"You are the most gentle and tender creature I know, your sweet little essence ever soothing to my soul," he writes in a letter to his beloved pet, as part of a new book, A Letter to My Dog.
"I intended to write a letter thanking you for your unconditional love and unwavering loyalty," Vartan continues. "But instead, and I've given this a lot of thought, I'm writing to thank you for letting ME love YOU!"
The brainchild of photographer Robin Layton, the book stems from a blog of the same name, which asks dog lovers to submit photos of their pet and a letter to their animal. Animal enthusiasts Hilary Duff, Tony Bennett and Cat Cora have also contributed to the project, and you can too.
The site is accepting entries until December 15, at which point Layton will contact selected writers and photograph them alongside their pets for inclusion in the anthology. A portion of the book's proceeds will also benefit The Humane Society of the United States.