The Coughing Pet

Cough is a common problem in dogs but occurs less frequently in cats.  Cough is caused by irritation of the throat, airways, or the lungs.  The main airway to the lungs, known as the windpipe or trachea, branches into smaller airways called bronchi, which branch several more times as they travel to the deeper parts of the lung.

There are many causes of cough.  A thorough history and physical examination help me decide which causes of cough are most likely in your pet and helps me decide which diagnostic tests to recommend and which therapies are most likely to be effective.  Cough originating from the trachea may be stimulated by lightly squeezing the trachea.  Cough due to heart disease may be accompanied by a murmur or abnormal heart rate or rhythm.

Your description of the nature of the cough, when the cough occurs, and if anything brings on coughing can be very helpful in pinpointing the cause of coughing in your pet.  Some causes of cough result in difficulty breathing between coughing episodes whereas with other diseases, the pet breathes normally between coughing episodes.  Some types of cough occur more commonly at night when the pet is trying to rest.  Animals with heart failure, collapsing trachea and lung edema cough more at night than during the day.

Cough caused by tracheal irritation or tracheal collapse often occurs when the pet is excited or is tugging on its collar.  Cough due to tracheal collapse may be stimulated by drinking water.  Coughing that occurs during or shortly after eating may be due to disease of the larynx or esophagus.  Some coughs sound moist and others are harsh and dry.  Moist coughs indicate the accumulation of fluid (water, blood, or pus) in the airways or lungs.

Animals that have exposure to other animals in a shelter or boarding facility are more likely to have an infectious cause for coughing.  The region of the country in which you live or to which you and your pet have traveled, influences the likelihood of some diseases like heartworm disease and fungal infections of the lung.  Heartworm disease occurs in both dogs and cats and is most common in parts of the country that have lots of mosquitoes.

The age and breed of the pet also influences what causes of cough are most likely.  Young animals are more likely to develop a cough due to infections with bacteria or viruses.  Young to middle aged cats may develop wheezing and cough due to asthma.  Cats with asthma have sudden episodes of wheezing and coughing but are normal in between episodes.  Middle-aged to older, small breed dogs are more likely to have heart disease due to leaky valves.  Middle-aged to older, large breed dogs are more likely to develop paralysis of the larynx.

Tracheal collapse occurs most commonly in middle to aged overweight small breed dogs.  Tracheal collapse is rare in cats.  The cough is often described as sounding like a goose honking.  Treatment for tracheal collapse includes weight reduction and intermittent use of cough suppressants and sedatives.  Surgery can be performed in dogs with severe collapse that don't respond to weight reduction and cough suppressants but often surgery is not effective.

Kennel cough or infectious tracheobronchitis is caused by several infectious organisms, including bacteria and viruses.  Vaccinations are not 100% protective against the agents of kennel cough.  Coughing due to kennel cough usually becomes apparent within a few weeks of exposure of your dog to other dogs in a kennel or show environment.  Kennel cough usually resolves itself without any treatment.  If the cough is severe enough that the pet has difficulty sleeping or people in the house have difficulty sleeping, cough suppressants can be given to suppress the frequency of cough, allowing the pet and human members of the household to get rest while the disease runs its course.  If the cough does not subside in a week to ten days, your pet should be evaluated for other diseases of the lungs or airways.

Cough can be caused by heart disease, which is diagnosed by a chest x-ray, an electrocardiogram which measures the electrical activity of the heart, and often by a heart ultrasound which allows the veterinarian to view the inside of the heart, including the valves and the thickness of the walls of the heart muscle.  Heart disease may cause heart enlargement that puts pressure on the airways causing cough or the heart may fail and lead to edema of the lungs.  Allergies to particles in the air including dust, pollens, and smoke can cause allergic lung disease and coughing.

Treatment of coughing patients depends upon the disease diagnosed and may include cough suppressants, antibiotics for bacterial infections, and steroids for allergic lung disease.  Avoid self-medicating your pet as the treatment for one cause of cough may be very wrong for the treatment of another type of cough.

Dr. Lamb is the Veteranarian at the Manchester Animal Hospital.