If you have a dog, you have certainly found the sweet spot on their belly.  And you might have noticed that every time you scratch that particular spot, your pooch kicks their legs – but have you ever wondered why?

Although many owners think that this dog kicking is a sign of happiness, this reaction is in fact a means of self-protection for your pup. The scratch reflex is an involuntary response that exist to keep your dog safe, according to Animal Planet.

‘’Dogs shake or kick their legs when you scratch them because of something known as the scratch reflex. It’s a completely involuntary reaction, which explains why your dog may look as puzzled as you do when it starts to happen. When you scratch or tickle your dog’s belly, it irritates him, much the same way that the wind or a bug might. It activates nerves under his skin that are connected to his spinal cord and relays a message to his leg muscles to kick in an attempt to get rid of the irritant. Of course, you’re the one both providing the “itch” and “scratching” it, so it’s a completely pointless act.’’

Also, those kicks are similar to human reflexes, according to Dr. Lore Haug, a veterinarian and animal behavior expert for Texas Veterinary Behavior Services.

“Let’s say you touch a hot stove, and before your brain recognizes it’s painful, the spinal cord recognizes the pain, and you involuntarily jerk your hand back. If you had to wait until your conscious brain recognized something was in danger, your delay in reaction time could cause an injury or even death in some cases.”

You should also know that veterinarians use the sweet spot to locate nerve damage or neurological problems in dogs – a bit like how doctors test the knee-jerk reflex using a rubber hammer.