"I looked off to my right, and there he was, just standing there, staring at me.
"At first, I wasn't intimidated," she added. "I thought, 'Wow. This is really cool. Look at that cougar.'
"Then I thought, 'Wait a minute, that's a cougar.'"
Perhaps rather unwisely, she initially decided to try to film the animal as it approached, before appreciating the danger she – and Murphy – faced.
The chances of escaping a cougar, which can run at 50 mph, are pretty slim.
Gallant hoped to intimidate the beast by waving her arms and shouting, but to no avail as the cougar continued heading towards her.
Then inspiration struck.
She scoured through her iPhone's music library and played the heavy rock classic – which was once named as one of the 50 greatest conservative rock songs – at full blast.
"I thought it was perfect because it gives him the message that I want to send, and it's a really intimidating-sounding song.
"I immediately put it on and I held it up high in the air," she continued. "As soon as he heard the first note, he bolted. He was just gone."
On average six attacks by cougars, also known as mountain lions or catamounts, are reported in North America a year – of which only one is fatal.