The tan fuzzball came to the veterinary clinic with a softball-size lump near the armpit of his small body.

Lumps and bumps are common in aging dogs, and some are trouble, like cancer, while others are annoying, such as a cyst near the eye. For this dog, Zlo, the benign fatty tumor on his chest was making it hard to walk.

Each time, Dr. Salifou Bishop, a Towson veterinarian, has to decide if surgery is the answer. Some dogs are too frail, and some bumps are too awkwardly placed, for a scalpel. And then there’s the cost.

“It’s not always possible,” said the veterinarian at Loving Pet Care Hospital.

So when a pair of biomedical engineers approached him several years ago and told him about a device that could freeze instead of cut the bumps, Bishop was interested but wanted to see the data from their studies. Not long after he became one of the first veterinarians to use the cryotherapy tool.

Created as a student project at Johns Hopkins University, the device’s aim was to make the procedure and recovery simpler and more affordable for dogs, cats and other pets. The technology works by putting carbon dioxide under pressure to drop the temperature to minus 79 degrees Celsius — the same concept as when you purse your lips and blow air to cool your food, only a lot more intense, said Bailey Surtees, one of the inventors.

The device resembles a hot glue gun with an elongated probe that can be switched out to accommodate different sized animals and issues. It’s inserted into a bump for a few minutes, and the frozen cells die and are absorbed back into the body over weeks. The incision is closed with a few stitches.

Bishop said he’s had one complication from the first several procedures from a dog’s excessive licking. The site can be a bit itchy, he said.

For the procedure, Zlo needed only to be sedated with a shot, rather than put under the heavy anesthesia and breathing assistance that is normal for surgery, which can be harder for an 11-year-old dog. The lump was shaved, revealing a bruise, likely from rubbing on the ground.

“It could have ruptured,” leading to complications such as infection, Bishop said.

With direction from Katie Ogg, a clinical engineer from the device maker, now called Kubanda Cyrotherapy, Bishop carefully inserted a metal probe into the lump that quickly began to feel rock hard. He took a break for several minutes and then dropped the temperature again, a cycle of freezing and thawing that more effectively kills the tumor cells over the next few weeks.

After about a half hour, Zlo was snuggled under some blankets, sleeping it off.

The cryotherapy tool’s creators, Surtees and her partner Clarisse Hu, graduated in 2017 and began marketing it in 2020. They plan to continue working with Hopkins on more trials to show it works well on more types of cancers, more varieties of animals, such as horses, and eventually, on people.

“Carbon dioxide is cheap and super accessible around the world. Anywhere there is soda like Coke, you can use this tool because the canisters are ubiquitous,” said Surtees, CEO of Kubanda, which means ice in Zulu.

There are no similar tools for animals, though there are for people. For the most part, they use argon or liquid nitrogen, more expensive elements not readily available outside of hospitals in wealthy countries.

Surtees said if human trials show their carbon dioxide-based device is safe and effective, and passes federal regulatory muster, the tool could be more accessible around the U.S., such as in dermatology offices.

Perhaps more importantly, the technology could also be used in countries that don’t have resources or infrastructure for the existing tools, widely expanding access to potentially life-saving cancer treatment.

The then-students had humans in mind when they first began working on the device, but found a lower regulatory bar for animals. And, Surtees noted, “We are animal lovers.”

The idea of using carbon dioxide isn’t new. It was used to freeze off warts and skin tags, but didn’t get cold enough to do much more. The students figured a way to amp up the pressure on the carbon dioxide to drop the temperature further. “That’s what our intellectual property is centered on,” Surtees said.

Vets have been charging about $500 a procedure, about half the cost of traditional surgery, though both methods require the same evaluations, which can include biopsies and imaging. The tool itself costs vet clinics $8,000, and a carbon dioxide gas tank typically costs about $70.

To develop the tool, they worked with Nicholas Durr, an assistant professor and co-director of the undergraduate design team program in the Hopkins Department of Biomedical Engineering. He’s credited as a company cofounder and continues to advise Kubanda, as does the Pava Marie LaPere Center for Entrepreneurship that helps Hopkins students and alumni tap grants and lure investors.

Durr said development of the tool began with a discussion with a Hopkins doctor who said there was a need for technology to diagnose and treat breast cancer in Africa, where the disease can be a death sentence.

Durr said selling the tool to vet clinics now — 17 so far — made more sense than first trying to push through the costly and time-consuming, and often unsuccessful, process of human trials. Selling the device also provides revenue for human studies, though Kubanda will still need investors to get through the regulatory process set by the U.S. Food and Drug Administration.

He said elements other than carbon dioxide get colder, work faster and already are used in treating several types of cancers.

“We are interested in if the slower procedure would lead to better outcomes, if there is an additional immune response that helps in destroying a tumor or if there are other advantages,” said Durr, who came to Hopkins after launching his own start-up to increase access to eye care in developing countries.

In the meantime, pets are an immediate, multibillion-dollar market to tap, said Durr. Already, he considers the device a “huge success story” by students who began the work when they were 19 and just learning to be engineers.

Bishop said he expects to have a lot of patients who could benefit over time.

So far, he’s mostly used the tool on lipomas like Zlo’s that were big or oddly placed enough to cause problems. The tool can take care of smaller growths with one poke and larger ones with several. In Zlo’s case, Bishop opted for minimal intervention, a single poke that would likely shrink the lump by half, enough to restore his normal gait and comfort.

He asked the Kubanda team about setting up the system in his mobile treatment van so he could reach pets that can’t easily get to him.

“This lets me be more proactive,” he said about the tool. And that means he can give families more of what they really want from their pets: “Time.”