Do Dogs Get Used to the Car? What Four Studies Found

Eighteen beagles took part in one of the plainest experiments in canine science. Over six weeks at the University of Veterinary Medicine in Vienna, they were put in crates in a van and driven for an hour, sometimes two, on a route that was a quarter city traffic and three quarters four lane motorway. Before and after each drive a researcher took a swab of saliva. The stress hormone cortisol in it rose on every trip, to about eight times its starting level on the two hour drive, and the third week's trip produced no smaller a rise than the first.

That study, published in Animals in 2020 by Herbel and colleagues, is the one most often quoted when owners ask whether a car journey stresses a dog. Three more have since looked at the same question, and they do not quite agree on the part owners most want answered: does a dog get used to it?

What Vienna Measured

The beagles were between one and four years old, about 14 kilograms (31 pounds), and had never been transported. Six made three one hour trips in consecutive weeks and then a two hour trip in week six; six first spent time crated in a parked van; six stayed in their kennel as controls before their one journey. Parked, cortisol barely moved. Moving, it climbed every time: in the blood it roughly doubled after two hours, in saliva it rose about eightfold.

Heart rate told a slightly kinder story. It jumped as each journey began and settled in the second half, so the start of a drive is the hardest stretch. The cameras found the dogs mostly sat, and what they did most was lick their lips, something they did not do in the parked van. Yawning grew more frequent the more trips they made. The team read some of this as motion sickness and said so plainly: "There was no habituation with repeated transports, and transported dogs may suffer from motion sickness." The work was paid for from the university's own budget.

A Ten Minute Drive Against an Empty Room

In 2023 a team at the Waltham Petcare Science Institute set two familiar stresses side by side. Forty dogs, Labradors, beagles and Norfolk terriers, were either left alone for 45 minutes in a room with bedding, toys and water, or driven for ten minutes in a crate in the back of a minivan, never above 10 mph but with a sharp U-turn on the route. The drive came out worse. The authors concluded that "traveling in a vehicle was likely more stressful than being separated from conspecifics and humans," conspecifics being other dogs.

The study was really a test of cannabidiol, the hemp extract sold as CBD. Dogs given a single dose two hours before the drive had lower cortisol afterwards than dogs given a dummy capsule, though their heart rates were no different. The paper, published in Frontiers in Veterinary Science, was funded by Mars Petcare, which employed all four authors and makes dog food and provides veterinary care. The authors listed its limits themselves: three breeds, all research dogs, none chosen for being anxious travellers.

Six Months of Short Drives

The same group then ran the long version. Nineteen dogs took the same ten minute drive four times, at the start and at eight, sixteen and twenty four weeks, with a daily dose of CBD or a dummy throughout. That 2024 paper in the Journal of Animal Science is the first of the four to find any easing. In the dogs on the dummy, cortisol and whining "did incrementally decrease over time," which the authors read as the dogs' stress responses to the car having "diminished with multiple exposures." The CBD dogs had a smaller rise in cortisol over the first three drives, and that difference "was gone by week 24."

The easing was modest. Cortisol, heart rate, lip licking and yawning still rose from the dogs' resting level on the last drive, six months in, and the authors described car travel as a stressor with "limited habituation following multiple exposures without intervention." They were also candid that a short, low speed loop, with dogs who lived at the research centre and rarely rode in vehicles, is not much like a family car on a motorway.

The fourth study, published in 2025, gave 54 dogs four drives about four weeks apart and tried CBD treats at two strengths and a third treat that added L-tryptophan and alpha-casozepine. Here the first drive produced the largest rise in cortisol, and after that the team saw "no further habituation." Only the third treat made a measurable difference, to the rise in cortisol and nothing else, and the authors called the effect mild. The single dose result from 2023 did not repeat. Mars Petcare paid for this one too, and its staff wrote it.

Reading the Four Together

Side by side, the studies agree on more than they disagree. A car journey raises a dog's cortisol every time, whether it lasts ten minutes or two hours, and a moving car does it where a parked one does not. The first journey tends to be the worst, and the start of any journey is harder than the middle. Lip licking and yawning are the signs that turn up most when the dogs are filmed.

Where they part is on getting used to it. Vienna saw no easing over three weekly trips. Waltham saw some across six months in 2024, and none after the first drive in 2025. A few weeks of practice is unlikely to turn a nervous traveller into a calm one, and whatever easing comes is gradual and partial. The Vienna team allowed that habituation "over a longer time-period cannot be excluded," and the six month study is the best evidence so far that some does come.

None of the four tested what most owners actually do, which is take a family dog used to the car on an ordinary journey. Vienna's beagles had never travelled, the Waltham dogs in the 2023 and 2024 studies lived at the research centre, and three of the four drives were ten minute loops at no more than 10 mph. Three of the four studies come from one company's research centre and were built to test a supplement. Nothing in them makes a case for giving a dog CBD before a trip: the effects were small, did not repeat from one study to the next, and had gone by the end of the longest one.

Before the Long Drive

For an owner planning a day in the car, the studies point at the first trips and the first part of every trip. If easing comes, the six month study measures it in months rather than a weekend, so the practice runs belong well before the holiday, not in the week of it. The lip licking and yawning the researchers counted are worth watching for, because in Vienna the team read them as possible motion sickness, which has its own remedies in Can Dogs Get Carsick?.

How to get a dog ready, from crate training to how often to stop, is in Training Your Dog to Travel and Driving With Your Dog. The science adds something simpler. A car is hard work for a dog even when it looks settled, and in Vienna the beagles sitting quietly in their crates were carrying around eight times the cortisol they started the drive with.