I am about to rehome a shih tzu which is a year old and has dermodex mange-the smell is very bad and I was just wondering if and when the smell will go-this is my first dog and I hope an expert can help

Don't think the mange will smell it will be secondary infections that are causing that. The vet may be able to help by the control of the secondary infection whilst the dog is undergoing treatment for the demodectic mange. The fact that the dog has had to be re-homed will not have helped as the demodectic mange flare up is likely to happen alongside stress and one would think that this poor dog is stressed.

I always thought it was Sarcoptic (fox/red) mange that had a characteristic smell, mousy I have heard it described as.

This is the type that is caught rather than the type that most dogs have and only causes issues when the immune system is not functioning properly/is under extreme stress.

Can only go by what the OP says, but agree I have never known it smell but there are often overlying infections.