Is it normal for a big dog to shake?

depends on the breed of dog and its location... some dogs big or small suffer from anxiety issues do to traumatic events that have happened to them when they were younger or first born.... its location depending on the weather some dogs don't do well in the cold. try petting him or her while saying your ok and put your chest next to its and let it feel your breathing. meaning try to control its breathing and make it feel safe. if that doesn't work i would take it after about a month of solid doing this a couple times a day for at least 30 mins at a time then i would take it to your vet. it could also be separation anxiety or pack leader issues... they need to know who the alfa is. when they get like that you need to let them know to stop and that everything is ok. i hope this helps:) yours truly, dillan