Have they said how the allergies affect her?
They can take different forms in dogs.
Two of mine have allergies. One of my yorkies has Hay Fever, he gets all snuffly & snotty in the spring & summer because of the pollen.
One of my Cairns has a food allergy but it's her skin it affects, she gets very greasy dandruff.
Neither of them have been at all difficult, or expensive, to control once I found what was causing the problems. With the Cairn, I just needed to change her diet to an anti-allergy kibble. I use James Wellbeloved Lamb & Rice & her skin has been fine once she changed to this.
The vet diagnosed my yorkie's Hay Fever. At first he gave him one week's course of cortisoids to take down the worst of the inflammation. Then he gave him Piriton to see if it would control it. Once we found it did, he said just to buy it from the chemist. It costs me £2.79 for 32 pills & he has two doses of 1/8 of a pill twice a day......so a fraction of a penny a day!
The worst part is dividing the tiny pills into eighths!