Unlike exposure to other toxins, many Agent Orange symptoms tend to take several years to decades to present, and can cause a host of health issues. Initial symptoms tend to include common side effects found with many other illnesses, as well as neurological and psychological problems.
Heavy breathing or panting. Most dogs will pant from time to time because they are stressed or excited, but when dogs pant for no apparent reason and the panting becomes excessive, this can definitely be a sign that a dog is experiencing pain.
Illness. A scarier side of panting and drooling symptoms is a serious illness, such as heart failure, respiratory distress and cancer. Dogs pant and salivate when they are having trouble swallowing and breathing, which can be a sign of pneumonia or congestive heart failure.