The driver first noticed smoke coming from his trailer just before 5 p.m. Monday, state police said. He pulled over, and the Lowell Fire Department put out the flames that engulfed the trailer, but they couldn't save the puppies.
The puppies were a variety of breeds between the ages of 8 and 12 weeks, according to a state police news release.
Neither the driver, identified as Joseph Price, 40, of Joplin, Mo., nor his passenger, William Iriarte, 50, of Nesho, Mo., was injured.
A preliminary investigation indicated that a malfunctioning fan in the rear of the trailer may have started the fire, police said. No charges have been filed.
The truck was owned by the Hunte Corp. of Goodman, Mo., a major puppy supplier for pet stores.
"The puppies were all beautiful, healthy purebreds that were on their way to quality retailers in the northeast and eventually to loving New England families," the company said in a statement. The company said it has a near-perfect safety record.