Coughing in dogs can have many different causes. In most cases, determining the cause is essential to being able to effectively treat the cough. Measuring the sleeping respiratory rate of a dog whose primary symptom is coughing can be a useful tool in determining the cause of the cough.
Congestive Heart Failure and Coughing in Dogs and Cats
Heart disease is, unfortunately, a common disease problem in dogs. There are many forms of heart disease, ranging from defects of the valves within the heart to disease within the heart muscle itself. However, whatever the cause of the heart disease, congestive heart failure is often the end result.
Congestive heart failure occurs when pressure builds up inside of the heart and, if the right side of the heart is predominantly involved, this increased pressure within the heart chambers leads to increased pressure within the blood vessels as well, causing them to become leaky. As fluid leaks out of the blood vessels, it enters the lungs, creating what is known as pulmonary edema (an excessive amount of fluid accumulation within the lungs).
As the lungs fill up with fluid, a cough results. Other symptoms associated with congestive heart failure include a bloated, fluid-filled abdomen, an abnormal respiratory rate, difficulty breathing, restlessness, lack of appetite and syncope (fainting).
It is important to remember that dogs can suffer from heart disease without being symptomatic and without experiencing congestive heart failure. Congestive heart failure is a progression of heart disease.
Coughing in the Canine Caused by Respiratory Disease
Another extremely common cause of coughing in dogs is respiratory disease. There are many forms of respiratory disease and potential causes include:
- viral infections
- bacterial infections
- fungal disease
- parasites
- inflammatory reactions
- allergic reactions
- bronchial disease
- tracheal collapse
- emboli (clots)
- irritants, such as cigarette smoke
Symptoms seen with respiratory disease in dogs often appear very similar to the symptoms seen with congestive heart failure.
Heart and Respiratory Disease in the Same Dog
To make matters even more complicated, it is not unusual for dogs, particularly elderly dogs, to suffer from both respiratory and heart disease at the same time. When this occurs, it can be extremely difficult to determine whether the cough is resulting from the respiratory component of the dog's disease or the cardiac component. Obviously, treating a dog for heart disease when the cough is resulting from respiratory disease is not likely to be very effective. The reverse is true as well.
Sleeping Respiratory Rate to Differentiate Between Congestive Heart Failure and Canine Respiratory Disease
While a sleeping respiratory rate may not provide a diagnosis by itself, when combined with additional diagnostics such as radiographs and/or echocardiography, the sleeping respiratory rate can provide a valuable clue as to whether a cough is a result of respiratory disease or congestive heart failure.
The sleeping respiratory rate is measured by counting the number of breaths that the dog takes in the course of one minute. Normal sleeping respiratory rates should be less than 30 and often less than 25 is perfectly normal. The sleeping respiratory rate should be measured while the dog is sleeping soundly in his own environment (i.e. his own home).
Dogs with normal sleeping respiratory rates are unlikely to be suffering from congestive heart failure. An elevated sleeping respiratory rate can be due to either congestive heart failure or respiratory disease and dogs that are experiencing rates greater than 30 breaths per minute should be examined by their veterinarian to determine the cause. However, for a dog that is coughing, a sleeping respiratory rate less than 30 breaths per minute indicates that congestive heart failure is not likely to be the cause of the cough, even if heart disease is present.
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