Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Five The Skull 643
Fig. 5-38 An 11-year-old male mixed breed dog with exudate
from the right nostril for 3 weeks. A, The open-mouth ventrodorsal
view revealed a homogeneous tissue density involving
the caudal one-half of the right nasal passage. The vomer was
intact and no evidence of bony destruction was present. The areas
of the right frontal sinuses that are not superimposed over the
nasal passages (black f) also revealed tissue density compared with
the left side (white f). B, The frontal sinus view revealed the tissue
density in the right frontal sinus (black f) compared with the normal
left side (white f). Differential diagnoses include rhinitis and
sinusitis or neoplasia. Diagnosis: Rhinitis and sinusitis of the
right nasal passages and sinuses.
A
B
Destructive (fungal) rhinitis may also cause destruction of the vomer; however, when a
tumor is present the tissue density within the nasal cavity will be contiguous at the site of
vomer destruction. In destructive rhinitis, the erosion or deviation of the vomer may be
present without an adjacent soft-tissue density or mass. Erosion or destruction of the cribriform
plate or frontal bones suggests a probable diagnosis of nasal adenocarcinoma with
extension of tumor into the cranial vault (Fig. 5-41). Detecting the erosion may be difficult
unless it is extensive. Computed or linear tomography and MRI are more sensitive in
detecting small erosions, and these studies can be performed in addition to the radiographs
if extension of the tumor into the cranial vault is suspected. Affected animals may have
seizures or other primary neurologic signs rather than showing signs of nasal disease. 126
Nasal tumors may penetrate the nasal and maxillary bones also, resulting in a mass dorsal
to the nasal passages (Fig. 5-42). In some cases, the tumor may penetrate the maxilla and