We had two beagle pups. Same thing...inground system. If these guys saw a squirrel two doors down, they’d rocket thru the “force field” and keep going like nothing happened.
I used to laugh at the Brittany ... he’d run on through & always give a “yelp” as he got shocked, but never slowed down. The Chesapeake Bay Retriever “Romeo” did the same thing ... steeled himself, gave a yelp as he went through & was off and gallivanting.
The CB ended up getting in trouble - got in a fight with a Doberman at a horse farm down the road on one of his gallivants ... one of the horses in the barn (expensive show horse) got upset & hurt himself banging around the stall. The dog’s owner was told he would be getting the vet bills & if the horse could not compete any more, he’d get a very large bill for the value of the horse. This was finally the event that convinced him to have the dog neutered, which resulted in a quieter, calmer, non-Romeo sort of dog.