He was bred for good temperament, and in fact, many dogs from his breeder work as therapy dogs. When he was a wee pup, the vet treated him with NexGard. Pets treated with these products seem OK for a while. I wonder about the dogs who are not so reactive to these insecticides, who may suffer chronic, unnoticed side-effects. This likely comes from dogs and their beds being washed in homes, and from treated dogs being allowed to play in outdoor waterways.