Small mammals can be rewarding to work with, although they can also present some unique challenges.
When radiographing these pets, it’s important to understand species differences and plan accordingly.
Here are some tips and starting points for radiographing these unique pets…
Considerations for Small Mammal X-Ray Studies
While often lumped together as one group—commonly called “small mammals,” “exotic small mammals,” or even “pocket pets” for smaller species—this group of pets actually covers a range of diverse species.
This can include everything from ferrets to guinea pigs and rabbits to small rodents like hamsters and mice—and even marsupials like sugar gliders.
It’s important to understand what’s normal and what’s not for each species. For example, hindgut fermenters (rabbits, guinea pigs, and chinchillas) often have notable gas in their GI tract, whereas that amount of gas would be abnormal for a ferret.
To gain an understanding as to what’s normal for each species, it helps to not only study texts and references but also to practice looking at radiographs of healthy pets for comparison.
In addition to understanding species differences in anatomy, it’s also important to consider each patient’s needs when preparing for an x-ray study. For example, certain small mammals may face health consequences with fasting prior to x-rays. For others, a short period of fasting (especially if anesthesia is used) might be appropriate.
Due to the small size of most patients, highly detailed images are needed. Many experts recommend using mammography films for this reason, with tabletop technique. For very small patients, or for extremity views, dental x-ray machines and films may provide good results.
Positioning and Restraint of Small Mammals
Since many small mammals are prey species, they may be prone to excess stress with strong manual restraint, especially if they are already ill. For critical, dyspneic, and otherwise in poor condition patients, it’s usually best to stabilize them prior to pursuing diagnostics.
For patients who are stable, it may make sense to use manual restraint for short studies. Chemical restraint is often favored over manual restraint, though, for reducing patient stress and patient movement. Chemical restraint may include injectable sedative drugs, or inhalant anesthetic delivered via intubation. If intubation isn’t possible, inhalant delivery via mask may also be an option for some patients. Check for appropriate drug doses for each species.
The use of positioning aids and props depends on the size of the patient. Due to their small size, heavy sandbags are not typically used for these patients. Taping a patient’s limbs to the cassette may be a better strategy. And a small trough may be helpful for obtaining a VD view.
Key Radiographic Views
As with any other species, it’s important to obtain a minimum of two orthogonal views (a lateral and VD/DV) with proper patient positioning. Then, additional views such as obliques can be added if relevant.
Because most of these patients are small in size, whole-body radiographs are common. Then, additional close-up views of areas of interest (like limbs or the skull, for example) can be included, too. For patients who are large enough, it may be ideal to do separate thoracic and abdominal studies.
If needed, standard contrast agents such as barium and iodinated contrasts may be used. Keep in mind that GI transit time is variable depending on the species. In general, carnivores (like ferrets) have the fastest transit times, while hindgut fermenters have the slowest.
Skull radiographs are common in small mammals for evaluating dental issues. A complete set of skull radiographs usually includes DV/VD, lateral, right and left oblique, and “skyline” (rostrocaudal) views.
Conclusion
With the right knowledge, practice, and a few adaptations, radiographs can be used to help diagnose and treat small mammals. Owners of these unique pets often appreciate finding a veterinarian who is able to perform such procedures and deliver a high quality of care to these small patients.
Written by: Dr. Tammy Powell, DVM