Have you looked into doing drops for pets? Both of my dogs get bad seasonal allergies. Their paws get so itchy they will lick the fur off unless we get them help. The allergies start up in July and persist until the first frost of the season (late October or November).

We have done both shots and medications from our vet that help alleviate the symptoms, but they don't have any long term solutions. We've moved while having our pets, so we have had two different vets for this issue and they basically say the same thing and have similar treatments. They also say that it's a huge problem to the point where during a bad allergy season over half of their patient visits in a day are related to allergies.