Tumors: Hereditary vs Environmental
Tumors. Many rats get them. Some breeders claim to have bred them out. Others claim that's impossible. I disagree with both sides, although, I do believe tumors can be drastically reduced, even when caused by environmental/dietary factors. Tumors can be selected against and reduced with careful breeding and close documentation. (Mini rant: I've seen breeders state there is "no way" to keep track of their rats they adopt out. If you are a knowledgeable, responsible, ethical breeder, you will figure out a way! Although I understand it is impossible to keep in contact with ALL adopters, an ethical breeder works hard to develop and maintain a working relationship/communication with each and every adopter. That means they followup with adopters not just days after an adoption, but months or years later. The breeder should want to know how their rats' temperaments are and how their health has been. If a breeder follows up with the majority of adopters and keeps in contact, they will be able to monitor a line's tumor rate/percentage, respiratory sensitivity, hormonal aggression, etc very well. They should also be keeping multiple rats from each litter. I keep notes on all my breeders and how many of their offspring from past litters were reported to have any issues. I alter my breeding plans with this information I collect. If a breeder cannot do something similar where they can't keep track of their lines, then they should NOT be adopting rats out to the public, or in the very least, they should be honest that they DO NOT breed for health or temperament). I also read that a breeder stated a 50% tumor rate in rats produced by this breeder - any lines producing that amount of tumor-affected offspring should either be ended, or heavily selected against tumors by methods stated above (keeping multiple rats from each litter and following up with all adopters). Here is some research on how tumors are both hereditary AND environmental. If we remove the hereditary portion through CAREFUL and SELECTIVE breeding done by documentation through adopters/self, tumor rate can be drastically reduced, if not almost completely eliminated.
Article Name: Genetic mapping of mammary tumor traits to rat chromosome 10 using a novel panel of consomic rats.
Short Description: This research article by Adamovic et al (2008) discusses how one strain of rats are "highly susceptible" to cancer, while another strain is "completely resistant" with "resistant genes."
Article Link: https://www.ncbi.nlm.nih.gov/pubmed/18786441
Article Name: Identification of rat mammary tumor-1 gene (RMT-1), which is highly expressed in rat mammary tumors.
Short Description: This article by Chiou et al (2001) is about a gene which is "highly expressed in rat mammary tumors."
Article Link: https://www.ncbi.nlm.nih.gov/pubmed/11675151
Article Name: Hereditary Renal Cell Adenoma and Carcinoma, Rat
Short Description: Hereditary tumors, renal/kidneys, urinary tract.
Article Link: https://link.springer.com/chapter/10.1007/978-3-642-80335-2_13
Article Name: Hereditary renal cell carcinoma in the Eker rat: a unique animal model for the study of cancer susceptibility.
Short Description: "Tumor suppressor genes are recessive at the cellular level with respect to oncogenesis but often manifest as dominantly inherited familial cancer syndromes. This type of cancer syndrome arises in the Eker rat due to a genetic defect."
Article Link: https://www.ncbi.nlm.nih.gov/pubmed/8597118
Article Name: Hereditary Renal Cell Carcinoma in the Eker Rat: A Rodent Familial Cancer Syndrome
Short Description: Everitt et al (1992)'s article is about hereditary cancer and describes how a gene predisposes rats to cancer.
Article Link: https://www.sciencedirect.com/science/article/pii/S0022534717370878
Article Name: Genetic mapping of mammary tumor traits to rat chromosome 10 using a novel panel of consomic rats.
Short Description: This research article by Adamovic et al (2008) discusses how one strain of rats are "highly susceptible" to cancer, while another strain is "completely resistant" with "resistant genes."
Article Link: https://www.ncbi.nlm.nih.gov/pubmed/18786441
Article Name: Identification of rat mammary tumor-1 gene (RMT-1), which is highly expressed in rat mammary tumors.
Short Description: This article by Chiou et al (2001) is about a gene which is "highly expressed in rat mammary tumors."
Article Link: https://www.ncbi.nlm.nih.gov/pubmed/11675151
Article Name: Hereditary Renal Cell Adenoma and Carcinoma, Rat
Short Description: Hereditary tumors, renal/kidneys, urinary tract.
Article Link: https://link.springer.com/chapter/10.1007/978-3-642-80335-2_13
Article Name: Hereditary renal cell carcinoma in the Eker rat: a unique animal model for the study of cancer susceptibility.
Short Description: "Tumor suppressor genes are recessive at the cellular level with respect to oncogenesis but often manifest as dominantly inherited familial cancer syndromes. This type of cancer syndrome arises in the Eker rat due to a genetic defect."
Article Link: https://www.ncbi.nlm.nih.gov/pubmed/8597118
Article Name: Hereditary Renal Cell Carcinoma in the Eker Rat: A Rodent Familial Cancer Syndrome
Short Description: Everitt et al (1992)'s article is about hereditary cancer and describes how a gene predisposes rats to cancer.
Article Link: https://www.sciencedirect.com/science/article/pii/S0022534717370878