This study will test the usefulness of canine intranasal tumor staging systems, plus a promising biologic marker tested on a large series of dogs treated similarly for intranasal neoplasia. The intent is to identify a system that could become the benchmark of initial evaluation for this tumor type. Biologic behavior of intranasal neoplasia (INN) in a serious of affected dogs, all treated in the same manner with radiotherapy, has been recorded in the University of Wisconsin Veterinary Medical Teaching Hospital (UMVMTH) computerized data base system. Biologic behavior findings will be compared to pretreatment assessment of severity of the disease as determined by application of 3 published and one new proposed staging systems, based on computed tomography (CT) findings. Further, biologic behaviors of INN in this series of dogs will be compared to expression of the biologic marker Ki-67, found in pretreatment biopsy samples.