Abstract

There are numerous factors that impact the pulmonary health of cetaceans. These may include age, immune status, concurrent illness, neoplasia, inhalation of debris, bacteria, or fungi, hematogenous spread of disease, exposure to irritating or caustic agents, etc. Cetaceans may be more prone to some forms of respiratory disease as a result of their unique anatomy. Many terrestrial species appear to depend on variations in the nasal pharynx such as the conchae and turbinates to help trap inhaled debris before it enters the larynx. The efficiency of the upper respiratory system, even in terrestrials can be overloaded or compromised by numerous factors such as excessive numbers of pathogenic organisms or a compromised immune system.

Air flowing through the upper respiratory system in cetaceans encounters little anatomic resistance before entering the glottis. From the glottis inhaled air must make an almost 90 degree turn before entering the trachea. The floor of the larynx, when expanded on exhalation then inspiration, exposes numerous folds and recesses that may be capable of trapping larger particles carried by the normally high velocity airflow. Smaller particles may remain suspended in the air column and gain access to the lower respiratory system. The potential air velocity may be compromised by decreased activity or resting behavior in cetaceans. This may also result in increased exposure to debris, bacteria or fungi.

Symptoms of respiratory disease include dyspnea, tachypnea, respiratory noise, exercise intolerance, inappetence, depression, and behavioral changes. Diagnosis of pulmonary disease can be aided by numerous methods that include physical exam with signs of respiratory compromise, auscultation, bloodwork, respiratory cultures, radiographic examination, computerized radiographs, thoracic ultrasound, blood gases, and pulmonary endoscopy.

Some infectious agents such as Pseudomonas aeruginosa and many fungi may result in pathology primarily involving the trachea, bronchi, lungs, pleura and associated lymph nodes.

Other pathogens such as Zygomycetes fungi and Nocardia may be spread by the vascular system localizing in many different tissues including the brain, joints or skin. The pulmonary relationship to these sites may be difficult to determine initially and these organisms are often very resistant to therapy.

Treatment approaches are similar to other species. There may be numerous complicating factors including unknown etiology, unknown portal of entry, location of the primary site, resistance to therapy, diagnostic difficulty, rapid onset of signs, and in some cases rapid death. Pulmonary infections with fungi may linger for extended periods resulting in large lesions that appear resistant to therapeutic approaches. Pulmonary conditions involving inhalation of non-infectious debris may result in chronic pulmonary symptoms since antibiotic agents may not be effective.

Prevention may play the biggest role in pulmonary disease in cetaceans. Recognizing the potential ease of access to the cetacean respiratory system, personnel must do all that is possible to decease exposure to any dust, aerosol, or poor air quality. Some cleaning techniques around exhibits, while increasing efficiency, may result in decreased air quality. In an outdoor environment this will include the elimination of exposure to pressure washing that aerosolizes dirt and debris, blow packs that redistribute dirt and leaves, mechanized brushes, dirt left behind on road surfaces that could be blown by the wind, construction and excavation activity, dirt mounds exposed to the wind, and air conditioner systems. Exhaust from combustion engines should also be avoided. Sprinkler systems that form spray or mist may aerosolize infectious agents as well as contaminants. Watering systems should be of a non-spray variety. Indoor environments must be monitored for air contaminants such as fungi and bacteria. Properly sized filters should be used in air circulation systems, to more efficiently trap contaminants, and changed routinely. Air exchange rates should be adequate to avoid the air becoming stale or heavy with chemical odors. Pressure washing should not be used indoors near cetaceans.

Chemical exposure should also be closely monitored. Cleaning solutions such as chlorine products may result in a range of effects from pulmonary irritation to fatality and should be avoided near the animals. Inexperienced animal personnel should be educated to the potential hazards of chemicals such as disinfects when joining the staff. Other departments such as horticulture or park personnel who are responsible for cleaning should also be educated to the potential respiratory problems the animals face so there is more cooperation in their long-term health care.