If you saw an animal slowly suffocating to death—and there was no hope of saving it—what would you do? This is a question faced by the researchers, veterinarians, and trained volunteers who respond to whale strandings around the world.

"Most large whales, when they come to shore, they're already dead," says Craig Harms, an aquatic animal veterinarian at North Carolina State University in Morehead City.

But the ones that strand alive and can't get back out to sea face a slow, painful death unless someone intervenes. Some groups use explosive charges to kill the animal as quickly as possible. Others use exsanguination, which involves cutting a major artery where the tail meets the body, and the animal bleeds out. Some use drugs.

A new study published last week in the Journal of Wildlife Diseases identifies a mixture of sedatives, pain relievers, and a euthanasia drug that can make things easier for those dealing with a stranded whale—and is much gentler on the whale itself.

The primary goal is to relieve a whale's suffering, says Harms, one of the researchers involved in developing the new method. Without that intervention, a stranded whale is left to the mercy of sunlight, scavengers, and gravity.

Exposure to sunlight causes a whale's skin to blister and peel, almost like a third-degree burn. And their prone position makes them easy pickings for scavengers like seagulls. "The gulls really like to go for the eyes, and they don't worry about waiting until the animal is dead," Harms says.

In the end, without the buoyancy of seawater, a beached whale is crushed to death under the weight of its own organs and blubber. It can take from several days to a week for a stranded whale to die, the veterinarian explains. "It's a long, slow suffocation."

No Easy Solution

For groups that opt to use chemical euthanasia on beached whales, environmental concerns, human safety issues, and logistical problems can make carrying out that decision difficult.

One drug some groups use in their chemical mixes—a pain reliever and anesthetic called xylazine—can sometimes cause a whale to thrash around. That can be very dangerous for the people working around the animal, Harms says.

Another big stumbling block with current drug cocktails is the presence of a barbiturate called pentobarbital. Also used for euthanizing pets and livestock, pentobarbital first renders an animal unconscious so it doesn't feel pain, then stops the animal's heart.

But pentobarbital is a controlled substance in the U.S., and its use requires a license from the Drug Enforcement Agency.

The drug doesn't break down, so it persists in the environment. And pentobarbital can be absorbed through the mouth, which means it can affect scavengers feeding on a whale that's been injected with it—known as secondary toxicity.

A case study published in 2011 described a dog that fell into a coma after ingesting what investigators believed was the flesh of a humpback whale euthanized with a solution containing pentobarbital. The Australian shepherd eventually recovered after having its stomach pumped twice.

U.S. guidelines stipulate that if barbiturates are used on a whale, the carcass must be removed to eliminate the danger of secondary toxicity, says Teri Rowles, coordinator of the marine mammal health and stranding response program at the U.S. National Marine Fisheries.

Carcass removal is possible for smaller whales if they're accessible to trucks and cranes. But it's impossible to remove larger whales such as humpbacks, sperm whales, and male pilot whales.

For these large whales, pentobarbital is off-limits. Rowles notes that staff at the National Marine Fisheries have been trying since the early 1990s to come up with a workable solution that's safe for the environment, safe for humans, and humane for the whales.

She and Harms, together with several colleagues, came together several years ago to try their hand at a solution—which resulted in the drug cocktail and delivery protocol they describe in their new study.

A Better Way

Harms says he was spurred to try to come up with a better way after dealing with a stranded two-year-old right whale calf in 2009. It was in a hard-to-reach part of a beach in North Carolina, and by the time he and colleagues reached the animal, its skin was peeling and seagulls had been picking at its flesh.

Since they couldn't use pentobarbital to euthanize the whale, they decided to kill it as quickly as they could by exsanguination.

"That was one of the first live whales I had been close to," Harms says. "When you're standing there, and you can see the muscle ripple under the blubber, and it's looking back at you, and you don't have the tools to do right by it, that was hard." (Learn how scientists rescue stranded whales.)

So Harms, Rowles, and colleagues developed a new mix of four drugs—midazolam, acepromazine, xylazine, and potassium chloride—that, when administered sequentially, can euthanize a stranded whale more humanely without being toxic for other creatures in the environment or dangerous for people to work with. Midazolam is commonly used to relax people, and acepromazine to calm horses and dogs, Harms says.

Once the whale is quiet, xylazine is administered. If xylazine is given after midazolam and acepromazine, the whale doesn't thrash, Harms says, which makes it much safer for people to work around it.

"The xylazine offers pain relief and anesthesia to the point where we can give the final drug, potassium chloride," Harms says. Potassium chloride stops the heart.

The researchers also came up with a new way of administering those drugs using a garden sprayer connected to custom-made needles. The pressurized sprayer enables delivery of the right quantities of the necessary drugs. And the needles allow workers to access veins near the fins, which keeps them away from the dangerous tail end of the whale.

They distributed their new protocol and equipment to stranding groups around the country, including the Marine Mammal Center in Sausalito in northern California. Shawn Johnson, director of veterinary science for the center, who was not involved in the study, praises the new approach.

"People have been talking for a while now on finding other ways of euthanizing whales," he says, and this new method appears to be very safe and humane.

"Here in California, it's rare that we have large whales strand, unlike on the East Coast," Johnson says. Although he and his colleagues have not used the new method yet, they've acquired all the recommended equipment and drugs.

"Euthanizing whales is not an easy way out," Harms says. "It's not something we enjoy doing." But now, people confronting the problem of whale strandings have one more tool in their kit to help them do what's least traumatic for the distressed creatures.