Dozens of passing motorists tooted their horns in support as the animal lovers lined the roadside with placards bearing messages such as 'Stop the killing'.
The demonstration, attended by a range of ages from pensioners to children, was organised by international charity Greyhound Action following claims in a national newspaper that staff at the sanctuary offered to put down two healthy young greyhounds for £70. Thousands of former racing greyhounds as young as two are destroyed each year when they are no longer fast enough on the tracks.
Demonstrators were also protesting at other animals put down at the sanctuary.
Former employees of LAS last week claimed the sanctuary was purely a money making venture and a "slaughterhouse" where large numbers of healthy cats, dogs and rabbits were put to sleep on a regular basis, to free up kennels for more animals to be brought in.
During the event a minute's silence was observed in memory of all the animals put down at LAS.
Some demonstrators had travelled from as far as Scotland and Birmingham and many brought their own rescued greyhounds. Alexia Smethurst, 36, and her partner John Harney, 37, travelled from Leeds with their two rescue greyhounds, Lucy and Eric.
Alexia said: "Its estimated 30,000 greyhounds are put down or disappear every year. Places like this make it so easy for racing dogs to be got rid of no questions asked.
"Racing greyhounds are retired from as young as two, but can live to 15. Both our dogs were dumped on the street."
One local animal rescue worker, who asked not to be named, said: "Fifty per cent of cats, dogs and rabbits which go into LAS never make it out again apart from in a bodybag.
"We have all known what has been going on at LAS for a long time and have lobbied Wigan Council, but have been ignored. "
Karen Taker, 50, of Carr Street, Leigh, said: "I bought a dog from here which was completely out of control and kept ripping everything up in my house.
"I brought it back because I couldn't cope with it but after hearing what goes on at LAS I went back a week later to take the dog back because I was concerned it would be put down. It wasn't there. They told me it had been re-homed, but I don't believe it."
Caroline Seddon, 26, of Plank Lane, Leigh, added: "My brother got a dog from here. They just handed it over to him straight away no questions asked. I'm shocked they don't do any home checks. People could be taking dogs for fighting or anything. They just want the money."
Sonia Hillidge, 36, from Leigh was at the protest with her two-year-old daughter Summer. She said: "I have been involved with animal welfare groups and rescue groups over the years and have heard more and more about the sanctuary.
"Things like dogs being put down if they are not cute enough. I'm really pleased that people are doing something about it at last."
LAS owner, Linda Buxton has repeatedly refused to be interviewed.
Bosses at LAS recently issued a statement claiming animals are only put to sleep "when every other avenue has been explored and there is no viable alternative."