I don't think that such a thing exists.
It sounds like the dog might be suffering from an allergic reaction or even a yeast infection that has spread.
I suggest that you wash the area well with peroxide and then dry it completely. Then you can apply some neosporin ointment. If you don't start to see some results, you will need to see your vet.
Allergies are a problem for a lot of dogs. If this is the case, your vet might recommend that you use benadryl as an antihistamine to help with the itch.
Let me know if you still have more questions about this. I am afraid that I have not answered your question well.
