Dan Gill / The New York TimesDr. Rebecca Smith operates on a dog with a cancerous leg at Blue Pearl, an emergency medical care facility for pets, in Overland Park, Kansas.

Judging by some of the heavy action in the world of biotechnology, one could easily conclude that the industry is going to the dogs. Or cats, maybe.

There are startups named Nexvet and VetDC, CanFel Therapeutics (as in canine and feline) and even Fetch Pharma.

It’s a new example of pack behavior: Entrepreneurs with pedigrees from companies such as Genentech and Amgen are turning their attention to pets. They hope to develop the same kinds of innovative drugs for dogs and cats that have revolutionized the treatment of diseases such as cancer and arthritis in people.

“We’ve been drugging ourselves for a long time, and more recently we’ve been drugging our kids,” said Oleg Nodelman, an investor in and director of Kindred Biosciences, one of the new companies. “Why shouldn’t our pets have access to medicine?”

They do already, of course. Many of the big pharmaceutical companies have long had veterinary drug divisions. Eli Lilly’s animal division, Elanco, for instance, sells the company’s Prozac antidepressant under the name Reconcile to treat canine separation anxiety.

But the new entrepreneurs say they will be more nimble and do what the big companies are not doing, just as the early human medicine biotech companies did.

The big companies focus more on livestock — edible animals as opposed to petable animals, said Dr. Steven St. Peter, chief executive of Aratana Therapeutics, a pet biotech company. Their offerings for pets are mainly vaccines and treatments for fleas, ticks and worms.

The new companies hope instead to treat diseases such as cancer and arthritis. Many are trying to develop monoclonal antibodies, which are proteins made in living cells. Such antibodies, like Humira for rheumatoid arthritis and Herceptin for breast cancer, are huge sellers in human medicine but have had almost no role in animal health.

“I was really a little struck by the fact that the biotechnology industry didn’t really participate in animal health at all,” said St. Peter, who was a life-sciences venture capitalist before co-founding Aratana. “There was this very large industry that was ripe for innovation.”

Investors seem to be biting, spurred in part by the interest generated by the huge initial public offering in early 2013 of Pfizer’s animal drug division, now called Zoetis. Since then both Aratana and Kindred have gone public, along with Phibro, which develops drugs for livestock, and Parnell, which sells livestock and pet drugs. Funds such as Adage Capital, Baupost, Fidelity and Wellington are investors in one or more pet drug companies.

The new companies say the time is right because people increasingly view pets as members of the family and are willing to spend thousands of dollars to treat a sick animal. Pets can get chemotherapy, knee surgery and transplants.

Americans spend “over $800 million on Valentine’s Day and $400 million on Halloween for their pets,” St. Peter said.

Americans spent nearly $56 billion on pets in 2013, up 45 percent from 2006, according to the American Pet Products Association. Of that amount, veterinary care, which includes prescription drugs, accounted for $14.4 billion, up more than 50 percent from 2006.

Moreover, there are drugs for people that can be adapted to treat the animal versions of diseases such as arthritis, cancer, obesity, diabetes, Alzheimer’s and various psychological problems.

Some experts, however, say the new companies, which have yet to commercialize any products, might be barking up the wrong tree.

“There are not a lot of unmet needs that are out there in the veterinary drug field,” said Bob Fountain of Fountain Agricounsel, a consulting firm in animal health. “Those who have tried to apply principles from the human market to animal health have had to have some lessons learned.”

One issue could be cost. Antibodies such as Herceptin and Humira cost tens of thousands of dollars a year. The pet drug executives say they can get the cost down to several thousand dollars a year, in part because pets need smaller doses.

But even that is likely to be too much for many consumers. Only a few percent of American pet owners have health insurance for their animals.

Even a big-selling animal drug might have sales of about $100 million a year, far less than the billions for a human blockbuster. But animal drugs can also be developed far more cheaply and quickly — for $10 million or less and in a few years, executives say.

In some cases, human drugs can be used directly in animals. But in other cases they cannot. For instance, some pain relievers, such as ibuprofen, cause severe side effects in cats.

Monoclonal antibodies developed for people would cause immune reactions if used in animals. Nexvet, a privately held Australian company that recently raised $31.5 million from U.S. investment funds, has a method to “peticize” antibodies, just as antibodies developed in mice are “humanized” for use in people.

In some cases, the entrepreneurs are motivated by illnesses to their own pets.

Dr. Jennie Mather, for instance, had just sold Raven Biotechnologies, a cancer antibody company she had founded, when her cat, Annie, died from gastric cancer that could not be treated.

“Here I was working to make cancer drugs with a process that could turn out dozens of possibilities a year,” she said. “And to go and be told, ‘Sorry, there is nothing we can do,’ it made me go and think hard.”

She started CanFel Therapeutics but was not able to raise money from venture capitalists.

“I could tell within two minutes if the (venture capitalist) had a pet or not,” she recalled. “If they did, they would listen. If they didn’t, they would look at me as if this person is totally insane.”

CanFel turned to crowdfunding but raised $16,800 out of the desired $87,000. But that was enough to buy lab equipment; the small staff is working without pay for now. Mather is hoping the reception that Aratana and Kindred have had on Wall Street will make it easier for CanFel to raise money once it has a candidate drug.

VetDC was founded to take advantage of another trend: Companies increasingly are testing their drugs on pets to get an early read on how the drug might work in people.

For instance, Gilead Sciences stopped work on a drug it was developing to treat lymphoma in people. But by then, studies had shown “beautiful data in people’s pets,” said Steven Roy, a former Amgen executive who runs VetDC. So VetDC is now developing that drug for lymphoma in dogs.

Some consolidation in the new industry has already begun. Aratana, which means “new” in Japanese, has acquired two other startups, Vet Therapeutics, which was developing antibodies, and Okapi, which was developing antiviral drugs.

Aratana has conditional regulatory approval for two antibodies to treat lymphoma in dogs. They have the same mechanisms of action as the human drugs Rituxan and Campath, respectively. Aratana plans to start marketing one of them in October.

If the startups succeed, it might not be too long before established biotech companies form their own animal divisions.