No abstract

No abstract

From 11 North American veterinary university hospitals and clinics, 248 animals were a confirmed diagnosis of nervous-tissue tumor were identified; 7 tumors were found in cattle, 28 in horses, 14 in cats, 199 in dogs, and none in other species. Tumors were divided for analysis into three categories-glial, meningeal, and peripheral nerve. In cattle and horses, all tumors involved peripheral nerves, the risk of which, in horses, reached a plateau at 4-6 years of age and remained constant thereafter. In cats, the tumors were equally distributed among the three tumor categories whereas, in dogs, twice as many glial tumors as meningeal and peripheral nerve tumors were found. The risk for glial tumors in dogs reached a peak at 10-14 years of age, for meningeal at 7-9 years, and for peripheral nerve at 2-3 and 7-9 years. Three canine breeds-English bulldog, boxer, and Boston terrier-had an excessive rish of glial tumors. Except for an excess of skin tumors in dogs with peripheral nerve tumors, there was no unusual occurrence with second primary neoplasms for any species. There was no detectable predisposition by sex for any of the categories of nervous-tissue tumors among any of the four species. The role of genetic abnormalities associated with nervous-tissue tumors and other etiologic factors (e.g., chronic hypoxia) may be clarified by further studies involving canine breeds of "bulldog" ancestry.

Of 2075 mammary neoplasms in bitches reported by 14 veterinary schools in the United States and Canada, 1187 were histologically malignant, 557 were benign, and 331 were in the ‘malignancy not determined’ category. There were 12 breeds at significantly high risk for one or more of the major mammary tumour types; 7 of the 12 were hunting breeds. Mixed breeds were at low risk for all tumour types and categories, and collies were at low risk for benign neoplasms. Neutered bitches were only one‐third as likely to have neoplasms as were entire bitches. There was no clear difference in distribution of the various tumour types in relation to age at first diagnosis. Among the four geographical regions studied separately, there were more similarities than differences in the rates of mammary neoplasms, especially when adenocarcinomas and malignant mixed mammary tumours were combined for analyses. There was, however, a marked excess of benign neoplasms in the south and west of North America.