Drowning, while rare, is often fatal and a critical situation that veterinary professionals are likely to encounter. Although detailed evidence on animal drowning is limited, much of our understanding is drawn from human medical literature. This article outlines essential knowledge and protocols for managing drowning in pets, ensuring veterinary teams are prepared for such emergencies.
Causes and Pathophysiology of Drowning in Animals
Drowning in animals can result from various incidents such as swimming accidents, falling into water, seizures, falling through ice, or even animal abuse. The term "drowning" applies to all cases regardless of the outcome, eliminating the need for terms like "near-drowning" or "non-fatal drowning." If a pet presents collapsed or struggling to breathe after being in water, drowning should be a primary consideration.Pathophysiology: Drowning involves immersion (liquid splashing on the face) or submersion (airways submerged below the surface) leading to respiratory impairment. This results in the aspiration of liquid, airway flooding, hypoxemia, brain hypoxia, apnea, and potentially death. This can happen within minutes, though hypothermia can delay the process due to its neuroprotective effects.
Secondary Drowning
Secondary drowning occurs when aspirated water disrupts lung surfactant, causing alveolar collapse and ventilation-perfusion mismatch. Damage to alveolar pneumocytes and pulmonary vasculature leads to an inflammatory response and protein-rich fluid leakage into the lungs, resulting in non-cardiogenic pulmonary edema (NCPO). This can develop hours to days after the incident. Laryngeal spasm can also cause negative pressure pulmonary edema (NPPO), potentially leading to secondary drowning with minimal water aspiration.
First Aid for Drowning Pets
At the site of drowning, immediate efforts should focus on reviving the pet. Although draining pulmonary fluid by tipping the patient head-down may be attempted, it is often ineffective. The Heimlich maneuver should be avoided due to the risk of causing further fluid aspiration. Instead, mouth-to-nose rescue breaths can be beneficial for apneic patients, and cardiac compressions are vital for those in cardiac arrest. Resuscitation should continue en route to the veterinary clinic.
Preparing the Veterinary Team
Before patient arrival, the veterinary team should prepare by setting up oxygen therapy, crash carts, endotracheal tubes, laryngoscopes, intravenous access, and necessary imaging and monitoring equipment. Given the high risk of respiratory failure in drowning patients, preparation is crucial.Ongoing training through emergency and critical care (ECC) CPD courses and crash drills can improve team confidence and efficiency. Training in focused assessment with sonography in trauma (FAST) is also valuable for evaluating drowning patients.
Stabilizing the Patient
Oxygen Therapy: Immediate oxygen therapy is essential. Temporary measures include masked oxygen until the patient can be moved to an oxygen kennel or fitted with nasal prongs/catheters. Minimizing patient stress is key in method selection.Intravenous Access and Monitoring: Obtain IV access and SPO2 readings promptly. Anxiolytic sedation with butorphanol may be necessary for a full clinical assessment.Advanced Respiratory Support: Continuous positive airway pressure (CPAP) oxygen may be needed if supplemental oxygen is insufficient. In severe cases, mechanical ventilation under anesthesia might be required.Cardiac Arrest: Follow current RECOVER guidelines for cardiopulmonary resuscitation and adrenaline administration if cardiac arrest occurs.
Investigations and Treatment
A comprehensive clinical examination and baseline blood tests are critical to identify any underlying conditions that could predispose the pet to drowning. Blood changes like stress leukogram or hyperglycemia, electrolyte disturbances, and signs of hypoxemia and hypotension must be monitored. Drowning patients are also at risk of hemostatic disorders, including disseminated intravascular coagulopathy.Lung Ultrasound: 'B lines' indicating interstitial-alveolar edema can be detected via ultrasound and are a practical alternative to thoracic radiography, especially for monitoring intensive care patients.Radiography: Mixed bronchial and interstitial lung patterns might be seen, but restraint for radiography may increase risk in dyspneic patients.Oxygen Therapy and Supportive Treatment: Oxygen therapy is fundamental, along with managing hypothermia and shock. Judicious use of IV fluids (lactated ringers solution) is recommended for hypovolemia and organ perfusion.Antibiotics and Other Treatments: Prophylactic antibiotics are controversial and should be administered based on signs of pneumonia and culture sensitivity results. Bronchodilators may be beneficial, but there is limited evidence for the use of diuretics or glucocorticoids in drowning cases.
Monitoring and Prognosis
Monitor for signs of bacterial pneumonia and general health indicators such as oxygen saturation, creatinine, urea, glucose, electrolytes, and urine output. Prognosis varies, with one study showing a survival rate of 18 out of 25 dogs, while 0 out of 3 cats survived. Key factors influencing outcomes include the duration of submersion, severity of metabolic acidosis, and promptness of resuscitation.
Conclusion
Effective management of drowning cases requires preparation, training, and a coordinated team effort. Advanced ECC training can significantly enhance the team's ability to provide rapid and effective treatment, improving the chances of survival for drowning patients.
