Allergies are caused in three ways, inhaling, ingesting or by contact. But what brings them out is a low immunsystem! And Vitamin C and minerals and also Brewers Yeast Vit B for skin, missing in diet, plus antioxidants, feed more fresh meat/bones, green leafy vegetables, yolks, and lots of fruit.
Start by giving them Silver colloid, an ancient natural anti-biotic available in health stores. It also strengthens immune system.

But do remember to check their yard for contact dermatitis. Are there any poisonous plants? Do they lye on concrete with petrol? Does your wife use a lot of disinfectants? Air sprays, Washing detergents, toilet cleaners, all are toxic to dogs! Their nose is so much finer tuned then ours.
And 99% of all dermatitis is caused by fleas! So if you have fleas you need Frontline, it kills life fleas. You also need to spray your car, your carpets, their lying place outside, anywhere your dogs are, with simple fly spray, again in one week, and again one week later. So three times, one week interval. Other places you can hose down. Inside tiles or lino would be good to have one of those floor steamers, the heat kills eggs in grout etc. I use one called the shark, fantastic machine. Carpet you need fly spray again. Wash everything else like bedding, yours too, LOL.
You can also wash your dog with Malaseb by Dermacare. Make sure you leave it on for 10 Minutes! On the biggest sores put some liquid antiseptic solution like Betadine, but don't let them lick it off while wet!

After all that you should all feel so much better, LOL.