U.S. and Colombian officials have arrested 22 Colombians for smuggling heroin into the United States using a wide variety of methods, including having the drug surgically implanted into puppies.

U.S. Drug Enforcement Administration officials said Wednesday that a two-year investigation led to the arrests in Colombia and the United States.

Officials said that in one instance, three kilograms of liquid heroin packets had been implanted into six puppies. Three of the dogs later died of infection.

DEA officials also say smugglers frequently use human couriers, known as "swallowers," who typically ingest drug-packed pellets before boarding flights for the United States.

The drugs are also frequently concealed in body creams and aerosol cans, and sewn into purses and luggage.

Some information for this report was provided by AP and Reuters.