The expert you requested is no longer active with the site. My name is ***** ***** I will be glad to be of help to you.
I'm sorry you are worried about Pachebel. From your description, it does sound like there may be a problem with his respiratory system, or it hurts him to breathe in, and that's why he's shaking and his muscles are tensing.
I'm glad to hear that he's eating, drinking, eliminating and acting normally, in all other respects; however, it would be advisable to have him evaluated by a vet in person, who will listen to his heart and lungs with a stethoscope and may run some tests (bloodwork, etc.) to find the basis of this shaking. Because he's a senior cat, any unusual behavior needs to be checked out as soon as possible, I'm sure you understand.
I hope all will be well with Pachebel and please let me know how he's doing and what the vet tells you. Thanks!
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