Published: Sep 18, 2012 4:54 PM EDT

It's a picture that has changed the life of a Wisconsin man and his dog. Now, there's a new chapter to the story that touched hearts across the world.

John Unger and his dog, Schoep, float together in Lake Superior to relieve the aging dog's arthritic joints, but the picture has led to a healing no one expected.

Unger has received an outpouring of cards, artwork, gifts and money to help his dog. One woman from California even sent a Tempurpedic dog bed.

At 19, the years have slowed his Shepard mix, but lately, Unger has noticed some subtle changes and signs of a younger Schoep returning.

One man in Connecticut donated supplements to the dog's veterinarian. Another person donated three times over three days. Correspondence came from all over the world, from those who aren't ready for an 18-year partnership to end.

Unger said without treatment, it was time to say goodbye to Schoep. The money, that has now topped $10,000, pays for a weekly laser therapy to stimulate old cells in Schoep's body. The results are almost immediate. Unger said in the five weeks they've been doing these treatments, the dog has been able to pick up his walking pace.

In the weightless water of Lake Superior, Unger and Schoep still find a few moments peace, even though the weight of what's to come weighs heavily on Unger's mind.

With donations still coming in, the cost of Schoep's care will be covered for the rest of his life. Any remaining money will be used to start Schoep's Legacy Foundation, a program to help other animals in need.