weight gain and hair loss

Question
I have a 3 yr old  blue and tan mini pinscher and she has been putting on alot of weigh in the last 8 months and now is loosing her hair. i took her to the vet and they did a thyroid test on her but it was negative.also she has been having these sores on her back by her tail. i started giving her weight loss food but i dont know what to do now with weight and also the hair loss please help?

Answer
If the hair loss started when you started the weight loss food, I have heard other such reports. You may have to let it go until she is down to a good weight and can go back to a regular food.  You may find this link helpful,  http://www.longliveyourdog.com/twoplus/RateYourDog.aspx

If the hair loss and sores started before the weight loss food, I would push the vet for more tests and perhaps try a different vet.