Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

644 Small Animal Radiolo g y and Ultrasono graphy
extend to the retrobulbar space causing exophthalmos. This may be the clinical feature that
is first noticed by the owner.
The most common nasal tumors are adenocarcinoma, nonkeratinizing squamous cell
carcinoma, and chondrosarcoma in dogs and lymphoma in cats. 53,128,136 In cats, the presence
of soft-tissue density in only one nasal passage is most commonly associated with
lymphoma. 137 CT and MRI are superior to radiography for detecting invasion into the
cribriform plate. 138
Fig. 5-39 A 6-year-old female Cocker Spaniel with
nasal discharge for several months. The open-mouth
ventrodorsal radiograph revealed a moderate decrease
in the prominence of the intranasal bony structures,
which gives the appearance of hyperlucency. The
existing bony structures appear thickened and coarse.
Differential diagnoses include fungal rhinitis and neoplasia.
Diagnosis: Nasal aspergillosis.
Fig. 5-40 A 6-year-old Havana Brown cat with bilateral nasal
discharge for 3 weeks. The open-mouth ventrodorsal view
revealed obliteration of air passages in the left planum nasale.
There is an overall increased tissue density in the left nasal passages.
All incisive and maxillary teeth are absent except for the
second incisor. The vomer, which normally is apparent to the
level of the rostral border of the incisive bones, has been
destroyed in its most rostral aspect (black arrow). Differential
diagnoses include nasal neoplasia and infection. Diagnosis: Nasal
fibrous histiocytoma.