Thank you!There are several reasons for a dog to have itchy skin (pulling the fur out is a sign of itchiness). The reasons a roughly broken into the following categories:1. Parasites - mites, fleas, etc2. Allergies - food, airborne (seasonal) or flea bite hypersensitivity3. Infections - yeast, bacteria, ringworm
, etcThe most common, by far, is a flea allergy, statistically speaking. This is true for any part of the world, without a doubt. Flea allergies are sometimes difficult to diagnose, because in some cases NO adult fleas are seen. A lot of this is because the dogs chew at their skin, removing most of the fleas... One of the distinguishing features of flea allergy is hair loss and itchiness along the back, toward the tail and around the tail base; this is the only skin condition that results in these symptoms. In many cases, the inflammation is so intense and there is so much skin damage from chewing, that infections come up (bacteria/yeast) and complicate issues, making the dog even more itchy. Fleas are easy to bring into the house; dogs can do this, people can do this (on our clothes), etc.In your situation, I believe it is most likely a flea allergy, even though you see no fleas (see above) and your other dog is fine (he/she may have fleas but not the allergy to them, hence no symptoms) and it sounds like neither is on flea prevention, making fleas even more likely. The only way to rule out fleas is to treat for them and see if symptoms subside, but in your case, inflammation and infection may need to be brought under control as well. It takes months to get rid of fleas, but if you apply a flea preventive to your dog, the signs of itchiness should begin to subside; often, that's how you know that flea allergy is the problem.Here is a helpful link to more info: http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=2604I hope this helps! Please let me know if you have any questions!!!