Yes, 5 mg. is a small dose but it's all that's needed for us. Your vet can tell you what dosage is appropriate and you may have to play w/the dosage for a while.

As for starting and stopping, that hasn't worked for me. It's important not to miss a dose or the stressing and/or inappropriate behavior can start up again. If you only want to medicate your cats while you're away, perhaps talk to your vet about amitryptilene. A small dose of that also keeps them calm. I was dosing my cats for a different reason, inappropriate peeing, so that drug only worked for a little while.

Also, have you tried Feliway? There is a plug-in that you can try and Catty1 has had great success w/spraying just a little tiny bit on her cats' stretchy collars to keep them from stressing. She swears by it. Once again, I had no success w/it. I tried the plug-ins and my cats peed on it. LOL However, your situation is due mainly to separation anxiety so it may work for you. Perhaps PM Catty1 and see what she says. I'm sure she'll be happy to help.