How can a dog lose its hair in spring?

You can take some pictures of dog hair with some words.

There are several reasons for hair loss, and it is too greasy to eat. Second, it's too salty. The third is seasonal. It's almost summer now, and dogs have to change the down inside, so summer won't be so hard for them. If your dog's hair is normal and seasonal, it's okay, and so is my family.