Canine mammary gland tumours; a histological continuum from benign to malignant; clinical and histopathological evidence^*

Abstract

This study describes the clinical and histopathological findings in dogs with mammary gland tumours, and compares the histopathological and clinical evidence consistent with progression from benign to malignant to human breast cancer epidemiology. Clinical and histopathological data on 90 female dogs with 236 tumours was included. Dogs with malignant tumours were significantly older than dogs with benign tumours (9.5 versus 8.5 years), P = 0.009. Malignant tumours were significantly larger than benign tumours (4.7 versus 2.1 cm), P = 0.0002. Sixty-six percent had more than one tumour, and evidence of histological progression was noted with increasing tumour size. Dogs with malignant tumours were significantly more likely to develop new primary tumours than dogs with benign tumours, P = 0.015. These findings suggest that canine mammary tumours progress from benign to malignant; malignant tumours may be the end stage of a histological continuum with clinical and histopathological similarities to human breast carcinogenesis.

Immunohistochemical detection of tumour cell proliferation and intratumoural microvessel density in canine malignant mammary tumours

“…In the present study, the average age was 9.5 years (ranging from 4 to15 years) in dogs with malignant tumours, which was similar to that reported in previous studies (2,27).…”

Immunohistochemical and molecular analysis of caveolin-1 expression in canine mammary tumors

“…The dogs ranged from age 2 to 17 years (mean 10 years) and most were of mixed breeds. According to Sorenmo et al (2009) andFerreira et al (2009) models, the staging tests included routine bloodwork (complete blood count, serum chemistry profile), urinalysis, fine needle aspirates of palpable draining lymph nodes, and thoracic radiological examinations. The mammary glands were examined carefully and all tumors were recorded and measured.…”

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“…Our results indicate that this process also likely occurs in female dogs and that similar studies on the biological behavior of these lesions should be performed in canines. A recent, predominantly epidemiologic report that included clinical and histopathologic data from 90 female canines with 296 tumors hypothesized those malignant mammary tumors could develop from pre-existing low-risk IELs and that the malignant tumors would be the final stage [77]. Although the authors of the report described the very beginning, as also reported for women by Man, et al [20].…”

“…The detection of early lesions in MG has demonstrated its importance for preventing and diminishing the mor-that within the same MG there is substantial heterogeneity and that the benign and malignant lesions are multifocal and have variable size, they did not interpret the meaning of these findings. Similarly, Mouser [17] and Sorenmo [77] also reported the multifocality and simultaneous or asynchronous character of IELs and mammary tumors but did not offer any explanations for these changes.…”