After a successful business career in one of the world’s leading consulting firms, Mark Tillinger was diagnosed with cancer along with his best friend and companion, Riedel, a 5-year-old Bermese Mountain Dog. The two battled the disease side by side, clinging to each other for strength and comfort even when things seemed hopeless.

Tillinger survived his bout with cancer. Riedel, unfortunately, did not. At the same time, David Duchemin, part-owner of the Veterinary Cancer Center in Norwalk, Conn., where Riedel had been aggressively treated over an 18-month period, lost his 12-year-old Rottweiler, Cody, to cancer as well.

Today, Tillinger and Duchemin work together leading The Riedel & Cody Fund, a non-profit organization founded in loving memory of their lost companions.

"I envisioned this organization that we built that fundamentally was designed to help people who were going through the same circumstance that I was going through with Riedel," Tillinger said.

"We provide funding, support and resources for people whose pets have been diagnosed with cancer."

Riedel and Cody’s stories are heartbreaking, but they are by no means uncommon.

As pets’ life expectancies creep ever upward alongside humans’ thanks to constant medical and health-related advances, they become increasingly susceptible to cancer. It is the leading cause of death in dogs older than 10, half of whom suffer with the disease; 12 million dogs and cats die of cancer per year.

These figures, disproportionately high compared to humans, translate into expensive, painful and often tragic experiences for those whose pets are afflicted. That’s where the Riedel & Cody Fund comes in.

"Many people can’t afford treatment and are forced to face the decision of having to put their dog down or not treat the dog because of lack of resources," Tillinger said, "so my idea was to create an organization that provided funding to those people who couldn’t afford it."

The Riedel & Cody Fund provides both direct, non-repayable financial aid to low-income families whose pets are suffering as well as dollar-for-dollar programs that match funds that applicants raise individually. In 2011 alone, it shelled out more than $430,000 to pay for pet cancer treatments.

But money isn’t everything.

"I think the bigger aspect of what we do is the emotional support that our community gives each other," Tillinger said. "Other pet-owners who have gone through it give more of the human side, which goes a long way to turning the fear, sadness, and anger into more positive emotions."

That sense of community support comes in part from nationwide events put on by the Riedel & Cody Fund. The ongoing "12 Million Dog March" brings families, friends and pet-lovers together in order to raise money and awareness to combat the epidemic of cancer in dogs and cats.

The march features activities like palm-readings for dogs, pet caricatures and musical performances. Spanning a roughly two-year period, it started in Los Angeles last summer and has events set in Chicago and Atlanta throughout the coming year, all of which are linked by the online, virtual march.

Signups for the virtual march can be found at www.riedelcody.org, and the Blue Buffalo pet food company — one of the march’s sponsors — has pledged to donate $1 to the cause for every attendee who signs up.

But you don’t have to be a pet-owner to understand the types of bonds shared between friends like Tillinger and Riedel, Duchemin and Cody, and countless others.

Said Tillinger: "Riedel and Cody changed our lives and we started The Riedel & Cody Fund so that their legacy can change the world. And we really and truly believe in that."