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 ACVR

University of Florida

rePtile radiograPhy

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POSITIONING

Anesthesia/Sedation

The 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 Techniques

For 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.

Projections

Due 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 EXPOSURE

Technique 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.

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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 PROJECTION

1. 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 PROJECTION

Positioning

Place 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

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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

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

Suggested Reading

han 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 QUALITY

For 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-Up

Patients 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

References

1. 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.

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(Practical Techniques: Surgery continued from page 37)