SQ said:
I haven't noticed any health differences.
But anytime you have inbreeding for recessive traits (like dumbo ears), you can get health problems.
I do know that if dumbo eared rats are bred to dumbo eared rats for a few generations, you get lots of health problems ... and unethical breeders and mills probably do this so all babies will be dumbo eared - instead of breeding dumbo eared rats to standard eared rats.
It really isn't as simple as inbreeding for recessives or breeding dumbos to dumbos. The issue has more to do with inattentive or irresponsible breeding. A responsible, reputable, ethical breeder will track the health and longevity of their rats. If an issue shows up, they will work to eliminate that issue, even if it means ending that particular bloodline. They use inbreeding and linebreeding as a goal to achieve this. Inbreeding/linebreeding can be used to show problems that are in the line. It can also be used to eliminate those issues. Constant outcrossing does nothing to eliminate problems, it really only introduces new ones. The difference is, with outcrossing the issues can hide for many more generations than it will with inbreeding and linebreeding.
Irresponsible breeders don't go through this trouble. They breed any random rat to any other random rat. Sometimes those rats are related. Sometimes they aren't. Actually, come to think of it, most irresponsible breeders do NOT inbreed or linebreed, because it's "bad". They actually make a point to outcross, a lot. This simply introduces more issues. And because irresponsible breeders do NOT track the health of their rats (not lines, because you can't have a line with constant outcrossing), there is absolutely no attempt to eliminate these problems.
Dumbo rats in and of themselves have no problems just because they are dumbos. The problems are more associated with the genetics or rearing of the rats. Poor upbringing can affect the animal in the long run, even if they receive great care in their new homes. Health is a much more complicated issue than simply "oh this variety isn't healthy, that one is" or "if I give my rats good food they won't have problems". It is much more complicated than color genetics, and has to do with numerous genes that may not be simply dominant or recessive. It's a very technical matter to eliminate health problems, and may take a number of generations to achieve, but it can be done, through careful, tracked breeding.
In my personal experience, dumbos are no more healthier or friendlier than any other rat. They are also no less healthy or friendly than any other rat. The differences I have seen have more to do with rearing and genetics. Rats with a poor upbringing have been more likely to have health or temperament issues. Rats bred randomly with no mind to health or temperament are more likely to have health or temperament issues. This does not mean other rats are going to be perfect, but it does mean they have a greater chance.
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