my rat has bald arms

Question
Hi,
Just a quick question, over the last 3 weeks the tops of my hooded rat's arms have become bald up to her elbows. They are fed well, given plenty of exercise and toys but she is nibbling them. The other rat with her has no bald patches at all.
What do you think the problem could be?
Kind regards,
Alex

Answer
 The most likely culprit is an external parasite such as mites or lice.  Buy a single tube of puppy / kitten Advantage or Revolution from your veterinarian and, using a 1cc syringe or eyedropper, apply a single drop to the back of your rat's neck.  Clean out the cage really well, including all toys and accessories, and repeat the dose in two weeks.  This will get rid of any external parasites on your rat.  To prevent reinfection, avoid contact with other rats and freeze bedding to be used for 24-72 hours before putting it in your rat's cage.

 Even though your other rat has no symptoms you should treat them both anyway, as it is highly contagious (to rats only) and if the parasites have no place to go they will readily jump on the other rat.

 If this treatment doesn't help it could be an allergy or even a psychological problem called barbering.  Sometimes rats who are bored or stressed can chew the fur off their own bodies (or off other rats' bodies).  If her skin appears to be fine and only the hair is affected this may be the case.  All you can do is try to remove any sources of stress and make sure the rats are taken out as much as possible so they don't get bored.  I hope this helps answer your question, good luck with your rats!