng EssEnTIals |

Re

pt

ile

Ra

dio

gR

ap

hy

tvpjournal.com

Tabletop or Film Tray Technique (Figure 5)If a horizontal beam is not available: 1. Place the patient in lateral recum-

bency directly on the: » Cassette for a tabletop technique » X-ray table for a film tray tech-nique.

2. Prop turtles and tortoises in lat-eral recumbency by using a posi-tioning trough or sponges.

3. Ensure collimation includes the entire shell or body of the reptile.

CRANIOCAUDAL PROJECTION (TURTLES/TORTOISES) The craniocaudal projection of the turtle or tortoise is used to visual-ize the left and right sides of the lungs.

Horizontal-Beam or Cross-Table Technique (Figure 6)If possible, use a horizontal-beam or cross-table for this projection.1. Rotate the x-ray tube head 90°

toward the patient. 2. Place the cassette or detector

behind the patient and secure it in place with a cassette holder or sandbag.

3. Elevate the patient off the x-ray table, which places the patient as close to the middle of the cassette or detector as possible, by using radiolucent sponges, positioning troughs, or boxes.

4. Center the x-ray beam in front of the patient’s head—the patient will be looking at the collimator.

5. Ensure collimation includes the left and right sides of the shell. The left and right hemisphere should appear equal, with the spine superimposed.

Tabletop or Film Tray Technique (Figure 7, page 66)If a horizontal beam is not available: 1. Place the patient in a cranial to

caudal direction directly on the: » Cassette for a tabletop technique » X-ray table for a film tray tech-nique.

2. Ensure collimation includes the entire shell or body of the turtle/tortoise.

Figure 6. Horizontal-beam craniocaudal radiograph of tortoise; comparison of the radiographs in Figures 6 and 7 (page 66) demonstrates that horizontal-beam imaging clearly depicts the lungs without superimposition of the coelomic contents.

Figure 5. Tortoise placed in positioning trough for vertical-beam lateral projection (A) and corresponding radiograph (B); this approach is used if horizontal-beam radiographs cannot be obtained. Comparison of the radiographs in Figures 4 and 5 demonstrates that horizontal-beam imaging clearly depicts the lungs without superimposition of the coelomic contents.

B

A

| ImagIng EssEnTIals

Today’s Veterinary Practice November/December 201466 tvpjournal.com

Suggested ReadingHan CM, Hurd CD. Practical Diagnostic Imaging for the

Veterinary Technician, 3rd ed. Philadelphia: Elsevier, 2004.Lavin LM. Radiography in Veterinary Technology, 5th ed.

Philadelphia: Elsevier, 2013.Thrall DE (ed). Textbook of Veterinary Radiology, 6th ed.

Philadelphia: Saunders Elsevier, 2012.

A

Figure 7. Tortoise placed in positioning trough for vertical-beam craniocaudal projection (A) and corresponding radiograph (B); this approach can be used if horizontal-beam radiographs cannot be obtained.

B

Figure 8. Dorsoventral cranial radiograph of a monitor lizard: Two projections are required to image the entire body of this lizard. In some snakes, more than 2 radiographs are required, with the patient in lateral recumbency.

Danielle Mauragis, CVT, is a radiology technician at University of Florida College of Veterinary Medicine where she teaches diagnostic imag-ing. She coauthored the Handbook of Radiographic Positioning for Veterinary Technicians and received the Florida

Veterinary Medical Association’s 2011 Certified Veterinary Technician of the Year Award.

Clifford R. Berry, DVM, Diplomate ACVR, is a professor in diagnostic imaging at University of Florida College of Veterinary Medicine. His research interests include cross-sectional imag-ing of the thorax, nuclear medicine, and biomedical applications of imag-

ing. He received his DVM from University of Florida and completed a radiology residency at University of California–Davis.

IMAGE QUALITYFor quality control of any diagnostic image, follow a simple 3-step approach:1. Use the appropriate technique (appropriate expo-

sure and development factors).2. Obtain the entire anatomic region of interest in the

image. In larger reptiles, sequential cranial to caudal radiographs with the patient in lateral or sternal recumbency ensures complete evaluation.

3. Make sure the anatomic region is positioned appro-priately with regard to centering, alignment, and symmetry. Symmetry, especially for musculoskeletal structures, is key to proper evaluation because it assists the interpreter, especially with regard to ana-tomic differences between species.For the coelomic cavity, all projections—dorso-

ventral, lateral, and craniocaudal (turtle/tortoise)—should include as much of the patient as possible. For other lizards or snakes, the tail or other portions of the coelom will need to be radiographed separately (Figure 8). n

November/December 2014 Today’s Veterinary Practice 67tvpjournal.com

PRaCTICal TECHnIQUEs |

•Treat the incision with cold pack therapy, 10 minutes Q 6 H, for 2 to 3 treatments.

Care & Follow-UpPatients are typically kept in the hospital overnight and discharged the day after surgery. Postoperative activity is limited to strict crate rest for 8 weeks after surgery. Post-surgery recheck examinations are performed at 2, 6, and 12 weeks.

IN SUMMARY Patellar luxation can cause clinically significant hindlimb lameness in cats. Patients with persistent lameness attribut-able to patellar luxation should be considered candidates for surgical therapy.

Surgical treatment of patellar luxation is typically a mul-tistep process. The exact techniques required vary from patient to patient. The final decision about which surgical techniques to use in a particular patient is based on intra-operative assessment of patellar tracking in the trochlear groove.

Use of sound decision making and intraoperative atten-tion to detail lead to consistently successful surgical cor-rection of feline patellar luxation. n

References1. Smith GK, Langenbach A, Green PA, et al. Evaluation of the association

between medial patellar luxation and hip dysplasia in cats. JAVMA 1999; 215(1):40-45.

2. Scott HW, McLaughlin R. Feline Orthopedics. London: Manson Publishing

Ltd, 2007, pp 218-222.3. Johnson ME. Feline patellar luxation: A retrospective case study. JAAHA

1986; 22:835-838.4. Loughin CA, Kerwin SC, Hosgood G, et al. Clinical signs and results of

treatment in cats with patellar luxation: 42 cases (1992-2002). JAVMA 2006; 228(9):1370-1375.

5. Putnam RW. Master’s thesis: Patellar luxation in the dog. Ontario, Canada: University of Guelph, 1968.

6. Singleton WB. The surgical correction of stifle deformities in the dog. J Small Anim Pract 1969; 10(2):59-69.

7. Kowaleski MP, Boudrieau RJ, Pozzi A. Stifle joint. In Tobias KM, Johnston SA (eds): Veterinary Surgery: Small Animal. St. Louis: Elsevier, 2012, pp 906-998.

8. Piermattei DL, Johnson KA. An Atlas of Surgical Approaches to the Bones and Joints of the Dog and Cat, 4th ed. Philadelphia: Elsevier Saunders, 2004, pp 342-349.

9. Talcott KW, Goring RL, de Haan JJ. Rectangular recession trochleoplasty for treatment of patellar luxation in dogs and cats. Vet Compar Orthop Traumatol 2000; 13:39-43.

10. Piermattei DL, Flo GL, DeCamp CE. Handbook of Small Animal Orthopedics and Fracture Repair, 4th ed. St. Louis: Saunders, 2006, pp 562-632.

Caleb Hudson, DVM, MS, Diplomate ACVS, is a surgeon at Gulf Coast Veterinary Specialists in Houston, Texas. His special interests include total joint replacement and minimally invasive surgery. Dr. Hudson received his DVM from University of Missouri, and

completed a rotating internship in small animal medicine and surgery, residency in small animal surgery, and MS in veterinary science from University of Florida.

(Practical Techniques: Surgery continued from page 37)