Primary tumors of the nasal cavity account for about 1% or 2% of all neoplasms in dogs.1,2 Of these neoplasms, about 80% have histologic characteristics of malignancy.1 In dogs, nasal neoplasms are regionally invasive with frequent expansile growth into the nasal passages, frontal sinuses,
and cranial vault cavity; however, documented distant metastasis to the lungs or regional draining lymph nodes is uncommon
upon initial presentation.3,4
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Carcinomas are more common than sarcomas and account for 60% to 78% of all nasal tumors in dogs.1,3-5 In five studies analyzing 711 nasal tumors in dogs, adenocarcinoma was the most common histologic subtype (45%), followed
by squamous cell carcinoma (20%), chondrosarcoma (14%), undifferentiated or anaplastic carcinoma (11%), and unspecified carcinoma
(10%).1,3,4,6,7
Nasal tumors are less commonly diagnosed in cats than in dogs but, nonetheless, behave similarly to canine nasal tumors with
regional invasion and a low metastatic rate.1 Lymphoma and carcinoma (adenocarcinoma, squamous cell carcinoma) are the most common types of nasal tumor diagnosed in cats.1,8-10
Other less frequently diagnosed nasal malignancies that have been reported in dogs and cats include fibrosarcoma, mast cell
tumor, transmissible venereal tumor, hemangiosarcoma, neuroendocrine carcinoma (olfactory neuroblastoma), peripheral nerve
sheath tumor, fibrous histiocytoma, rhabdomyosarcoma, leiomyosarcoma, and melanoma.1,3,4 Benign tumors may also arise from the nasal cavity, including nasal polyps and fibromas, but they are not discussed in this
review article.
SIGNALMENT
Age
Similar to other neoplastic conditions that predominantly arise in the geriatric population, nasal tumors most commonly affect
middle-aged to older dogs and cats. The average age of onset for nasal carcinomas is reported to be 9 or 10 years, while the
development of nasal sarcomas is reported to occur in slightly younger animals (7 or 8 years old).3,4,9,11-16
Breed
Although nasal tumors may be diagnosed in any dog breed, dolichocephalic and mesocephalic breeds are considered to be at an
increased risk for developing nasal tumors.15-18 One potential hypothesis for this observed breed predilection is that the greater nasal passage surface area in dolichocephalic
and mesocephalic dogs predisposes them to greater exposure to inhaled carcinogens and subsequent tumor development. In addition,
the larger nasal surface area would be associated with a greater number of nasal epithelial cells, which could be malignantly
transformed after exposure to inhaled carcinogens.
Sex
Reports vary on whether there is a male sex predilection for nasal tumors in dogs. As such, it is unlikely that the development
of nasal tumors is under hormonal influence. Contrary to dogs, male cats have been reported to have about a twofold increased
risk for developing nasal tumors, although an underlying mechanism to explain this observation has yet to be postulated.1
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