You always hear that dogs are man's best friend...but some dogs are lifesavers.
Gwathmey suffers from daily seizures and severe Post-Traumatic Stress disorder.
"He was in such a deep, dark place that we couldn't reach him anymore," says wife Carolyn, who didn't know what to do.
"I was contemplating suicide, not knowing what was going on," Gwathmey admits.
Then a veteran of another war came to the rescue.
"I like helping people. I really do," says World War II veteran Irwin Stovroff who was shot down over Germany in 1944. He survived a year in a prisoner of war camp and came home. He was highly decorated, even receiving the Distinguished Flying Cross.
Four years ago he started a program called Vets Helping Heroes, which finances training for service dogs that help disabled veterans.
A Labrador mix named Larry was sent to Gwathmey to improve his life.
"He gave Mark just that little extra love that he needed and that extra attention that he needed," Carolyn says.
The dog can tell when his master is in trouble. Mark acted out a seizure to illustrate how Larry runs to his side and makes sure he is okay.
Home video of Gwathmey suffering an actual seizure shows Larry licking his face until he came out of it.
Heroes from past wars are working to help today's war heroes.
For more information about Vets Helping Heroes, go to vetshelpingheroes.org/.