Radiographic studies of the guinea pig can usually be carried out without sedation, although brief gaseous anaesthesia with direct induction may be administered. Given the size of the guinea pig, lateral and ventrodorsal views of the whole body should be performed routinely unless the animal is severely debilitated and stressful manipulation could precipitate a cardiorespiratory crisis. If necessary, a dorsoventral X-ray may be performed since this can provide useful information without having to subject the animal to stressful manoeuvres. Images of the perineum should also be taken, because urethral stones may be present.
X-rays of the skull should be taken in order to evaluate the animal’s dentition.
X-RAYS OF THE SKULL
The occlusal surface is not visible in lateral views with a closed mouth because of the slant of the surface. Evidence of a flat occlusal surface in a lateral view is an indicator of malocclusion.
The apices of the mandibular molariform teeth are very close to the ventral cortex of the mandible; they can be best seen in a slightly oblique projection (about 10°). In the case of malocclusion there is prolongation of the apices with deformation of the inferior border of the mandible.
It is difficult to interpret dentition from a ventrodorsal projection because the structures are superimposed; this view is, however, useful for evaluating the tympanic bullae. The rostrocaudal view, if correctly aligned, is useful for evaluating the occlusal surfaces of the molariform teeth and the temporo-mandibular joints, but is difficult to perform in a conscious animal.