This is the adorable moment a girl from Napa, California broke down in tears of joy when she was given the surprise gift of a puppy.

According to the girl's mother, she had always wanted a dog but because of allergies in the family, they had never been able to get one.

After much pleading, the girl's mother finally agreed to get her a guinea pig when she returned from a school trip.

However, while the girl was on the trip, mum discovered some hypoallergenic puppies which were for sale and decided to buy one to surprise her daughter.

The emotional video begins when mum and daughter arrive at the pet store to pick up what the daughter still believes is a guinea pig.

The two browse a few accessories for guinea pigs and then, as they walk into the middle of the store, a woman approaches them holding a crate.

The daughter looks inside, sees a puppy rather than a guinea pig and bursts into tears of joy.

More tears flow as she cradles the adorable pooch and wonders out-loud "is this a dream?"

Although the video was filmed in 2016, it has only recently emerged online.