Photographs of March, a pit mix, show the canine in the depths of depression.
Living in animal rescue shelter ACCT in Philadelphia, Pennsylvania, since he was brought in as a stray, the dog was finally due to be rescued.
But at the last minute, his new family pulled out of the deal and March was taken back to the shelter, media reports said.
Since then, March has spent his days facing the plain grey wall in his kennel, and interest in him has sharply declined.
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A Fox News reporter, who witnessed March's dejection first hand, posted on Facebook: "This boy thought he was about to embark on a better life, only to be returned to the scary Philadelphia city shelter.
"Sadly, he has barely gotten any notice, and he is getting depressed and sick now.
"He was such a happy boy, but shelter life is taking a toll on him."
Described as a 'handsome' dog by volunteers, a fund has now been set up by sympathisers to find March a home.
Already raising USD 709 in just over a day, organisers hope this will be the boost March needs, the reports said.