Hi from New Zealand. I have briefly read your problem and thought i might be able to help. Years ago My x-husbands pig dogs had mange problems and only got rid of them by using INJECTABLE IVAMACTIN. Currently i have a boxer pup with very itchy skin and the vet told me to try human antihistamines, which i have used in conjunction with brewers yeast and garlic. She is 90% better. I only used the antihitamines for 3 days on the adult dose, and daily sprinkle the yeast and garlic in her feed. Hope that helps, Megan.