I know that a local cable tech said they have had some issues due to solar activity. Nothing real bad but it is causing some minor problems, at least he is claiming such...
That's the usual meme to 1) they're too lazy to fix the problem or 2) they have no clue what is causing the problem.
Since there are several pets acting weird around your neighborhood then it might be a new factory that has gone in or an old one got a new machine that is making high pitched sounds. I understand he doesn't travel well but take him just 5 miles away and play at a park or visit a friend so he's no in the car. See if he's more relaxed. If so, then reduce the miles to 3. Then 2 miles. Then you'll know if it's in your neighborhood and can track it down. Has there been an upgrade in electrical wiring or new power poles? Maybe a tower of some sort. Or drive around with the windows open to see if there's a new smell.