The unforgettable images that show love in its purest form.

Photographer Eva Hagel is giving people one of the most precious memories possible: an image of them with their much-loved, dying pet.

The Minnesota-based photographer said  passing of her dog Cleo "was the most traumatic moment of my life".

"Having these images to look back on can help begin the healing process and encourage memories about what a joy their companion was."

A pitbull named Hector is the subject of one series of images.

He was rescued in 2007 from NFL quarterback Michael Vick's dog fighting ring. His new owners, Roo and Clara Yori, lifted awareness about dog fighting rings by creating a Facebook page for Hector.

In late 2014, Hector was diagnosed with cancer. The Yoris reached out to Hagel to capture one of their last outings with their dog.

When Hagel uploaded the photo's of Hector to her Facebook page, she wrote:

"I never want a Project Cleo session to be sad. Yes, they are emotional, but it should be a celebration of life! A celebration of the journey you and your beloved pet have taken together! I love capturing these happy moments, as I know they will last a lifetime in memories."

However some photos can't help but be a heartbreaking.

Like these:

And these:

But they are all beautiful:

Hagel's business runs off donations. You can find out how to donate here and more about Project Cleo here.