Accepted Answer

It is very unlikely for a "fatty tumor" (or lipoma) to occur in this area. Also, lipomas are not usually itchy, so this seems unlikely.

What you are describing is more consistent with something called a "hot spot" (or moist dermatitis). These occur fairly commonly in dogs, and with proper medical attention, usually resolve in about 7-10 days. You should leave the area unwrapped (unless your dog is licking at it), and take your dog into the veterinarian as soon as possible for an examination. If it is a hotspot, the vet will shave the fur in the area to see just how far the area extends and then will cleanse it with a chlorhexidine or betadine solution. The usual treatment is a topical spray that contains Gentamicin and Betamethasone, and sometimes an oral antibiotic as well (depending on the severity of the infection).
I hope that this information is of help to you, and I wish you the best of luck with your dog. Please let me know if I can be of further assistance.

Dr. K

Expert:	Dr. K
Pos. Feedback:	99.6 %
Accepts:
Answered:	12/3/2008

Veterinarian

9 years experience as Veterinarian