It is common for people to refer to their dog disease symptoms when describing what they observe with respect to how their dog is doing in relation to a matter of concern.  however, it is less correct to say that a dog is experiencing certain symptoms of a disease.  instead, the more correct means of describing what a dog an owner is observing in relation to illness in their dog is to say that he/she observes certain signs of disease. 

A symptom is defined as a departure from normal function or feeling, indicating the presence of disease or abnormality, which is noticed by the patient.  a symptom is subjective, observed by the patient, and not measured.  It is typically related to an illness and not a normal state of feeling.  Although there is little doubt that dogs experience signs of illness (dog disease symptoms), since dogs cannot readily express verbally what they are experiencing, it is difficult for owners to completely understand what dog disease symptoms they are experiencing.

The best example of this is when pain is a feature of disease.  Pain is something that can be only be felt by the individual experiencing it and would be considered common dog disease symptoms.  however, people who observe that a dog is in pain are not actually experiencing it, but observe signs of pain such as vocalization or lameness that are signs that the dog may be in pain. 

The correct way to describe what a person observes in relation to departure from normal function is to characterize it not as dog disease symptoms, but dog disease signs.   a sign is defined as a feature of disease that is noticed by other people.  Since people are the individuals observing and describing what is wrong or right with their dog, what they are witnessing are signs of disease.  Features of disease such as results of laboratory tests can only be measured and not experienced by individuals and are always considered to be signs of disease. 

To sum up, a symptom can be defined simply as a feature of disease noticed by the patient.  a sign is noticed by other individuals.  It is not the nature of the sign or symptom which defines it, but who observes it.  Since people are observing what is happening to their dog, they are by definition observing dog disease signs, not dog disease symptoms.