scabby skin on calicos back near her tail

Question
Thanks for helping Dr. Gotthelf -- my calico has developed a scabby-feeling, crusty, dry, area on her back. I have not been able to really part her hair well enough to see what it looks like. She seems to respond very appreciatively when I scratch her there (turns her head to the side, tongue moves in and out reflexively, yowls) but shows no other signs of being bothered by it. Do I need to take her to the vet, or can I just get some sort of salve or ointment for her and save the expense of the office visit?  

Answer
This is a condition called "miliary dermatitis."  It is how cats show skin allergies. Very often it is a flea allergy. You should take your cat to the vet.  Ask if your cat can have a shot of DEPOMEDROL, which is a long acting steroid that helps relieve the itching and crusting your cat is experiencing.  It can be repeated every 6-8 weeks. If there are fleas on the cat's skin, then use something like Advantage TopSpot to kill the fleas.