A hot spot can develop from any type of irritation or abrasion...from a scratch, a flea bite, etc. It usually becomes inflamed from the dog licking or chewing it repeatedly, and can become infected. Something in that area is bothering or itching her. If she doesn't have a flea or allergy problem, she might have impacted anal glands, in which case you should take her to your vet and get it checked out. In the mean time, keep it clean and dry, and try to keep her from getting to it. Put a pair of pants on her, or fashion an elizabethan collar(or get one from your vet). I used to have a Dobie with lick granulomas and had to wrap his feet on a regular basis to get them to heal up. Good luck and let us know how it goes.

You'd have to see what's under the fur.

A hotspot is red, wet/moist, and literally hot. It is an area of intense inflammation, with secondary bacterial infection. A hotspot usually has thick smelly pus.

The best treatment for a true hotspot is to 1) take care of the underlying cause if possible 2) allow the wound to air out (therefore no ointments or topicals to impair air flow) 3) antibiotics +/- steroids to control the infection and inflammation. Some people can use steroid sprays to control the itching, but Aleks hated them and I was stuck with systemics.

Aleks had 4 in his lifetime, also when he was older but I think it had more to do with us moving to NC than his age. Many more bugs, molds, pollens, and allergens for him here than in MD. 2 of his hotspots I just clipped and prevented him from scratching/chewing and he did fine. The other 2 were very infected and he needed antibiotics for one, and steroids and antibiotics for the other. I think he had been bitten by a flea or other insect, depsite his TopSpot Plus. This year has been really bad for fleas in most areas, so it wouldn't surprise me if your dog got bit despite your treatments.

If it doesn't feel hot to the touch or isn't moist, I'd take Ellie in to the vet and make sure everything is OK. Some dogs with anal gland problems will chew/lick next to their tails for some reason instead of concentrating on the actual problem area.

Hot spots can be hard to treat, you might have to go to the vet to get another type of anti biotic. My pup has had two bouts, both attacked his face after being at the vet. I suspect an unclean table. They spread quickly and the longer they go untreated the harder they are to combat, The vet will shave the area, if have not already and give your dog a heavy dose of anti biotics. good luck

I second the check for impacted anal gland advice. But if that isn't it and the vet cannot find any other cause (like a true hot spot), try giving her a bath with oatmeal soap. They make it for dogs (I get mine at PetSmart, but it's probably widely available).

That takes the itchies from my 15 year old shep-mix. I think as they get older, sometimes they just get really dry skin.

the base of spine just above the tail is prime flea allergy site. Even if you don't see any fleas this is the area that a flea allergy reaction is most likely to occur. It just takes one bite.
If the dog is licking, chewing at it's anus, than your looking at anal sac problems and or fistula, worms, etc.
Hot spots don't occur on the anal tissue, but they will show up just about anywhere else by anything that makes the dog chew at the skin, including insect bites, dry skin, as well as any bone or joint problems.There are a lot of good home remidies to use BUT being no one can diagnos without seeing the site exactly it's best to have your vet take a look.