Rabbit skull radiology
Corby Holson and David
Martinez-Jimenez
|
Introduction to
rabbit radiology Radiology in the
domestic rabbit (Oryctolagus cuniculus) can be challenging due to
their size, and easily stressed nature. Small mammal radiology requires a
basic knowledge of anatomy and physiologic characteristics. Therefore, three
important factors require further attention when taking radiographs in rabbits: 1.
Rabbits are prey
species and therefore, they become extremely agitated when exposed to
unfamiliar situations. Manual restraint can be difficult, and dangerous, for
any length of time. Sedation or anesthesia is usually required. 2.
The relatively small
size of rabbits has the advantage of allowing whole-body radiographs and
quick examination of the entire patient. However, it may result in a loss of
detail due to the differences in size between different body areas. 3.
Motion of the object
during the imaging sequence generally results in a blurring. Because motion
artifact is a common problem in rabbits, the minimum requirement for x-ray
equipment is the capacity to produce 300 mA in 1/120 (0.008) second. Settings and
equipment The x-ray machine
should be capable of working with 5.0 to 7.5 mAs exposures, and have a range
of 40 to 100 KVp, which is adjusted in 1 to 2 KVp increments. Often when
radiographing rabbits, mammography films and cassettes are utilized (Mamoray®
cassette, Mamoray HDS, AGFA Corporation, Greenville, SC). This system
provides ultra fine detail in smaller species. Positioning Radiography in
rabbits, and other small mammals, can be challenging as they are highly
stressful, resistant to restraint and have a small body size in relation to
their short extremities. Visual anatomic landmarks are preferred over
palpated anatomic landmarks because their thick subcutaneous adipose layers
and dense hair coats make it difficult to palpate accurately. Correct
symmetry and stabilization of the patient can be accomplished by using
radiolucent materials such as foam and tape for support. Skull radiography Rabbit bones are
delicate in comparison to that of other domestic companion animals. For
example, the skeleton of a rabbit represents only 7-8% of body weight but is
12-13% of body weight in a cat. Paradoxically, the muscles of rabbits are
extremely strong and powerful which can lead to fractures or luxations if
held improperly. Skull radiography
can provide useful information about the nares, sinuses, middle ears, teeth
and surrounding bone. Radiographic views should include lateral and
dorsoventral views, as well as obliques when necessary (e.g. dental disease
evaluation). Oblique radiographs projections require rotations at 30 degrees
angles (described by the point of entrance of the x-ray beam to the point of
exit). Magnification radiography is commonly used in exotic
patients when higher definition, detailed images are necessitated. It
requires the use of an ultra-small focal spot x-ray tube and an increased
object-film distance as compared to standard radiographs.
Pathological radiography
associated to the rabbit skull Skull
radiography is an extremely valuable tool in rabbit medicine, not only
because it helps localize and diagnosis specific anatomical disease, but it
also serves as an important prognostic determinant. For instance, an
increased density in tympanic bullae, nares, or sinuses may indicate infection. On the other
hand, decreased density may occur in advanced cases of infection or
neoplasia.
Degree
of dental disease and prognosis can be also determined by radiographic
evaluation. Facial abscesses and osteomyelitis of the maxilla or mandible in
lagomorphs are often related to dental disease and bacterial infection. The
precise etiology of dental disease in the pet rabbit is still unknown and is
likely to be multifactorial including primary (inherit) and secondary causes
(diet, metabolic, traumatic and infectious components).
Radiography
is an essential diagnostic tool that can help localize both bone and soft
tissue lesions before attempting surgical correction. Radiographs can also
accurately grade dental disease from 1 (normal) to 5 (severe dental disease,
including oral abscesses). Conclusion Radiology
is an essential tool for any practitioner working with rabbits. Due to their
stressful temperament and keen ability to hide disease, thorough and careful
examination including radiographs is warranted. Rabbits are particularly
predisposed to dental disease, and skull radiographs can detect lesions
unlikely to be observed during physical examination. Radiographs also serve
as an important tool for grading dental disease and are valuable in providing
accurate prognosis to clients. References Harcourt-Brown, F. M. (1997).
"Diagnosis, treatment and prognosis of dental disease in pet
rabbits." In Practice 19: 407-421. Lobprise, H. B. and R. B. Wiggs
(1991). "Dental and oral disease in Lagomorphs." J Vet Dent 8(2):
11-7. Silverman, S. and L. A. Tell (2005).
“Radiology equipment and positioning techniques”. In: Radiology of rodents,
rabbits, and ferrets: an atlas of normal anatomy and positioning.
Elsevier Saunders, St Louis. Pp. 1-8. Stefanacci, J. D. and H. L. Hoefer
(2004). “Radiology and ultrasound”. In Ferrets, rabbits, and rodents.
Clinical medicine and surgery.” Second edition. K. Quesenberry and J.
W. Carpenter (Eds.). Elsevier Saunders, St. Louis. Pp. 395-396. Acknowledgement The authors would like to thank Dr. Hernandez-Divers and Dr.
Wilson for their help and support, as well as for some of the pictures
provided. |
e-mail: info@medirabbit.com
