E708
Respiratory Problems

Introduction: The respiratory tract or system is the collective set of parts and tissues which provides for the inhalation of air, the passage of oxygen into the bloodstream, the passage of waste gases out of the bloodstream, and the exhalation of those same waste gases into the environment. This section concentrates on abnormalities in the parts and tissues of the lungs, trachea, larynx, and mouth. Some problems may actually originate outside of the respiratory tract, but have a direct influence on these structures and the normal passage of air and exchange of oxygen.

Causative Agents: There are many reasons for an animal to have respiratory problems. The following list covers only a few of the most common:

1. Infectious

- Bacteria
- Viruses
- Fungi
- Parasites, including heartworm disease

2. Trauma

- Bleeding/Hemorrhage
- Fractured ribs
- Diaphragm injuries
- Scar tissue formation
- Air leakage into the chest space (pneumothorax)

3. Heart disease

4. Drugs or noxious substances

- Rodenticide poisons
- Smoke inhalation
- Aspiration pneumonia (inhaling vomit or food into the lungs)
- Drowning/Near drowning

5. Allergies

6. Cancer

7. Electric shock (i.e. chewing on electrical cords)

8. Congenital birth defects

- Brachycephalic airway syndrome

9. Degenerative diseases

- Collapsing trachea

10. Pulmonary thromboembolism (blood clots lodged in the lung vessels)

Clinical Signs: Depending on the cause of the respiratory problem, many different signs are possible. In general, coughing, difficulty breathing, or shortness of breath are universal clinical signs, and may occur with any of the above causes.

  1. Coughing is an extremely important diagnostic clue. Careful attention should be given to the nature of the cough (dry or moist), presence of any discharge which may be expelled with a cough, and to the circumstances surrounding the cough (i.e. time of day, worsening with exercise, eating or drinking). Determining what kind of cough is present may be the most helpful evidence in guiding a veterinarian toward the next diagnostic steps to take. See page E122 for additional information on coughing.
  2. Shortness of breath will occur with any cause of respiratory illness if the illness is severe enough. Whether the shortness of breath or difficulty breathing occurs when the dog inhales or exhales, whether the dog stands or sleeps in different positions to aid the breathing, and whether the breathing is more rapid than usual are all important pieces of information in the quest for a specific diagnosis.
  3. Fever commonly occurs with many of the infectious and cancerous causes of respiratory problems. Another important point to note when considering the temperature of a dog is the fact that panting is the primary method of eliminating excess heat (dogs sweat only on their footpads). Any illness which may decrease the flow of air into or out of the mouth, or between the mouth and the lungs, may potentially lead to hyperthermia (increased temperature).
  4. Weakness will occur if insufficient oxygen exchange is taking place. Because both muscle tissue and brain are oxygen-deprived in such situations, the weakness usually involves the entire body and may be associated with decreased consciousness. See page E948 for more information on weakness.
  5. Color of the mucous membranes is an important factor regarding the function of the lungs. If inadequate oxygen exchange takes place, the mucous membranes may be a purplish/blue color. The medical term for this condition is cyanosis and it is common with certain diseases of the heart and other severe respiratory problems. Pale mucous membranes may also help determine the diagnosis, because they may indicate shock or bleeding/hemorrhage problems. See page B105 for additional help.
  6. Loss of consciousness, collapse, coma, and death may also occur in severe cases. The body depends on the respiratory system on a minute by minute basis; with severe damage and compromise to this system, it will not be able to sustain life. See E200 for additional help.

Diagnosis: A complete and thorough history is important for an accurate diagnosis. This requires that the owner be prepared to give specific information concerning the pet. Some essential pieces of information may include the following:

  1. The age, breed, and sex of the animal
  2. Vaccination and heartworm prevention status
  3. Travel history
  4. Past medical history
  5. Any other animals or people from the same household experiencing the same problem
  6. Home environment
  7. Details about the current problem
  8. Duration of the current problem
  9. Progression of disease
  10. Any other problems noted, even though they may not seem significant
  11. Any recent treatments or medications

Once the history is taken, a physical exam is performed. A complete examination of the respiratory system includes listening to the lungs and trachea with a stethoscope, temperature measurement, and examination of the mouth/throat region, eyes, lymph nodes, and mucous membranes. Additional procedures that may be required include radiography (X-rays) of the upper body, evaluation of a fluid sample from the lungs (the sample is usually obtained by means of a test known as a transtracheal wash or aspiration), and/or examination of the airways using an endoscope. These procedures help the veterinarian to more specifically diagnose the problem. For additional information on the above procedures and tests, refer to Sections B and D.

Treatment: Depending on the particular cause of the present problem, a combination of many different treatments is available. Some general treatments/supportive care for patients with respiratory disease include antibiotics, anti-inflammatory medications, oxygen, cough suppressants, and IV fluids.

More specific treatment varies as widely as does the list of respiratory problems. Other therapeutic procedures include thoracocentesis (insertion of a needle or tube into the chest space to draw out fluid or air), tracheostomy (opening a hole into the trachea to help the animal breathe while an obstruction in the mouth or larynx is removed), chest percussion (gentle drumming on the chest wall with a cupped hand to help dislodge and move debris into the airways), humidification therapy (to help moisten lodged debris in the lungs and aid in oxygen transfer), and surgery.

Prevention: Many problems with respiratory infections can be avoided with routine vaccinations and de-worming. Careful attention to avoid exposure to diseased animals is also critical. A quick recognition and then proper treatment is the best approach. Quick recognition of a problem by the owner relies greatly on a basic knowledge of a pet’s normal behavior. For suggestions on normal respiratory rates and how to listen to the lungs, refer to pages A560 and B890.  The information found on page A30 can be helpful in learning how to be an observant and alert pet owner. Vaccination and de-worming suggestions can be found on pages A905 and A622.