my pet rat has no tail

Question
what could go wrong with my pet rat if she was born with no tail or at least a tail that never finished developing during the fetal development?

Answer
Some rats are genetically tailless, where they have several genes that, when combined, make the rat have a short tail or no tail at all.  Most tailless rats can be perfectly normal, but there are some problems that may occur.  Rats can also lose their tail shortly after birth if the mother bites it off, which sometimes happens during the delivery as she attempts to pull the baby out of the birth canal with her teeth.  Some less than reputable breeders will also amputate the tails of baby rats in order to sell them as tailless rats.

Some tailless rats have problems walking, as the shortened tail affects their spinal cord.  They may shuffle or hop instead of walking normally.

A rat uses its tail for balance, so a tailless rat may be a bit more off-balance than a tailed rat.  Most of them overcome this just fine and have little to no problems, but it is something to watch out for.

A female tailless rat may have a differently shaped pelvis than a tailed rat, and therefore should never be bred from as it could be hard for her to deliver the babies.

Rats also use their tail to help heat escape when they get too hot, so tailless rats can become overheated a bit more easily than tailed rats.  Keep an eye out for signs of heatstroke, which include laying stretched out with the bottoms of their feet up, labored breathing, and lethargy.  Rats should never be kept in a room that is more than 80 degrees Fahrenheit.

Hope this helps, good luck with your rat!