More than three years since production problems pushed Interceptor off the market and its manufacturer then canceled the brand, the popular pet parasiticide is coming back.

Under the new ownership of Elanco Animal Health, a division of Eli Lilly and Co., the once-a-month tablet made to protect dogs and cats against heartworms and intestinal worms will be available this spring, the company announced Monday.

The reintroduction reverses a decision in 2013 by Novartis Animal Health, the originator of Interceptor Flavor Tabs. Eli Lilly bought Novartis Animal Health in a transaction that closed on Jan. 1.

In a news release, Elanco called Interceptor “the heartworm protection trusted by more veterinarians for their own dogs for over 20 years” and said its return is spurred by popular demand.

The formulation will be the same as before, according to company spokeswoman Colleen Parr Dekker. The active ingredient in Interceptor is milbemycin oxime. The drug is designed to protect dogs from whipworms, roundworms, hookworms and heartworms; and cats and kittens from adult roundworms, hookworms and heartworms.

Exactly when Interceptor will be back depends upon the U.S. Food and Drug Administration, Parr Dekker said in an interview by email. Elanco anticipates the action by early spring. “In fact, launch quantities of Interceptor Flavor Tabs have already been produced and are ready for shipment following release,” she said.

Dr. Beverly Brimacomb, a veterinarian in Lakeland, Florida, called the announcement about Interceptor “the best news I’ve heard in a long time.” Brimacomb said she's repeatedly urged Elanco representatives to revive the anti-worm drug.

A practice owner and one-time breeder, Brimacomb said she found Interceptor to be a particularly effective agent against intestinal worms in her region and more affordable than other oral anti-heartworm products.

One such heartworm preventive is Trifexis, made by Elanco. “Trifexis is massively expensive,” Brimacomb said, on the order of $25 per month compared with $4 or $5 a month for Interceptor.

Whether Elanco will sell Interceptor at its former price is unclear. Parr Dekker did not have an immediate answer about pricing.

Trifexis is designed to do more than Interceptor — it targets fleas as well as heartworms and intestinal worms. But depending on the situation, veterinarians may recommend something else for flea control. In fact, the options for controlling parasites on dogs and cats are broad and expanding to a bewildering degree. There are pills, soft chews, solutions applied to the skin, and collars; products for dogs only, cats only and both; and products that work against just one type of parasite, a few types of parasites or an array of parasites.

Choosing the best product or combination of products involves considering factors including pet species and breed, types of parasites prevalent where the pet lives, pet and owner lifestyles and owner preferences.

The return of Interceptor is the latest chapter in a tumultuous history for Novartis pet parasiticides. The products were casualties of manufacturing problems that lasted for 16 months starting in late 2011. The loss of the parasiticides Interceptor, Sentinel Flavor Tabs and Sentinel Spectrum, among other animal drugs, caused consternation among veterinarians that was compounded by poor communications by Novartis.

When production resumed in spring 2013, Novartis discontinued Interceptor but kept the Sentinel line. Like Interceptor, Sentinel contains milbemycin oxime. Sentinel Flavor Tabs contain lufenuron, as well, to control fleas. Sentinel Spectrum has the same ingredients as Flavor Tabs plus praziquantel to target tapeworms.

During the manufacturing hiatus, veterinarians and pet owners who used Sentinel or Interceptor were compelled to switch to competing parasiticides. When Sentinel returned to market, some stayed with the products they’d switched to, while others welcomed it back.

Dr. Steven Hornstein, a practice owner in Monroe Township, New Jersey, is among those who were glad to see it back. He’d been a big user of Interceptor, but didn’t mind going with Sentinel. “I consider them almost interchangeable,” he said.

During the period when neither was available, he switched to Trifexis but found it to be a less-than-ideal substitute, Hornstein said, for these reasons:

First, it was significantly more expensive. Second, although it costs more, Trifexis doesn’t protect against ticks. Ticks being a big problem in his region, pet owners had to buy something else for that. And third, Trifexis is dogged by persistent rumors, mostly purveyed on the Internet, that it’s unsafe.

“Whether it’s true or not, it becomes reality,” Hornstein said. Given its reputation, it’s simpler to avoid Trifexis if possible, he said.

Asked whether public doubts about Trifexis influenced Elanco’s decision to offer Interceptor as a second heartworm preventive, Parr Dekker, the company spokeswoman, replied only: “Trifexis continues to be a leading choice for veterinarians and pet owners. We are pleased to be able to provide a full portfolio of parasiticide products to complement any clinic recommendation or client need.”

(In acquiring Novartis Animal Health, Elanco did not acquire Sentinel. The line was sold to a third company, Virbac Corp.)

With Interceptor on its way back, Hornstein hasn’t decided whether he’ll drop Sentinel in favor of Interceptor. “I’d be curious to see what the prices are going to be for both,” he said. “I may make a recommendation to clients based on that.”

Then again, he may go with something else. From the dynamic realm of pet parasiticides, Hornstein said he expects to see yet another form of protection become available soon: a tablet that kills fleas, ticks and heartworm, which would fully cover at least some of his patients’ needs for parasite protection.