Zoe here is a short list of things that can give your puppies and big dogs itchy spots.
Try to wash all bedding and dog towels in a non bio powder, with no fabric conditioner at all.
Bath your pups in baby shampoo
Air fresheners, the ones you spray around
Carpet fresheners.
Some of the perfumed disinfectant.
Floor cleaners
The perfumes in some products can cause problems it can be a case of changing products and the process of elimination.
Didn't see Ali's post
