Typically, hair is longer, thicker and smoother than fur. It grows less densely. Hair can be curly, wavy, or straight. The curly hair is the type that usually ends up trapping dander that can trigger an allergy.

The dog breeds that have hair feature only one single layer. According to the American Kennel Club, thirty-six dog breeds have hair instead of fur.

Fur is usually much shorter than hair and a lot denser. Its growth cycle is much faster, and it sheds significantly more than hair. That contributes to larger concentrations of dander.

The dog breeds that have fur feature two layers – an undercoat and a topcoat.