Scratching/Sores Part 2

Question
I previously asked a question about my GP scratching so much that she caused herself open painful sores. I took her to the vet the next day b/c she was really miserable and I wanted her better fast. We originally thought it was a fungal infection, but the medication she was given didn't clear it up and a few days after I started treatment, she started loosing her hair in those areas. I started researching and thought she may have mange mites. I took her to a different vet and although her skin scraping came back negative he said she could still have it b/c they are hard to find. He gave her an oral dose of Ivermectin. She has to get her 2nd dose this week. Do you know if this medication is more effective given orally or by injection. She is not scratching nearly as much as she was, but I was expecting no scratching. He admitted he was no expert but he seems to know more than the 1st one. I just want my girl to get well fast. Also, once you get rid of mange mites, can they come back?  
Thanks for your help.

Answer
Hi Jennifer

Ivermectin is better given by injections because it then goes straight into the bloodstream and should therefore be more efficient at killing the mites.

Yes, mites can return but you just need to be vigilant in the cleanliness of the pig's living quarters. Give her a bath once every couple of months will also help.

Andy