When Mark Imhof adopted his first dog from a New York City shelter and gave it a bath, he said so much dirt came off he couldn't understand where it was all coming from.

"I remember my fiance and I saying, 'Wouldn't it be great if someone could come to shelters to groom these dogs?'" he said.

And that's exactly what he's doing now.

Imhof, also know as 'Mark the Dog Guy,' left his accounting life last year and started a business that provides pet services like grooming and walking.

But at shelters, he volunteers time to primp pups for free.

Imhof said he noticed that many shelters didn't have the time or the resources to groom their rescue dogs, making it harder for the pups to be adopted.

"The first dog I cleaned was mean and scared me to be honest. But it turned out it's just because these dogs are in pain. Their fur is knotted and it's uncomfortable for them. But as soon as I'm done, they're jumping up and down and kissing me because they feel so much better."

Imhof said his fiance encouraged him to launch his pet service business after attending the American Academy of Pet Grooming School in Manhattan last April, and adopting two shelter dogs.

"They're more friendly after and you can see their eyes. That's how you make them more adoptable and that's the goal here."  

Imhof said almost all the dogs he's groomed have been adopted.

"Nothing is more rewarding than knowing these dogs get their forever home."