Why Your Dog Panics in the Car, and the Two-Week Fix

Sickness or fear? They look the same
Drooling, panting, whining and refusing to jump in are common to both, which is why so many owners treat the wrong problem for months.
A useful test: sit in the parked car with the engine off, doors open, for ten minutes with something nice to chew. A car-sick dog is usually fine here. A fearful dog is not, and often will not get in at all. The stationary car separates the two better than any amount of observation on the road does.
If it is motion sickness
Young dogs are far more prone to it because the balance apparatus in the inner ear is still developing, and a good number simply grow out of it. Until then: travel on a light stomach rather than an empty one, keep the crate or seat facing forwards where they can see the horizon, crack a window for airflow and cooler air, and drive as though there is an open cup of tea on the dashboard.
If it persists, talk to your vet. There is genuinely effective anti-nausea medication for dogs, and it is worth asking about rather than enduring for a year.
If it is fear, the two-week plan
The goal is to break the chain of predictions the dog has built. At the moment, car means driving, and driving means arriving somewhere they dislike.
- Days 1 to 3. Meals fed near the parked car. Do not put them in it. Do not open a door with intent. You are only making the driveway boring again.
- Days 4 to 6. Doors open, dog invited in with something excellent, out again after a minute. Every session ends before they want it to.
- Days 7 to 9. In the car, doors closed, engine off, chew for two minutes. Then engine on, no movement, two minutes, off.
- Days 10 to 12. Reverse to the end of the drive and back. That is the entire trip. Repeat several times.
- Days 13 to 14. Two-minute drive to somewhere genuinely good, a field or a friend they like, then home.
The rule that makes it work: for the whole fortnight, no journeys to the vet, the groomer or the kennels. One bad trip in the middle undoes a week of good ones, so if an appointment is unavoidable, get a lift or start the plan afterwards.
What not to bother with
Reassuring a panicking dog in a soothing voice does not calm them, though it does no harm either. Forcing them in "so they get used to it" reliably makes it worse, because flooding an anxious animal with the thing they fear teaches them they were right to fear it. And a dog loose on a seat is both less safe and usually more anxious than one in a secured crate or harness, which gives them something solid to brace against.