Panting is seen in both dogs and cats, but is more common in dogs. Panting is often seen associated with environmental changes such as anxiety, fear, excitement, exercise and heat. However, panting may reflect disease, and should not be ignored or assumed "normal" unless there are circumstances around the panting that suggest it is acceptable for the situation at hand. If your pet is panting excessively, or more often than normal, it is important to be evaluated by a veterinarian.
There are many causes of panting. Because panting may be a normal response to environmental and psychological events, it is quite feasible that no underlying illness exists and a full diagnostic workup is not in order. If, however, panting is excessive or your pet is in distress, it is important to identify an underlying cause.
Respiratory Disorders Upper respiratory tract disorders may limit the ability to breathe normally. These include nasal blockages, laryngeal dysfunction (disorders of the voice box), nasopharyngeal polyps (benign growths of the nose and pharynx) and collapsing trachea (rare).
Lower respiratory tract disorders may not allow for ample gas exchange at the level of the lung, causing panting. Some examples include pulmonary edema (fluid in the lungs), hemorrhage or cancer, lung lobe torsion (twisting), emphysema and asthma.
Diseases of the chest cavity may not allow the lungs to expand. Examples include pneumothorax, (air in the chest), pleural effusion (fluid in the chest cavity), mediastinal masses (growths in the chest), and diaphragmatic hernias (the displacement of abdominal contents into the chest cavity).
Cardiovascular Disorders Pulmonary (lung) disorders include vascular disease such as heartworm disease and pulmonary thromboembolism, which is blockage of a vessel by material carried through the blood stream.
Cardiac disorders include heart failure, cardiomyopathy (heart muscle disease) and congenital heart abnormalities.