The incidence of breast cancer is continuously increasing worldwide, as influenced by many factors that act synergistically. In the last decade there was an increasing interest in the possible viral etiology of human breast cancer. Since then, many viruses have been associated with this disease (murine mammary tumor virus, MMTV; Epstein-Barr virus, EBV; and human papillomavirus, HPV). Recently, BLV has been identified in human breast cancers giving rise to the hypothesis that it could be one of the causative agents of this condition. BLV is a retrovirus distributed worldwide that affects cattle, causing lymphosarcoma in a small proportion of infected animals. Because of its similarity with human retroviruses like HTLV and HIV, BLV was assumed to also be involved in tumor emergence. Based on this assumption, studies were focused on the possible role of BLV in human breast cancer development. We present a compilation of the current knowledge on the subject and some prospective analysis that is required to fully end this controversy.

DNA was extracted from lamb lymphocytes that were infected in vivo with a BLV strain after inoculation with the peripheral blood mononuclear cells from a persistently sero-indeterminate, low viral load, BLV-infected Holstein cow (No. 41) from Argentina. The DNA was PCR amplified with a series of overlapping primers encompassing the entire BLV proviral DNA. The amplified BLV ARG 41 DNA was cloned, sequenced, and compared phylogenetically to other BLV sequences including an in vivo high replicating strain (BLV ARG 38) from the same herd in Argentina. Characterization of BLV ARG 41's deduced proteins and its relationship to other members of the PTLV/BLV genus of retroviruses are discussed.

Most of the responses present in animals when exposed to stressors are mediated by the autonomic nervous system. The sympathetic nervous system, known as the one responsible for the “fight or flight” reaction, triggers cardiovascular changes such as tachycardia or vasomotor alterations to restore homeostasis. Increase in body temperature in stressed animals also activates peripheral compensatory mechanisms such as cutaneous vasodilation to increase heat exchange. Since changes in skin blood flow influence the amount of heat dissipation, infrared thermography is suggested as a tool that can detect said changes. The present review aims to analyze the application of infrared thermography as a method to assess stress-related autonomic activity, and their association with the cardiovascular and heart rate variability in domestic animals.