Firefighters shifted the grill while the cubs' distressed mother howled and barked for them from her nearby den but they had no tools to cut through it.
Eventually an animal rescue worker tried the washing-up liquid and managed to free all three, who were then released near their home den and scarpered back to mum.
An unnamed boy riding past on his bike discovered the stranded pups in Plainfield, Connecticut, US, and called police.
Animal Control Officer Karen Stone called the firefighters for help but when they were unable to free the cubs, she tried oiling their heads Vaseline and then corn oil.
But it was only when she soaped their heads in washing-up liquid - and ignored their attempts to bite through her gloved hands - that she was able to slide them through the grate.
Mrs Stone said she then put the cubs in a dog crate and drove them towards their den before releasing them back into the wild.
She said she now drives by regularly to check the grate in case they get stuck again.
"Except for being a little soapy, I think they were OK," she said.
"Hopefully, they learned their lesson."
It is not known how the cubs got stuck but it is possible they were chasing a mouse, which was found dead near to the grate.
