Research has found that there are two types of tickles. Gargalesis is when certain areas of the body deemed to be ticklish are touched and thus invokes laughter. These areas are generally the neck, feet, armpit, stomach etc. The other kind of tickle is called the Knismesis. This is caused by light motion of the skin. But this kind of tickle doesn’t bring on laughter.
Dogs are incapable of Knismesis tickle because they have fur which covers the skin. Dogs are incapable of Gargalesis tickle because they do not possess the tickle receptors as us humans do. When you scratch any area of the dog that you think will tickle it, you will notice that the animal simple gets comfortable and may even end up sleeping in your arms. Rubbing the dogs underarm, belly, or neck simply creates a comfortable and pleasurious feeling to the animal.
The next reason why dogs are not ticklish is because dogs cannot laugh. Laughter is an emotion which is sacred to us humans no matter the race or color.
Well, if for some strange reason you scratch under your dog's tummy and you hear your dog begins to laugh hysterically, chances are that you are that special dog owner whose dog is ticklish. So don't let the science of being tickled stop you from scratching your dog's tummy or behind the ear. Chances are even if the dog is not tickled, it really feels good to him or her. So go ahead, go tickle your dog.