Alternate Location: partially published in SEFMA Newsletter Vol. 1 Iss. 1
Culling For Tumors
Written by A. Hamilton in October 2007
Most fanciers today track lines for tumors. Even after a mouse has left their mousery, fanciers continue to stay in touch with the adopter to track the line and whether or not an animal has developed a tumor. If a tumor develops, many fanciers will contact anyone and everyone who has mice from that line.
Once a tumor has been discovered in a line, the biggest question that remains is how far does the fancier go to prevent future tumors? Some fanciers will opt to cull an entire line just because of one mouse that has developed a tumor. This is like “shooting oneself in the foot.”
Any fancier can just take the information provided and choose to immediately cull the line. However, it is in one’s best interest to gather more information on the subject before deciding to completely do away with the line.
First, one must determine whether or not the tumor in question is, indeed, hereditary. The majority of cancerous tumors are the result of environment. Mice are a species much more prone to tumors and cancer, which is why they are invaluable to cancer research. So exposure to something that could take years or millennia to cause cancer to a human could result in a tumor within a matter of months for a mouse.
Secondly, it is a sad fact that several fanciers do not know the difference between a tumor, an abscess, or a fat pocket. So if one has a mouse that has a parent or sibling be diagnosed with a tumor, the first two questions one should ask the breeder are: “Is this definitely a tumor? Is this definitely hereditary?” If the breeder is not certain on the answer to either question, then one should weigh their decision very carefully before deciding to cull the line. You should also ask questions about the health of the rest of the line. For example: “How many other mice in this line have had tumors?” “Were the mice in your care when the tumor was discovered?” “What was the common relation in the line for tumors?”
Lastly, a lot of tumors are discovered while the mouse is in the care of an adopter, not the breeder. Once a mouse has left the care of a breeder, it is almost impossible for that breeder to say with 100% certainty that what the adopter is reporting is indeed a tumor and how a tumor developed. If 3 different adopters with mice from a similar line all contacted me reporting tumors on their mice, I would still be inclined to believe that the line was clean for 2 simple reasons:
- I am not 100% positive that what is being reported is a tumor, and not another problem. Unless I am given a report by a vet, I can not believe it without a doubt.
- I have no control over the mouse’s environment at this point. So there is no telling what could have caused the tumor. It could have been exposure to a certain cleaning solution, an aerosol air freshener used in the home, a certain type of food, etc. There are a lot of products that we use daily that cause cancer over prolonged periods of time. Unfortunately for mice, that exposure takes a lot less to develop a tumor.
If a breeder contacts you about a tumor cropping up in a line, ask questions and ask the breeder how positive they are it is a hereditary tumor. Also ask for proof for their theory. Make the breeder back it up before you cull a whole line. With careful selection, even tumors can be bred out of a line.