Since birth, Dylan has been in a persistent vegetative state - but Tascha has been there for the boy from Schönwalde-Glien in Brandenburg. Videos show the six-year-old American Staffordshire terrier tenderly licking Dylan's hand and resting her head on his arm.
But she is officially considered dangerous by authorities in Brandenburg where she lives who want to take her away from the family.
Dylan is kept alive by a life-support machine but, like other patients with his condition, he occasionally opens his eyes - although when he does he is only partially conscious, according to doctors.
"When Tascha lies by him, the boy becomes much calmer and his pulse and breathing relax," said his father Eckhard Gerzmehle.
The family bought the dog as a puppy when they lived in Berlin and at first nobody knew what breed she was. When this became clear her owners applied for a dog license.
Things went wrong when the family moved from Berlin to Brandenburg two years ago and Tascha later bit and injured another dog. She is now deemed dangerous by Brandenburg's authorities.
According to the Dog Owners' Act she must now be taken from the family and, if necessary, impounded.
But opposition to her confiscation has been building online after a story appeared earlier this week in the BZ newspaper and now there is hope that the friends will be allowed to stay together.When Berlin fireman Jürgen Töpfer read the story, he spontaneously launched a Facebook campaign to prevent Tascha's removal.
The 48-year-old began the campaign a week ago and by Friday lunchtime it had almost 106,000 likes on Facebook. "I'm overwhelmed," said Töpfer who has children of his own.
Since the page was translated into English it has also received backing from people in Britain, the United States and countries in Asia.
The Erna Graf Institute for animal protection has also offered the family its support. Chairman Eisenhard von Löper hopes the authorities will see sense. "The boy needs Tascha," he emphasized.
Schönewalde-Glien's mayor, Bodo Oehme warned there was no room for negotiation where the Dog Owners' Act is concerned. But he said that sometimes exceptions can be made, for example in cases involving dogs for blind and disabled people.
Oehme has been in contact with the family and is waiting to hear back from them over a possible way forward. "The decision over Tascha's future will then soon be reached," he said.