This dog's face realising the birthday cake was for him is the face of pure joy

This is the face of absolute joy. Photo / Reddit/ARealRocknRolla

This is the exact moment this dog realised the birthday cake was for him.

Reddit user ARealRocknRolla posted the photo of his co-worker's dog, showing the exact moment the dog realised it was his cake.

Photo / Reddit/ARealRocknRolla

Apollo received a bone-shaped cake for his birthday and it is easy to see why the photo of his reaction is going viral.

In just one day, the post received more than 18,000 upvotes on Reddit, with hundreds of comments about the dog's happiness.

Happy birthday from New Zealand, Apollo!