dog scratching

Question
i have a nine month old shi tzu puppy and recently have noticed her biting the bottom of her back at first i thought it was flees but wen i noticed she was biting tats in her fur.i started brushing her every day but she still bites by her tail and is now pulling out fur and a baldy patch is starting to form.when i checked easrly this week i noticed her skin is now red/pink and looks sore and when anybody touches it she turns her head suddently as if they have hurt her what should i do?


thanks in advance.

Answer
Hello Jenny,

It sounds as if she has a flea allergy. It only takes the bite of one flea to send an animal with a flea bite hypersensitivity (commonly called flea bite dermatitis)
into a frenzy of chewing. This usually shows up in the dorsal area just at the base of the tail, but can extend up the back (as far as the dog can reach) and down the legs. They will sometimes find an object to rub against for the areas they can't reach.
The way the allergy works is as follows:
The flea is a blood feeder, but in order for the flea to get the blood into their stomach, their saliva contains an enzyme that prevents the blood from clotting, so they can easily suck it in. When the flea bites, some of this saliva is "injected" into the bite area, which is then absorbed into the blood stream. For most dogs, this doesn't pose a problem, but for dogs with sensitivities, the enzyme creates a histamine reaction, just as pollen does to us and makes us sneeze. This reaction makes the itch terribly even long after the bite itself and as I said earlier in my answer, it only takes ONE FLEA BITE to start this cycle.
It would be a good idea since your dog has already created such a bad spot (with fur loss, redness, and pain) to take her to the vet. They will probably prescribe an antibiotic (such as cephalexin) and a steroid (like prednisone). The antibiotic will clear up any infection that may be trying to take hold (such as staph which is common with flea allergy) and the steroid with help with the terrible itching and pain. The steroids should probably only be prescribed for a short period, as long term use can be taxing on the liver and kidneys.
To prevent further problems, you may want to use some form of flea prevention that kills the fleas BEFORE they bite. I would also recommend that you start her on a good Omega 3 & 6 supplement, such as dermcaps or just use a good fish oil (salmon oil caps from the health food store), as they are great for controlling/lessening the inflammation response and they help aid in skin and coat health. You might also consult with your vet about adding Ester C to her diet regime, as this helps strengthen her immune system.
I hope you get this thing worked out and your baby get better soon!