When this 2-year-old pup got herself stranded in the chilly waters of New York's East River, a heroic man abandoned his own birthday party so he could swim to her rescue.

The incident took place last week in Brooklyn when Harper the dog was out on a stroll with her petsitter.

As they were walking down the street, the petsitter was suddenly hit by a taxi that had run through a stop sign. Though the petsitter only sustained minor injuries, Harper took off in a panic and charged into the river.

Meanwhile, Gabe Castellanos had been celebrating his birthday with some friends on the Brooklyn Barge when they saw the dog in the water. Since it was a warm day, the group assumed that the dog was simply going for a swim while its owner watched from the shore.

As the dog swam farther and farther away from the pier, however, the dogwalker suddenly approached the group and said that Harper had run away.

Castellanos noticed that Harper was quickly losing steam and he knew that he had to do something; luckily, Castellanos is a graduate from the SUNY Maritime College.

Using his maritime experience, Castellanos grabbed a nearby lifejacket, stripped down to his underwear, climbed out to a safe part of the pier, and plunged into the water.

With dozens of pedestrians cheering him on from the shoreline and a police helicopter flying overhead, Castellanos swam out to Harper. She had already been paddling for over ten minutes, and when she caught sight of Castellanos heading towards her, she started to swim even more determinedly.

Castellanos eventually managed to catch up to her and start steering her back towards land – but unfortunately, since Harper was so panicked by the experience, she bit Castellanos on the hand and face, chipping his tooth in the process.

Unfazed by the attack, Castellanos continued guiding her back to the shore until she was finally reunited with her emotional petsitter.

Even though Harper's attack forced Castellanos to get a temporary fake front tooth, he later expressed his sympathy for the dog and said there were no hard feelings between them.

"I was like, ‘Aw it's alright, I needed teeth work anyway,'" he told Inside Edition.

Harper's owner has expressed her bottomless gratitude for Castellanos's actions and she says she hopes to throw him another birthday party as a thank you for the rescue.

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