Why would my dog's behavior in the car change suddenly?

My dog loves car rides. She runs out and jumps in the car, and even pouts when she can't go. All of a sudden, she has started shivering and panting while in the car. At times she also whines and jumps around a lot. I have has her for 2 years and this is new behavior. Any ideas why the sudden change in behavior? Should I take her to a vet? She only does this in the car.Thanks for your help. She's not cold. I turned on the heater full blast and wrapped her in a blanket. No luck.

Maybe she got cold or heard a noise that humans can't hear?

She sounds either overly stressed or overly excited.you need to do some desensitizing.

Amy,I've had dogs all of my life and I am an adult and there is one thing that I do know as far as dogs being in cars,they have to have a window cracked at all times so they can stick their noses out,I have read that it has something to do with their equilibrium and ears,I don't know if you have had the windows rolled up in the car,but if you have you may want to try this and see if this could be your dogs problem,I hope this helps you out.

Ask Ceasar Milan the dog whisperer

Maybe there is something in the car that she cant stand(that she doenst like).And maybe when she is getting in the car get her some toys.

Well, it could be hormonal changes if you got her as a puppy and she's just now turning two. It could be that she remembers some traumatic experience after riding in the car (i.e. a trip to the vet that she didn't particularly like, i.e having her spayed). It could be car sickness and her way to avoid vomiting. If she was adopted, she might be fearful that you're going to "drop/abandon her".I don't really see a need to take her to the Vet for this specifically, but you might mention it to the Vet during her next visit; they might suggest trying Dramamine a half-hour or so before a car ride (won't hurt, but get the proper dosage from the Vet) to eliminate the most probable, car sickness.Good Luck! - TugSamy mentioned something you might think about...dogs have a much greater sense of smell that we do...could there be some exhaust leakage into the car that she can smell and you can't?