Flying is moderately to highly stressful for most dogs, though the intensity depends on the dog’s breed, temperament, and how they’re transported. Physiological studies show that air travel raises stress hormone levels above baseline, with the most intense spikes happening not during the flight itself but during loading and unloading. The good news: serious incidents are rare, with U.S. airlines reporting just 13 total animal incidents (deaths, injuries, or losses) out of 161,335 animals transported in 2024, a rate of 0.81 per 10,000.
What Happens to a Dog’s Body During a Flight
Researchers have directly measured stress hormones and heart rates in dogs before, during, and after air transport. Plasma cortisol, the body’s primary stress hormone, rises significantly above resting levels during the overall travel process. In one study published in the Canadian Journal of Veterinary Research, average cortisol levels after transport were roughly 40% higher than baseline. Salivary cortisol, another reliable stress marker, was elevated both before and after air transport, suggesting dogs begin experiencing stress during the pre-flight process, not just in the air.
Heart rate data tells a more specific story about which parts of the journey are hardest. Average heart rates during flight stayed in a relatively calm range of 80 to 90 beats per minute, close to the normal resting rate of about 75 bpm for adult dogs. But during loading and unloading, heart rates spiked significantly, with peak values exceeding 180 bpm in some dogs. For context, dogs exposed to acute stressors in laboratory settings show peaks of 146 to 181 bpm. Loading onto the aircraft was more stressful than takeoff, flight, or landing by a clear margin.
This pattern matters because it means the flight itself is not the worst part. The handling, unfamiliar environments, separation from owners, and crate confinement surrounding the flight generate the biggest stress responses.
Why Flat-Faced Breeds Face Greater Risk
Brachycephalic breeds (bulldogs, pugs, Boston terriers, French bulldogs, and similar flat-faced dogs) are in a different category of risk. These dogs often live with a chronic airway obstruction that narrows their breathing passages at multiple points: compressed nostrils, an overly long soft palate, an oversized tongue relative to their mouth, and sometimes an abnormally narrow windpipe. Many flat-faced dogs that seem fine at home are actually experiencing chronic low oxygen levels, similar to what happens in humans with obstructive sleep apnea.
Add the stress of air travel to already compromised airways, and the combination can become dangerous. Stress causes panting and increased respiratory effort, which is exactly what these dogs are least equipped to handle. Their higher baseline blood pressure, increased risk of aspiration pneumonia, and tendency toward blood clotting disorders all compound the problem. English bulldogs and other screw-tailed breeds are particularly prone to narrow windpipes, which becomes a serious liability when breathing demands increase. Many airlines have banned or restricted these breeds from cargo travel for exactly this reason.
Cabin vs. Cargo: Which Is Less Stressful
The instinct most owners have is that cabin travel is always better, and for small dogs on short domestic flights, that’s generally true. Being near you, in a familiar carrier, with the ambient noise and activity of the cabin rather than the isolation of a cargo hold, can make a significant difference for a dog that’s already accustomed to travel.
Cargo holds, though, aren’t the dark, freezing spaces many people imagine. They’re pressurized, temperature-controlled, and ventilated. For larger dogs who can’t fit under a seat, cargo is the only option, and it has its own advantages. There’s less handling and fewer transitions between environments compared to hauling a crate through security, gate areas, and boarding. For long international flights especially, fewer disruptions can mean less cumulative stress. The key variable isn’t really cabin vs. cargo. It’s how many transitions the dog has to endure and how well they tolerate crate confinement.
How Crate Setup Affects Comfort
International Air Transport Association (IATA) regulations require that a travel crate be large enough for your dog to stand fully upright, sit without their head touching the top, lie down in a natural position, and turn around while standing. The crate dimensions are calculated from your dog’s specific measurements: length from nose to tail base, height from floor to ear tips, and shoulder width. Flat-faced breeds require a crate at least 10% larger than these standard calculations.
Ventilation requirements are equally specific. At least 16% of the total surface area across all four sides must be open ventilation, distributed across the upper two-thirds of each wall. One full end of the crate (often the door) must be welded wire mesh. These specifications exist because airflow inside a sealed crate drops quickly, and poor ventilation amplifies both heat stress and anxiety. If you’re buying a crate for air travel, measure your dog carefully and size up rather than down. A cramped crate turns a manageable stressor into a serious one.
Sedation: Why Vets Are Cautious
Most veterinary organizations advise against heavy sedation for air travel. The reasoning is practical: a heavily sedated dog can’t adjust their posture, regulate their body temperature as effectively, or respond if something goes wrong. If respiratory complications develop mid-flight, there’s no one in the cargo hold to intervene, and sedation makes those complications both more likely and harder to manage.
That said, leaving a severely anxious dog completely unmedicated isn’t ideal either. The current veterinary consensus leans toward mild anti-anxiety medication rather than true sedation. The goal is to take the edge off without impairing breathing or coordination. Finding that balance is tricky, which is why this is a conversation to have with your vet well before travel day. They can assess your dog’s specific anxiety level, airway health, and any conditions that would make medication riskier.
What Makes the Biggest Difference
Since the research clearly shows that handling and transitions cause more stress than the flight itself, the most effective preparation focuses on those moments. Crate training weeks or months before travel is the single most impactful thing you can do. A dog that already views their crate as a safe, familiar space will have a dramatically different experience than one being confined for the first time at an airport.
Timing also matters. Direct flights eliminate layovers, which means one loading and one unloading instead of multiple rounds of the most stressful part of the journey. Early morning or late evening flights during summer reduce heat exposure on the tarmac, where dogs in crates can be vulnerable before and after the climate-controlled portion of travel. Exercising your dog thoroughly before heading to the airport can lower baseline arousal, making it easier for them to settle during the wait.
Freezing water in the crate’s attached dish gives your dog something to lick during the flight without the risk of a full water bowl spilling immediately. Placing a worn piece of your clothing inside the crate provides a familiar scent. These are small interventions, but for a dog whose stress peaks during separation and unfamiliar handling, familiar sensory cues can genuinely help.
Dogs Most and Least Suited to Flying
Young, healthy, medium-sized dogs with normal muzzle length and a calm temperament handle flights best. Dogs that are already comfortable in crates and have been exposed to car travel, crowds, and novel environments tend to show less dramatic stress responses.
Dogs at highest risk include brachycephalic breeds of any size, very young puppies, elderly dogs, dogs with heart or respiratory conditions, and dogs with severe separation anxiety. Extremely large breeds face practical challenges too: oversized crates are harder for ground crews to handle smoothly, and longer loading times mean more time in the highest-stress phase of travel. If your dog falls into a higher-risk category, ground transportation or professional pet transport services that use climate-controlled vehicles may be a less stressful alternative for domestic travel.