Yes, dogs can suffer from anxiety. My German Shepherd Nyla has had anxiety since day one. When we got her, she was not socialized with other pets or humans prior, which can develop problems later on. It is important for dogs to have that socialization within their first few weeks of life.
Signs of Anxiety
Nervousness, shaking, and hiding their tail is a big sign. Also when they lock or bite themselves excessively.
Nyla barks and howls uncontrollably, all day due to her anxiety. She also has excessive energy and panting.
Again, poor socialization is a big part. Being abandoned, neglected, and mistreated is a cause of anxiety in dogs.
Sickness, pain, and past negative experiences cause anxiety as well. Many rescue and shelter dogs suffer from this because of it.
How to Help
Occupy your dog with toys and treats while you are away. Leaving for a some period of time and slowly increasing it will help if they have separation anxiety.
Staying calm during the whole process is a big factor. Dogs feed off of your energy and can sense it. If you are worried and anxious, so will they.
Exercise daily! You can reduce anxious behaviors by exercising your pet.
Opt into a dog daycare. If you work during the day, maybe having your dog be with other pets and humans will reduce their anxiety! They will be fed, groomed and exercised for the time period.
Lastly, you can talk to your vet about any medications that will improve their mood. Anxiety could also be caused by an underlying health issue, please talk to a veterinarian before giving your dog any medication.