Some animal lovers said they were frustrated this weekend when they showed up to the North Texas Humane Society in Fort Worth to give homes to dogs dumped in Flower Mound and Sanger last week.
This weekend more than 300 people lined up in Fort Worth to pick up one of the puppies.
Some said they had been waiting since midnight because they were told adoptions would be first come, first serve, but at the last minute the shelter decided to use a lottery system to give each dog a home.
The shelter said while usually it is a first come, first served shelter, when it comes to popular dogs they use a lottery system.
One woman drove all the way from Midland.
"We waited in line, and then it turned out the line didn't mean anything. They're going to go through the applications and find out who to give them to so, I don't know," said Sue Smith. "I think the fact that I drove over 350 miles should give me some brownie points, don't you?"
The HSNT said Monday that each of the 21 dogs available for adoption this weekend was assigned a new home. More dogs could be ready for adoption soon.
The Humane Society is offering a $500 reward for information on who dumped the dogs, and In Defense of Animals, an international animal protection organization, has offered a $2,500 reward for information leading to the arrest and conviction of whomever abandoned the dogs.
Police in Flower Mound found 51 Maltese mixed-breed dogs along a country road near Highway 377 and Stonecrest Road. And 41 dogs -- mostly Cavalier King spaniels -- were found along a rural road near Sanger.
HSNT believes both cases are related and probably the work of puppy mill operators who no longer want to breed the animals under a strict new state law.
Anyone interested in adopting the dogs can contact the Humane Society of North Texas in Fort Worth at 817-332-HSNT or the city animal shelter in Flower Mound at 972-874-6390.
NBC 5's Andrew Tanielian contributed to this report.