There's no doubt that Sylvester Stallone is one of Hollywood's most successful actors. After decades of making movies, the 70-year-old has a list of huge series to his name, including the Rambo, Rocky and Expendables films.

But there was a time when he was just a young, aspiring actor living in New York city, and he shared a memory of that part of his life with his Instagram followers on Friday.

Stallone writes that he was "26, totally broke, going nowhere VERY fast, owned two pairs of pants that barely fit, shoes that had holes in them and dreams of being successful were as far away as the sun...But I had my dog."

Stallone explains that his dog Butkus - named after football player Dick Butkus - was his best friend and confidant, who "always laughed at my jokes" and lifted his spirits while he was trying to sell his first screenplay.

At the time Stallone was living in a small apartment above a subway station, and Butkus was his only distraction from work.

The actor even jokes that it was "his idea" to write Rocky.

Sadly, with no money to pay for food Stallone was actually forced to sell Butkus for $40.

It was a hearbreaking moment for Stallone, but luckily he sold the screenplay for Rocky soon after, and he was able to buy his beloved dog back.

His new owner tried to push his luck by selling the dog for $15,000, but Stallone happily paid, writing that Butkus was "worth every penny!"

Stallone repaid his dog for all the support he had given the actor throughout the years. He was given a role in the first two Rocky movies and flew first class with Stallone wherever he went.

Sadly, Stallone revealed in an interview that Butkus died in 1981, just a few years after his owner became a Hollywood success story.

But Stallone never forgot the love his dog showed him. He even shared that he still uses Butkus's picture as his computer wallpaper.

Stallone's story proves the one thing all dog owner's know: their pet will stick with them through thick and thin.

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