When you have four legs, losing one isn’t always a big deal.
The natural world is filled with examples of three-legged deer, lions, tigers, and other animals that thrive in the wild, even without human intervention.
In 2007, for instance, a three-legged moose was seen in Anchorage, Alaska, nursing a large and healthy calf. And that same year, camera trap photos revealed a healthy three-legged Sumatran tiger in Indonesia’s Tesso Nilo National Park.
But how do they do it?
It turns out that quadrupeds, the scientific term for four-legged animals, are far more resilient than humans when it comes to losing a limb. In some cases, the lack of a leg amounts to little more than a mild inconvenience.
Why? Because animals have a variety of coping mechanisms that allow them to thrive on three legs.
A balancing act
Veterinarians around the world perform countless leg amputations every day, but rarely recommend replacing the lost limb with a prosthetic. This is because most three-legged animals can balance beautifully without a fourth leg, artificial or otherwise. (Read: Injured Animals Get Second Chance With 3-D Printed Limbs)
When a quadruped loses a leg, it can often keep its balance by taking a “tripod” stance. By positioning the unpaired leg towards the center of its body, an amputee animal can distribute its weight evenly.
Balancing is especially easy for cats, squirrels, foxes, and other animals with long tails. These animals can use their long fluffy tails as counterbalances when climbing atop narrow structures.
Three-legged animals usually have no problem walking, jumping and running, says Monika Melichar, zoologist and founder of Woodlands Wildlife Sanctuary in Ontario, Canada.
Last spring, the sanctuary received a call about a five-week-old fox found with one of its front legs caught in a piece of lawn furniture. Attempts to free itself had resulted in permanent damage. Knowing the animal’s life was in peril, rescuers brought the fox, later named Timothea, to the sanctuary to undergo an amputation.
“Once she recovered from the trauma of the surgery, she was like a whole new fox. She was running, digging, climbing, doing everything a fox should do,” says Melichar.
The loss of a limb rarely prevents animals from engaging in natural behaviors, says Melichar. “Most [tripods] can reproduce, raise their young, and survive just as well as a four-legged animal.”
Unlike humans, who can take years to recover from the loss of a leg, animals bounce back with surprising speed.
Last summer, veterinarians at the Denver Zoo had to amputate a rear leg on one of their newborn African wild dogs. The brown-and-white speckled puppy, named Nigel, was walking around just hours after waking up from surgery. “It didn’t surprise me,” says Rebecca McCloskey, curator of carnivores and primates for the Denver Zoo.
“In general, animals are really quick to adapt to a change like that. Assuming the rest of their system is healthy, recovery happens quicker than you would think.”
In a study of the long-term effects of amputation in dogs conducted by scientists from the University of Georgia’s College of Veterinary Medicine, 91 percent of owners said their dog showed no emotional changes after their amputation. The study, published in theJournal of the American Veterinary Medical Association in 2015, also reported that 78 percent of owners said that their dog's recovery and adaptation exceeded their expectations.
(Watch: A Three-Legged Fawn Success Story)
Somebody to lean on
Although some quadrupeds can recover from an amputation on their own, many need a little help from their friends.
“In the wild, a solitary carnivore with a missing a limb may not fare as well as one in a pack,” says McCloskey. “Pack members really look out for each other.”
African wild dog pack members wouldn’t hesitate to offer food and protection to their amputated ally, she says. The strength of a pack is largely determined by its size, so offering aid to a weakened member is ultimately in the pack’s best interest.
To some extent, how well a three-legged animal is able to survive also depends on which limb they lose.
“It’s easier on the animal if the leg [they lose] is one of the hind legs,” says McCloskey. “There's a lot of power in those back legs, and the one remaining leg can handle that force and additional weight pretty easily.”
For foxes, tigers, bears, and other animals who use their front legs for specialized activities such as digging and capturing prey, the loss of a front limb can impede their ability to survive in the wild.
Because Timothea lost one of her front legs, Melichar and her team chose not to release the fox back into the wild.
“Foxes need both front paws to catch prey, so a fox that loses a front leg may not survive in the wild,” says Melichar.
Don’t hesitate to amputate
Even if Timothea can’t survive in the wild, she can live a long and happy life in captivity.
“There's no evidence to suggest that animals endure the same suffering that humans do after losing a limb,” says McCloskey. “As far as we can tell, they don't miss it at all.”
Despite this, pet owners often see euthanasia as being more humane than amputation. Owners often worry that turning their four-legged friend into a tripod would doom the animal to a life of limited mobility and depression. But McCloskey says that couldn’t be further from the truth.
“They can still live a completely normal and healthy life for a lot of years. It's definitely worth it to give them that shot.”