Hypoxemia Due to Aspiration of Water in Dogs

 

Near-drowning is determined by an event that involves prolonged submersion in water, followed by survival for at least 24 hours afterward. Following submersion, typical symptoms include elevated carbon dioxide levels in the bloodstream, stimulated respiration, and subsequent aspiration of water into the lungs. In rare cases, hyperventilation prior to submersion, or laryngospasm (spasmodic closing of the larynx) may prevent aspiration of water, an involuntary reaction that can lead to a condition called dry drowning.

 

There are four phases in a typical drowning: breath-holding and swimming motion; water aspiration, choking, and struggling for air; vomiting; and cessation of movement followed by death. The mammalian diving reflex may occur, leading to a slowed heart rate, a halt in breathing, and blood circulation limited only to the essential organs of the body. Large volumes of water are not typically aspirated at this stage.

 

Fresh water aspiration leads to a collapse of respiratory cells with possible infectious pneumonia. Hypertonic seawater aspiration leads to a diffusion of water entering the lungs and into the alveoli (the air cells of the lungs). Since the dog cannot obtain enough oxygen, oxygen levels in the blood drop and the blood becomes acidotic (abnormal increase in acidity).

 

Submersion time, temperature of the water, and the type of water the dog is submerged in (whether the water is fresh, salt, or chemical) will significantly affect the development of organ damage.

 

Symptoms and Types

 

• Bluish skin and gums
• Coughing with clear to frothy red sputum (spit-up)
• Cessation of breathing
• Difficulty breathing
• Crackling sound from the chest
• Vomiting
• Semi-conscious and dazed to comatose
• Increased or decreased heart rate
• The heart may cease to beat

 

Causes

 

• Owner negligence
• Inadequate safety precautions
• Young, inexperienced dog (less than four months of age)
• Dog was in or near water at the time of a seizure
• Following head trauma
• Rapid drop in blood sugar, abnormal heart beat rhythm, or fainting episode while in body of water place dogs at higher risk of drowning

 

 

Diagnosis

 

Your veterinarian will perform a complete physical exam on your dog. Standard laboratory tests will include a blood chemical profile, a complete blood count, a urinalysis and an electrolyte panel.

 

Chest X-rays may show aspiration pneumonia or fluid in the lungs one to two days after the near-drowning. Foreign body inhalation may produce segmental lung collapse. Pulmonary injury progressing to acute respiratory distress syndrome (ARDS) is possible.

 

An endotracheal or transtracheal wash, followed by a cytologic evaluation and culture with sensitivities is indicated. Electrocardiographic monitoring to examine the electrical currents in the heart muscles may be performed to assess heart damage. Your veterinarian will also want to determine the auditory evoked response (BAER) for hearing loss assessment. Cervical X-rays, computed tomography (CT), or magnetic resonance imaging (MRI) of the brain and brain stem may be helpful in select cases.

 

Treatment

 

Clear any airway obstructions and give mouth-to-muzzle resuscitation on the site of the accident. Professional medical treatment will need to follow immediately. Your dog will need to be treated on an emergency inpatient basis, with oxygen supplementation given at the hospital. If your dog has severe hypoxemia, hypercapnia, or imminent respiratory fatigue, a ventilator may be required for respiratory assistance.

 

Gravitational drainage or abdominal thrusts (i.e., the Heimlich maneuver) are not recommended in the absence of an airway obstruction owing to the high risk of regurgitation and subsequent aspiration of stomach contents. Fluid therapy and acid-base/electrolyte management are crucial for bringing the fluid balance back to normal levels. If your dog is hypothermic, your veterinarian will gradually rewarm the dog's body with blankets over two to three hours. Prolonged parenteral (intravenous) nutrition may be required for your dog if it is suffering from severe brain or lung injury.

 

Living and Management

 

Generally, dogs will not have a good prognosis if they are comatose when brought to the veterinary clinic, have severely acidotic blood (pH less than 7.0), or if they require cardiopulmonary resuscitation (CPR) or mechanical ventilation. Dogs that are conscious upon arrival at the clinic will have a good prognosis, as long as no further complications ensue.