Consider the three legs dog. Maybe you own one or have seen them in the park or in any of the billions of Dodo videos about their. Lacking, but resilient, they evoke a kind of fawning sympathy from us humans, unmatched by the typical quadruped canine.
“People are attracted to specially adapted pets,” says Rene Agredano, co-founder of the Tripawds pet amputation site. “I think the attraction is that we just want to help them. We just want to make sure they are given an equal chance to have a happy life. “
Increasingly, this desire for help manifests itself as a prosthesis, especially in cases where the animal has lost more than one limb. Pets with artificial limbs have become a whole genre of their own videos. A cat with bionic hind legs. A turtle with wheels. The clips make the rounds on Facebook, where they add a little bit of optimism to the otherwise harsh flood, which is your news feed. 3D printing has propelled the industry forward. Printed prostheses can be lightweight, affordable and infinitely customizable. Doctors build beaks for birds. High school students build artificial dog legs in their spare time.
But not all pet prostheses are created equal. And some veterinarians and people in the tripod community worry that the proliferation of easy-to-make attachments could lead to unintended consequences for the creatures that carry them.
Dogs can lose a limb for several reasons. Maybe they were born with an abnormal limb or were hit by a car or developed a cancerous growth that required an amputation. A common trick among tripod lovers is that “dogs have three legs and a reserve.” It’s true, up to a point. Dogs adapt remarkably well to the loss of a limb, says Theresa Wendland, who specializes in animal sports medicine and rehabilitation at the Colorado Veterinary Specialists Group. But complications can occur as the animal makes up for what is missing. In older dogs and dogs with arthritis or other mobility problems, putting extra weight on the remaining limbs can be a big problem.
“It has an effective impact on the mobility of the spine,” says Wendland. “It must change the range of motion of the other members. It has to go in very unnatural ways. “
Prosthetics, if correct, can restore that range of motion. But as much as the heart melts, you see a three-legged dog running back on all fours, it’s not easy to build a proper leg. Wendland, who works with the orthopedic and prosthetic company OrthoPets to help dogs adapt to new limbs, says it’s an involved process that requires time and technical knowledge.
As with human prostheses, an animal prosthesis must be individually adapted to the wearer’s construction. This means taking into account the size, weight, height, position and gait of the animal. (A kit for a doberman will not fit on a dachshund.) To do this, orthopedists must study the animal’s movements and try to model a limb that will synchronize with the others. While the techniques vary, a standard process is to make a plaster cast, design the prosthesis based on photos and videos, and then build it with durable thermoplastics and metal. From there, adjust the finer details by hand until it works with the animal. The process can take weeks.
There is also the issue of the amount of member that needs to be replaced. The ideal point to place a prosthesis, says Wendland, is as low as possible on the limb. But if the entire limb has disappeared and there is no obvious point in attaching a prosthesis, it becomes much more complicated.
One foot up
3D printing has long been appreciated as a production revolution in many industries, including dentures. And now, a New Jersey design firm called Dive Design believes it is the solution for replacing full limbs. He collaborated with a company called Bionic Pets that builds exactly what its name implies: pet accessibility technology. Derrick Campana, who runs Bionic Pets, has long built handmade pet prostheses. (He even has a show about it called The wizard’s paws, which airs on Brigham Young University television.) About a year ago, he invited Dive Design bosses Alex Tholl and Adam Hecht to his lab in Virginia to see how he could improve the process.
“Something that kept popping up was the need to develop a complete limb prosthesis,” says Tholl. The members Campana built used too many resources and required too much manpower to be easy to manage. In addition, Tholl says: “With the waste involved, it just didn’t make financial sense. For us, then the wheels started to spin. “