Dogs like people can get anxious for may different reasons. Some of the common triggers include:
gus_red

Thunder and Storms
Separation
Loud noises
Handling especially ears and paws
New places and people
Men and Children.

Susannah did this painting of our dog Gus on the first day he left the pound. Unfortunately, he had a poor puppy hood which manifested in him becoming a very anxious adult dog.

Anxiety can be played out in forms of behaviour and physical symptoms like Obsessive scratching, barking, hiding, panting and more.
It is very important to try and address these issues before they become a problem.

Vets, animal behaviourists and trainers can all assist you with these problems or direct you to the right people.

Disclaimer: The tips here are general advice only and if you are at all concerned about the problem please seek professional advice straight away.