Bottlenose Dolphin Pneumonia
Pneumonia is an inflammation of the lungs, usually caused by infection. In bottlenose dolphins, it is one of the most common respiratory diseases and a leading cause of death, particularly in stranded or weakened animals. This disease affe...
What is it?
Pneumonia is an inflammation of the lungs, usually caused by infection. In bottlenose dolphins, it is one of the most common respiratory diseases and a leading cause of death, particularly in stranded or weakened animals.
This disease affects a marine mammal whose breathing depends entirely on the lungs; any significant lung damage can quickly become life-threatening, because the animal must be able to surface regularly to breathe.
Key point
Pneumonia is one of the leading causes of mortality in bottlenose dolphins, particularly following stranding; prompt care by a specialized team is essential.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Signs suggesting pneumonia in bottlenose dolphins include abnormal breathing at the blowhole: noisy, irregular breathing, or breathing that is faster or shallower than normal. The animal may swim abnormally, remain motionless at the surface for long periods, or conversely have difficulty staying at the surface.
Progressive weight loss is often seen, along with isolation from the group, reduced activity, and unusual behavior. Some animals show fever (detectable only by veterinary examination) and declining general condition.
In advanced cases, frank respiratory distress can develop, with the animal severely weakened and sometimes unable to maintain its position at the surface on its own to breathe.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Bottlenose dolphin pneumonia is most often infectious in origin. Bacteria (including opportunistic marine or terrestrial germs such as certain species of Brucella, Streptococcus, Escherichia coli, or mycobacteria) can colonize the lungs, particularly in weakened animals.
Fungi can also be responsible, especially in chronic infections or immunocompromised animals.
Lung parasites (roundworms lodged in the respiratory tract or sinuses) are a common and sometimes severe cause in cetaceans, promoting secondary bacterial infections.
Viruses (such as cetacean morbillivirus) can also weaken the animal and create conditions for secondary pneumonia.
Lastly, aspiration of water, sand, or gastric contents (aspiration pneumonia), sometimes seen after stranding or respiratory distress, can cause severe lung inflammation.
Young, elderly, weakened or immunocompromised animals are more vulnerable. Stress from stranding, injury, exposure to environmental pollutants (heavy metals, organic pollutants) or a pre-existing viral infection (morbillivirus) increase susceptibility to pneumonia.
Heavy lung parasitism, malnutrition or deep wounds that may lead to contamination are also recognized risk factors in wild cetaceans.
Transmission
Transmission depends on the causative agent. Some bacteria and parasites can spread between individuals through close contact, contaminated water, or ingestion of prey infested with lung worm larvae. Viruses such as cetacean morbillivirus can spread between dolphins through close social contact, particularly during disease outbreaks.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Diagnosis is difficult in a marine animal and relies on several combined sources of information. During stranding or care at a rehabilitation centre, the veterinarian observes swimming behaviour, breathing frequency and sound at the blowhole, and the animal's general condition.
Thoracic auscultation is possible but limited by the thickness of blubber and the aquatic environment. Blood samples may reveal inflammation or infection. Sampling at the blowhole (expired breath) or bronchoalveolar lavage sometimes allows identification of the causative organism.
Imaging (chest radiography or ultrasound) and sometimes CT scanning, when the animal is stabilized and transportable, help visualize the extent of lung lesions. In dead animals, necropsy remains often the only way to obtain a definitive diagnosis, particularly in stranding studies.
Treatment
Treatment is only possible in a specialized rehabilitation centre for marine mammals, never independently. It relies, depending on the identified cause, on antibiotics, antifungals or specific antiparasitics combined with supportive care (rehydration, nutritional support, pain and inflammation management).
Oxygen therapy or respiratory support may be considered in equipped facilities. Close veterinary monitoring is essential to adapt treatment to the animal's progress.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
There is no specific prevention applicable to wild populations. In a rehabilitation centre or under human supervision, prevention involves good health monitoring, good water quality, parasite control, stress management and early detection of any abnormal respiratory signs.
Preserving the quality of the marine environment (limiting pollution, discharge and disturbance) indirectly helps reduce the factors that weaken dolphins and make them more vulnerable to respiratory infections.
Possible complications
Untreated or poorly controlled pneumonia may progress to a lung abscess, septicaemia (generalized infection), severe respiratory failure or death.
In dolphins, respiratory disease is one of the leading causes of mortality observed during strandings, particularly in cases of prior weakening (parasitism, stress, pollution, injury).
When to see a veterinarian
Any stranded dolphin or dolphin in distress must be reported immediately to the authorities or specialized stranding networks — never handled alone.
Observation of abnormal, noisy, or very frequent breathing at the blowhole.
Visible weight loss or abnormal swimming in a captive animal or one in a care facility.
Marked lethargy, isolation, or loss of appetite in a dolphin under human supervision.
Onset of fever or general signs of illness in an animal already being monitored by a veterinary team.
Transmission to humans
Some agents responsible for pneumonia in cetaceans, particularly certain bacteria of the genus Brucella, are potentially transmissible to humans through close contact with a sick or dead animal (handling, necropsy). Protective measures (gloves, mask) are recommended for exposed personnel.
Prognosis
The prognosis is variable and depends on the cause, the severity of lung lesions, and how quickly treatment is started. In a stranded wild dolphin, the prognosis is often guarded to poor, as pneumonia is frequently discovered at an advanced stage.
In a care facility, with early diagnosis and appropriate treatment, some animals may recover, but the outcome remains uncertain, particularly if an underlying disease is present (severe parasitism, virus, immunosuppression).
Frequently asked questions
Can dolphin pneumonia be transmitted to humans?
Some causative agents, such as certain bacteria (Brucella) found in cetaceans, are potentially zoonotic. The risk remains low but justifies precautions (gloves, protective equipment) when handling sick or dead animals, particularly for personnel at rehabilitation centers.
How do you know if a wild dolphin has pneumonia?
In nature, it is difficult to observe directly. Indirect signs include abnormal swimming, noisy or irregular breathing at the blowhole, weight loss, and isolation from the group. Definitive diagnosis often requires specialized centre care or necropsy.
Can a stranded dolphin with pneumonia be saved?
This depends on how early treatment is initiated, the severity of the lesions, and the causative agent. Some animals respond well to treatment in a specialized centre, others do not, particularly if the pneumonia is very advanced or associated with other diseases.
Are lung parasites common in dolphins?
Yes, pulmonary worms are a classic cause of respiratory disease in wild cetaceans and can promote secondary bacterial infections responsible for pneumonia.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
CDC — Centers for Disease Control and Prevention
Content reviewed by the TunisieVet editorial team · Updated 31 August 2026
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