Читать книгу Pet-Specific Care for the Veterinary Team - Группа авторов - Страница 245

There is no doubt that many cancers have genetic associations [2] but there is still much to learn about the genetics of cancer. Solid evidence exists that some cancers, such as those associated with dermatofibrosis, have a genetic basis, and a DNA test can even be used for that particular disorder. Pugs are predisposed to viral pigmented plaques, associated with papillomavirus. Lymphoproliferative diseases also appear to have well‐defined heritable risk factors in at least some breeds. In many other instances, definite breed predispositions exist, but in many cases a definitive genetic basis is lacking. In other cases, epigenetics and environmental causes may coincide with genetics to promote cancer. For example, the incidence of transitional cell carcinoma (TCC) has been steadily increasing in dogs over the years, and the risk of Scottish terriers developing TCC is approximately 18 times the risk of mixed‐breed dogs [3]. Further studies have suggested that this breed‐associated risk may be due to differences in pathways that activate or detoxify carcinogens, and exposure to lawns or gardens treated with phenoxy herbicides could potentially be associated with the increased risk of TCC in Scottish terriers.

Oncogenes are genes that when mutated, or expressed at high levels, cause normal cells to transition into cancer cells. The process is typically helped along by the effects of environmental carcinogens, viruses, and other stressors. In contradistinction to oncogenes, tumor suppressor genes, or antioncogenes as they are sometimes called, protect normal cells from transitioning into cancerous ones. A mutation in these genes can cause a loss of or reduction in this protective function.