COUNCIL BLUFFS, Iowa — Not many people attend the races here at Bluffs Run Greyhound Park anymore. Aside from a few dozen aging diehards cheering the dogs from the shabby grandstand, the gambling-inclined prefer to take their chances amid the bright lights and constant action of the casino downstairs.

But even though the races are losing millions of dollars each year, the owners are required to keep the greyhounds running six days a week.

After a decade in which more than half the greyhound tracks in the country have closed, many of the remaining operations have survived thanks to the model used at Bluffs Run. Over the years, the tracks, which were there first, won permission from states to add slot machines and poker tables under the condition that a chunk of the profits go to the dog races — essentially subsidizing one form of gambling with another.

Now, after years defending greyhound racing against attacks that it is inhumane, a growing number of track owners are, to the astonishment of opponents and the dismay of fans, joining the critics among the animal rights groups. Complaining that they are being forced to spend millions of dollars a year to subsidize a pastime that the public has all but abandoned, greyhound track owners in Iowa, Florida and Arizona have been lobbying for changes in the law that would allow them to cut the number of races, or even shut down their tracks, while keeping their far more lucrative gambling operations.