Chiggers are driving my dog crazy with the itching.?

We have a bad Chigger prolem here in Ar. I have Dachshunds and they are low to the ground and can't keep out of them. We spray where we can, but they go other places we can't spray. Is there anything that can be used for the itching?? They have worn all the hair off their undersides from scratching on the gravel in the driveway. We have skid marks all over from them dragging their bodies over the gravel. I feel so bad for them. It has to be just miserable for them. I know how I feel if I get even one Chigger bite. They have hundreds. So if you know of something PLEASE tell me. Thank you so much, Judy