Signs of Anxiety include:
Licking lips when no food is nearby.
Panting when not hot or thirsty
Yawning when not tired
Hyper vigilance - looking in many directions
Pacing
Trembling
Hyper salivation
Hiding
Frequent barking or whining
Some animals may be predisposed to developing anxiety due to their genetics. Other animals become fearful or anxious because of experiences during early development. Learning experiences throughout life can also contribute. Triggers for a pet's anxiety can be "social" referring to interactions with other people or animals, or "environmental" such as noises, sights, smells and general living conditions.
You must keep the context of the behaviors in mind when trying to determine the cause of them. A dog that yawns right before bedtime is likely doing so because he is tired, while a dog that yawns while wide awake - for example, an animal in the hospital for a routine examination - is most likely fearful or anxious.
The appropriate response to these behaviors is going to be dependent on the context in which the behavior occurs. One thing is clear, though - never respond to anxious behaviors with corrections, such as verbal or physical punishments. Punishing the pet will only exacerbate his or her anxiety. The first step in determining treatment options is an evaluation by an expert consultant that includes a detailed history to identify factors that contribute to the anxiety. This should include assessment of the dogs's management, home environment, daily routine, social dynamics in the household and specific examples of anxious behaviors.
Details that a behavioral consultant will want to know include who was involved, where and when the behavior occurred, what the dog did, how the owners responded to the behavior and how the incident resolved. Treatment strategies commonly include a combination of management to avoid anxiety-provoking situations, behavior modification to alter the dog's association and response to triggering stimuli, and potentially anti-anxiety medications to reduce the intensity of the anxious response.
Some pet care professionals and pet owners ask whether crating an anxious pet is an appropriate response. Again, the answer depends on the context in which the anxiety occurs as well as the dog's history with crate training. For dogs with separation anxiety or noise phobias, crating is not recommended if the dog has not previously been trained to accept confinement or has a history of trying to escape the crate. Many dogs hurt themselves during escape attempts, and crate confinement can escalate their anxiety and panic. In other cases, dogs may actively seek out their crate as a "safe place" when feeling anxious or fearful. This is why a thorough history is so important in coming up with an appropriate treatment plan.
From Pet Sitter's World, May/June 2014.