[yorkietalkjilly]

Sounds like panic or pain. Tibbe has the occas. pain attack which can last up to 2 hours if I can't get him outside for vigorous exercise or some other distraction so I usually use boiled chicken or some other high value treat and get him to doing tricks or chasing his treats to distract him. But I've seen dogs in pain or ill shaking badly and isolating, too. I'd have him checked over by a vet to be sure it's not pain/illness but otherwise, it sounds like he hears some odd sound such as an electronic car opener or something like that that takes place to trigger his panic. Whatever causes panic, distraction to another activity is the best way to treat it since we can't talk over the fear causes with them and soothing can just exacerbate it.

Try not to empathize or pitty him during these times if it turns out to be panic & not pain or illness as this can reinforce the fear-based behavior and make him worse. It could be he's developed a tendency to panic and your new dog is somehow triggering his tendency to have some of the panic attacks but sometimes more than one thing can trigger them. Some people and dogs just tend to flood with adrenaline when scared/worried by something and it can trigger panic attacks & the shaking, won't subside until the adrenaline and the fear-cause is abated or distracted by something very exciting or intensely interesting or something really fun starts happening. Hope you can get to the bottom of it - I know it is worrisome to see them so uncomfortable!