Ana I Faustino-Rocha - Faculty of Veterinary Medicine, Lusophone University of Humanities and Technologies, Lisbon, Portugal|Center for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), University of Trás-os-Montes and Alto
Mário Ginja - Center for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), University of Trás-os-Montes and Alto Douro (UTAD), Vila Real, Portugal|Department of Veterinary Sciences, UTAD, Vila Real, Portugal
Rita Ferreira - Organic Chemistry, Natural Products and Foodstuffs (QOPNA), Mass Spectrometry Center, Department of Chemistry, University of Aveiro, Aveiro, Portugal
Paula A Oliveira - Center for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), University of Trás-os-Montes and Alto Douro (UTAD), Vila Real, Portugal|Department of Veterinary Sciences, UTAD, Vila Real, Portugal

Objective(s): The present work intended to clearly define the most adequate humane endpoints in an experimental assay of mammary carcinogenesis in rats. Materials and Methods: Animals were observed twice a day; all parameters were registered once a week and the euthanasia endpoints were established in order to monitor the animal welfare/distress during an experimental assay of chemically-induced mammary carcinogenesis in female rats. Results: Fourteen animals developed at least one mammary tumor with a diameter > 35 mm. No animals exhibited alterations in the remaining parameters that implied their early sacrifice. Statistically significant changes were not observed in the quantitative parameters like the hematocrit and urine specific gravity among groups, not being valuable for the assessment of the health status of animals included in an assay of mammary carcinogenesis for 18 weeks. The remaining humane endpoints seemed to be helpful to monitor the animals’ health status.Conclusion: The alteration in only one humane endpoint (mammary tumor dimensions) does not imply the animals’ sacrifice; the endpoints should be evaluated in conjunction, in order to define the most adequate time in which the animals should be sacrificed.

Chemically-induced, Humane endpoints, Mammary cancer, N-methyl-N-nitrosourea, Rat, Welfare