Dogs have feelings, too, and respond to certain stressful situations by trembling, shaking, or shivering. It could be that he's happy (Yay! You're home from work!), or it could signal fear or stress.
Barking is common in shelters and boarding kennels for exactly these reasons. Dogs are pack animals that, by nature, will try to seek comfort or a playmate if they are lonely or bored.
We all love a cooling summer rainstorm, but thunderstorms can be very stressful for dogs. Why? Because loud noises and changes in barometric pressure are felt differently by dogs than humans, and dogs with noise phobias tend to suffer the most.
Dogs are social creatures and like to be with a group. If your dog is not sick, but he's hiding in a corner, under the bed, or behind the furniture, chances are he's stressed out.
Because dogs are social animals, puppies may become very attached to you or someone in your family, following you around the house, and becoming increasingly upset if they can't be near you at all times.
Dogs are social animals, and don't like to be left behind — either from the pack of dogs (despite being domesticated, this is their natural instinct) or their new pack of humans.
Panting is a normal function for dogs. It's how a dog cools down and settles his breathing after exercise or being outside in the heat. Dogs also sometimes pant when they are nervous.
Whether it's from improper socialization as a puppy or negative experiences prior to him joining your family, cowering (crouching down in fear) is something to be concerned about.
Dogs may bark, woof, or bow-wow in English, but other languages have other interpretations of the sound that dogs make, including waouh (in French), guau (Spanish), voff (Icelandic), wan (Japanese), and blaf (Dutch).
Loud appliances like a vacuum cleaner, blender, lawnmower, or even a loud television can be very stressful for a dog. Dogs that are sensitive to noise to begin with might start to panic at even the slightest increase in general noise around the house.