Abstract
Each captive-maintained animal taxon has experienced a development phase of veterinary medicine. Invertebrates comprise a sizeable and valuable part of many zoos and aquaria and are commonly kept as pets, educational animals, and research specimens.2,5 Diagnostic imaging presents a non-invasive, economically reasonable approach to understanding anatomy and diagnosing disease in any species, including invertebrates,1,3,4 although information pertaining to appropriate radiographic technique is scarce to nonexistent. Technique charts were established for common captive terrestrial invertebrates to include a representative omnivore (Madagascar hissing cockroach, Gromphadorhina portentosa), herbivore (millipede, Orthoporus sp.), and carnivore (Chilean rosehair tarantula, Grammostola spatulata). To limit unnecessary handling of specimens, whole body weight replaced linear measurements to optimize technique. Species, gender when known, body weight, radiographic film and screen types, and technique (kVp, mAs) were recorded (Table 1). Following survey radiography, contrast radiographs were obtained. Subjects were administered contrast media orally in a food item. Radiographs were taken at intervals until contrast agent was entirely voided to document gastrointestinal transit times.
Table 1. Whole body radiographic technique charta for the Madagascar hissing cockroach (Gromphadorhina portentosa), average body weight 6.5 g
|
Film focal distance
|
MAS
|
kVp
|
Technique as compared to optimum
|
|
24
|
1
|
40
|
Underexposed
|
|
24
|
2
|
45
|
Slightly underexposed
|
|
24
|
3
|
45
|
Overexposed
|
|
24
|
4
|
40
|
Slightly overexposed
|
|
28
|
4
|
40
|
Slightly underexposed
|
|
32
|
1
|
40
|
Underexposed
|
|
40
|
4
|
40
|
Very underexposed
|
|
40
|
6
|
40
|
Underexposed
|
|
40
|
8
|
40
|
Optimum: used for contrast studiesb
|
aRadiographic views were obtained using a non-grid technique (TREX TM40, TREX Medical Corporation, Broadview, Illinois 60153 USA, and 3M Veterinary Radiographic film, Uultra 2000, green sensitive film, 3M Animal Health Care Products, St. Paul, Minnesota 55144 USA).
bBarium sulfate suspension (Liquid E-Z-Paque, E-Z-EM, Inc., Westbury, NY 11590 USA) and diatrizoate meglumine and diatrizoate sodium (Hypaque-76, Amersham Health Inc., Princeton, NJ 08540, USA) were both imaged in a food item (mashed banana), following ingestion at 30 min, and 4 h after ingestion. Although no radiographic difference was observed between the food items containing each of the contrast agents, better consumption of the food item containing Hypaque-76 was noted.
Literature Cited
1. Bock, C., M. Frederich, R.M. Wittig, and H.O. Portner. 2001. Simultaneous observations of haemolymph flow and ventilation in marine spider crabs at different temperatures: a flow weighted MRI study. Magn. Resonance Imaging 19(8):1113–1124.
2. Cooper, J.E. 1996. Hoppers, hermits and haemolymph: a veterinary approach to invertebrates. Proc. Am. Assoc. Zoo Vet. Annu. Meet. Pp. 280–285.
3. Schofield, J.C., R.M. Grindley, and J.A. Keogh. 2001. The use of diagnostic radiology to detect shell irregularities in the New Zealand paua (abalone) Haliotis iris. Lab. Anim. 35:167–171.
4. Wheeler, S., T. Hornschemeyer, and M. Hocha. 2002. Investigation of insect morphology by magnetic resonance imaging. Magn. Resonance Imaging 20(1):105–111.
5. Wolff, P.L. 1993. Achy breaky arachnids. Proc. Am. Assoc. Zoo Vet. Annu. Meet. Pp. 127–133.