Sleeping next to a dog leads to asthma and dermatitis.

The blame lies with the animal's fur and dander, which trigger an allergic reaction. Doctors explain that when you inhale particles of animal dander into your lungs, your body's immune cells recognize the dog's antigen as a foreign substance posing a threat to your health. As a result, an inflammatory reaction begins, releasing histamine, which causes smooth muscle contraction and airway narrowing. This means you cannot get the necessary amount of air into your lungs. Besides this, dog dander can cause allergic rhinitis, dermatitis, and hives.