Engineer and ground worker Jonathan Halstead, 35, was bitten in the neck by his Staffordshire Bull Terrier and Mastiff cross Bronson after falling unconscious in his bedroom.
The canine was shot dead by police and the "proud family man" of Oldham, Greater Manchester, was pronounced dead at the scene.
An inquest heard his dad, medics and police were unable to get into the room due to his dog's aggression on January 29.
The coroner concluded he died as a result of wounds inflicted by the dog after a seizure rendered him unconscious, Manchester Evening News reports.
Heartbroken Stephen Halstead said his son had been diagnosed with epilepsy aged 11 in 1998 and had periods where he would suffer a seizure a week.
The hearing was told Bronson was bought as a puppy seven years ago and had a "soft temperament".
But it had previously become "agitated" and "overprotective" when his owner suffered seizures, it was heard.
In 2018 he attacked the family's other dog, a female called Sasha, who had to be put down as a result of injuries she sustained.
Mr Halstead, who lived with his son in Duckworth Street, Shaw, described him as a "proud family man" who was "full of energy and fun".
He said he had seemed "happy" and "full of joy" on the day he died.
He said after waking up around 1pm and having a sandwich, Jonathan went for a shower and Bronson followed him upstairs as he was "like his shadow."
"I just heard a tremendous bang," Mr Halstead told the hearing.
"I knew he had had a fit but I think I knew there was something different about it.
"Because when Jonathan had one of his fits, inevitably he tended to crumple down and never seemed to hurt himself terribly badly.
"This was very different, it was a very loud bang."
He said when he went to see what had happened Jonathan was lying still on the floor and but he was having no visible convulsions.
"There were none of the other usual signs as with a normal epileptic fit. It was a different sort of event," he said.
He said during previous seizures Bronson would "bark at him and try to get a response from him".
"On this occasion he seemed unusually protective of him", he said adding "it was as if he was trying to drag him under he bed".
"It was unusual I couldn't get him away. He just showed aggression if you tried to move into the room.
"He was being very protective, he wouldn't let anyone near him."
Detective Inspector Kenneth Blain from Greater Manchester Police (GMP) said officers who arrived had tried to distract the dog with food and commands.
But eventually the decision was made to call in a firearms officer and Bronson was shot dead so medics could attend to Jonathan.
DI Blain said in February 2018 Mr Halstead's other dog, a female called Sasha, had been put down after suffering injuries in an attack by Bronson following a seizure.
The vets who carried out the procedure were under no obligation to report the matter to the police unless they deemed the dog was a wider threat to the public, which they hadn't, he said.
He also confirmed Bronson was not a pitbull type dog and as such was not a banned breed under the Dangerous Dogs Act.
"I don't think he wanted to hurt Jonathan," Mr Halstead said.
"My feeling is that he was already dead, that's the truth of how I see it."
However a pathologist said the fact it was "implausible" that Jonathan had suffered a sudden unexplained death in epilepsy.
He said the fact he suffered bruising and the extent of the bleeding from his wounds, on the neck, chest and cheek, several of which were large and deep, suggested he had "maintained circulation" and was alive at the time of the attack.
He added the injuries sustained were "incompatible with life."
The medical cause of death of death was recorded as 1A) severe neck injury as a result of 1B) dog bites and 1C) epilepsy.
Senior coroner Joanne Kearsley told Stephen Halstead: "I can fully understand your questions around what was the medical cause of death.
"We know he had a history of epilepsy and know he suffered from seizures on and off.
"I can fully understand your questions given what happened here and given that this seemed to be a different type of seizure.
"Having heard the medical evidence, I accept on the balance of probabilities that the actual immediate cause of his death was the injuries he sustained, particularly the severe neck injury, following the attack from Bronson.
"I understand you think he was just being protective of Jonathan.
"But we know previously when having a seizure he may have shown some aggression and been overprotective with him."
She recorded a narrative conclusion that he "died as a result of injuries sustained in an attack from his dog, whilst unconscious following an epileptic seizure".