More than two years after Merck stopped manufacturing Vetsulin due to sterility and stability concerns, the company has reintroduced the product to the U.S. veterinary market.

The return of the only FDA-approved insulin product for dogs and cats gives veterinarians another tool as they work to manage the ever-growing diabetes problem that has been consistently growing in the U.S., a company spokesman said in a news release from Merck. 

"We are pleased that Vetsulin is again available in the U.S. market; offering our customers the same product benefits that veterinarians worldwide have relied on for the past 20 years," said Christopher Pappas, DVM, director of technical services at Merck Animal Health. "At Merck Animal Health, we are committed to providing our full support to veterinarians as they manage the health of dogs and cats living with diabetes."

According to the Vetsulin website, Merck stopped manufacturing the product because of testing that showed the "amount of crystalline component within batches of Vetsulin had risen above specification at some point in the shelf life."

The manufacturing concerns have now reportedly been resolved, and the new formula is largely unchanged compared to the previous version, the company said.

"The only difference is a slight change in the proportion of the short-acting amorphous fraction and long-acting crystalline fraction of Vetsulin. The short-acting amorphous fraction is now 35% (formerly 30%) and the long-acting crystalline fraction is now 65% (formerly 70%)," the company explained.