One example is Will, who was run over by a lorry, and left to die.
But he has found hope in the form of his caregiver, who has chosen to remain anonymous.
The caregiver, a member of Action for Singapore Dogs Society, said, "I saw that from his eyes he had this strong will to live... He's always a very happy dog despite his disabilities and the pain and all the injuries he's had, and I thought if humans have a second chance, why not the animals."
Although many stray dogs roam the streets, they aren't the only cause of dog overpopulation.
Deirdre Moss, Executive Officer of Society for Prevention of Cruelty to Animals (SPCA), said, "We get around 60-70 lost dogs every month. Most of these are pedigree dogs."
The overwhelming demand for adorable puppies has turned dogs into cash cows.
Jasmine is a victim of the commercial pet industry.
She was found outside a pet farm, and was probably rejected as a breeding dog because of skin problems.
Ricky Yeo, President, Action for Singapore Dogs Society, said, "The trend we're seeing is that people don't really bother as long as they're cutesy and nice, and if it serves their purpose, it's fine. But once there're problems and trouble like skin problems, injuries and all that, they basically just want to get rid of it."
Many dogs are "dumped" at the SPCA everyday.
But not all that end up there are in poor condition.
Some got lost, and remain unclaimed.
Many got dumped after the "cute puppy" stage, because of the heavy expense and responsibility needed for their upkeep.
Due to a lack of space and resources, the SPCA put down almost 2,000 dogs last year.
Ms Moss said, It's a matter of too many being given up everyday. And there're not enough homes. We can't find homes fast enough. And unfortunately not everybody can be selected for adoption as much as they deserve to be, and we wish they could be."
The message for potential dog owners is clear.
Mr Yeo said, "The point is to think carefully. Mentally and physically, you need to be prepared for a 10-15 year commitment."
Ms Moss added, "Before you buy a dog, please make sure you can keep it for the rest of its life. It's a big responsibility. It's not unlike having a child."
So before you find out how much is that doggie in the window, ask yourself: Are you ready for parenthood?