No, because they breed a lot.
It's very rare.
pigs rats and moles
in some cases, but- its rare in the u.s
Maternal cannibalism in rats is rare. Too many rats in too small a space or not enough of a food source are usually the only causes for it.
True hairless rats (they have no whiskers) are rare. The type you are likely referring to are those that are bred from two rexes (curly haired rats). Hairless rats should not be any different from haired rats, other than the lack of hair of course! You'll find each rat has their own personality anyway :)
The hairless gene is a genetic mutation that occured naturally, and was bred purposefully. There are indigenous rats in some areas that have the hairless gene, but they are rare since natural selection does not favor a rat being hairless.
Rats not not always carry rabies, in fact most do not a an animal that has been infected does not have very long to live. Any mammal can carry rabies, but rats are among the more likely candidates as many rats can live in the same area, increasing potential for transmission form one animal to another.
There are no breeds in rats. All rats are the same type of rat. There are however, a number of variations which include different fur colour, fur type, ear type, tail type, and dwarfism. A rats with dwarfism are the smallest possible rat. They are quite rare though, so you will need to find a good breeder.
No, rats are vertebrates. Rats have backbones.
yes and no. if u like rats and they don't bite u then rats can be trained. if u hate rats then rats can't be trained.
no rats have gills, incuding water rats