Mammary tumors are frequent in dogs, and they correspond to 25% of the neoplasms in this species8. The variety of histological types has produced conflicting concepts related to classification and histogenesis, what resulted in a variety of taxonomic systems.
Mammary neoplasms in dogs that are similar to those in humans16,20,22 are of special concern to the oncology researchers because they may be used as biological models in the search for more precocious diagnoses, more exact prognoses and a more efficient therapeutic procedures.
In the present trial, 1,371 cases of alterations in the mammary glands of dogs were analyzed and 578 specimens were studied. These cases are part of the records in FMVZ / USP from 1936, when the school was founded, to 1999. Classification used was that of the World Health Organization (WHO), adapted by Hampe and Misdorp7 , which is based on descriptive morphology and histogenesis. Neoplasms were described as complex when secretory and myoepithelial cells were altered. They were described as simple when only one of the cell types was modified. Both simple and complex carcinomas were classified according to the level of differentiation of the tubules. Tubular adenocarcinomas are placed at one of the extremes, and anaplastic carcinomas, at the other.
Mammary neoplasms frequently present abundant extracellular matrix (ECM), called desmoplasia8. In dogs, it is common to observe cartilaginous and bone metaplasia8.
The objective of the present trial was to reclassify benign and malignant neoplasms in dogs, according to the WHO guidelines, in order to determine the number of cases as well as the frequency of desmoplasia and cartilaginous and bone metaplasia in the specimens analyzed.
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