There are a number of reasons why dogs develop motion sickness. One of my clients' rescue Cavallier l was absolutely petrified of the car and just wouldn't go near it. Turns out he associated the car with being abandoned by his first owners. So how can we make this more pleasant experience for our dogs?
Adjust what your dog sees.
Watching the world speed by through a side window can nauseate anyone. Put your dog in the middle seat in the back so he’s more likely to look forward. Use a doggie seat belt or safety harness to keep him in place. You can also purchase special car seats which minimize movement around and provide some stability.
Keeping the car well ventilated, even a few inches of fresh air will equalize inside and outside air pressure and that can help reduce nausea.
Restrict your dog’s food intake.
Try withholding food for 12 hours before the car trip. Make sure they still get plenty of fresh water.
Favourite toys.
Bring something that smells familiar for your dog, whether it’s a favourite blanket or a toy or even a comfy bed. It will have a calming effect on your dog.
Natural remedies.
Holistic Hound is a small Irish company which does wonderful natural remedies for dogs. For motion sickness they have "Travel Well" herbal spray that may help combat the physical signs of motion sickness.
Desensitizing.
This one will involve training and if you're unsure where to start, contact a registered dog trainer. Starting slow by just sitting in the car with your dog for a few minutes at a time. Then slowly increase the amount of time you spend in the car and eventually go for very short drives down the street or even just the driveway. You'll need bags of patience and rewards such as toys or food or something else that your dog absolutely loves. If your dog is showing signs of stress or anxiety such as drooling, panting, shaking etc. take a step back and try again the next day.
Medication.
If you have tried everything then perhaps it's worth chatting to your vet about what medication you can give your pup to make the necessary journeys more tolerable for them.