Causes of venereal sarcoma
The transmissible venereal sarcoma, which only occurs in the canis family (Canis Familiaris) and global distribution on all continents, has an unusual pathogenesis that has been seriously studied over the past 130 years.
To date, it has been clarified that this is a histiocytic soft tissue tumor that is transmitted from one animal to another during physical contact (sexually) by the monophilic phagocytic system (part of the immune system) of the organism that develops in the tumor by the histiocytic macrophage cells.
That is, the tumor cells themselves are infectious agents and, by penetrating into the tissues of a healthy dog by adhesion, provoke the development of the same tumor. In fact, infection occurs on the principle of allografts - when the cells of one allogeneic individual, getting into the body of an individual with a different genotype, take root, and the tumor loses its connection with the original host. It turns out that tumor cells behave like parasites.
At the same time, cells of tissues affected by venereal sarcoma have fewer chromosomes than normal dog epithelial cells (57-64 instead of 78).
Domestic veterinarians believe that venereal sarcoma in dogs can not give metastases, and the appearance of lesions in the mouth and muzzle is explained by the simple transfer of infected cells from the genitals when licking. However, foreign experts say that this tumor metastasizes in about 5% of cases, most often in regional lymph nodes, subcutaneous tissues, eyes, brain, liver, spleen, testicles and muscles.
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