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Radiology of the Rabbit Thorax |
Sam Silverman, DVM, University of California/Davis, School of Veterinary Medicine
the medical and surgical care of rabbits. Following is an excerpt from Dr. Sam Silverman's radiology lecture at the HRS Veterinary Conference last March, discussing radiographic interpretation of some common clinical views of the rabbit thorax.
When thinking about a rabbit's lung capacity, I remember when I was in the mountains flying a helicopter, I'd see these tracks in the snow, rabbits running and running and doing figure eights-- a coyote or something was chasing them. I was amazed at how aerobically fit these guys must be. But when you look at their thorax, it's absolutely amazing, because there is very little aerated lung for the size of the animal.
Notice there's no retrosternal lucency of cranial lung lobes inflated with gas, and the cardiac borders are often relatively indistinct, especially if a large amount of fat is present. It is essential that the front legs be fully extended cranially on the lateral projection to obtain optimum radiographic detail of the cranial thorax. You do not see large caudal lung fields; the scapulas are superimposed on the dorsal thorax, so if you were to read this out as a dog or a cat, you would come out with a much different diagnosis than you would as a rabbit.
The Cat Thorax A cat is about the same size as a rabbit. But in a rabbit the heart is located cranially, very close to the thoracic inlet (compare a cat thorax to a rabbit thorax on the opposite page). You do not see the cranial mediastinum in the rabbit, because the heart is so far cranial. You do not see distinct bronchial markings. You do not have tremendous inflation of lungs in the normal rabbit either. You can't think of a rabbit as a ferret. You can't think of a rabbit as a guinea pig. A rabbit is a completely different species in regard to radiographic anatomy.
A frontal view is a little better, but don't forget, when we make a measurement on the chest, our technique charts are set up on the basis of soft tissue to aerated lungs. If you were to take a 10-centimeter cat and a 10-centimeter rabbit, and use the same exposures, the rabbit would be underexposed. Notice again that there is no cranial mediastinum, because the heart is located far forward.
Obese Rabbit Thorax
Bezoar in Thoracic Radiograph
Chronic Respiratory Disease
Although our ability to closely describe patterns and abnormalities in the rabbit thorax is very limited compared to our abilities in cats, radiography is still a very useful tool.
Radiographs by the Author
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