Pulmonary Edema in Dogs

Animals suffering from this may show signs such as labored or open-mouthed breathing,  hesitance to lay down, or favor lying on their chest. Upon thoracic auscultation, wheezing or crackling sounds may be heard. Pulmonary edema can be caused by many different conditions such as upper airway obstruction, allergic reactions, head trauma, or may occur along with circulatory disorders.

Pulmonary edema is the accumulation of an abnormal amount of fluid in the lung tissue, airways or air sacs. This condition is usually divided into cardiogenic and non-cardiogenic forms and can be clinically insignificant or life-threatening.

• Increased respiratory rate or respiratory distress
• Acute distress 
• Jugular vein distension
• Cardiac abnormalities such as murmur or arrhythmia 
• Weak pulse 
• Crackles in the thorax
• Burns to the mouth in cases of electric cord injury 
• Loud or labored breathing 
• Fever 
• Coughing
• Cyanosis

Risk Factors for this condition include:

• Chronic heart disease
• Poor diet high in sodium
• Excessive fluid therapy treatment 
• Obesity 
• Cardiogenic pulmonary edema is caused by increased pulmonary capillary hydrostatic pressure due to heart failure on the left side; this is often caused by chronic conditions such as dilated cardiomyopathy
• Non-cardiogenic pulmonary edema is caused by an increase in permeability of the alveolar-capillary barrier; this form can be caused by underlying conditions such as sepsis, severe neurologic stimulation or electric cord shock

Your veterinarian will perform a full physical examination, with care not to stress your pet, especially if dyspnea has occurred. If your pet requires immediate oxygen therapy it may be necessary to perform a physical examination in stages, providing oxygen between examinations. Your veterinarian will listen to your pet’s respiration using a stethoscope; in cases of pulmonary edema a distinctive crackling sound may be heard. Your pet’s mucous membranes will be examined for signs of burns that may indicate burns from an electric cord.

If your pet is stable a thoracic radiograph may be performed, with your dog placed on their back. This radiograph may show signs of pulmonary edema such as increased interstitial or alveolar opacity. In dogs that are suffering from cardiogenic pulmonary edema, cardiomegaly and distended pulmonary veins may also be seen. 

Pulmonary capillary wedge pressure may also be taken to determine if the cause is cardiogenic or noncardiogenic’. This is measured by inserting a balloon tipped catheter through the jugular and heart, into the pulmonary artery. The balloon is then inflated and measurements taken while it is in place. A PCWP that measures higher than 18 mmHg is considered diagnostic of cardiac dysfunction. The edema fluid may also be tested to measure the protein content, as cardiogenic edema fluid is low, while noncardiogenic contains high levels, however, this is often not possible unless the pet is intubated or coughing the fluid up. 

Other diagnostic tests that may be carried out to determine the underlying cause of the condition are a complete blood count, urinalysis, serum chemistry and blood gas analysis, and full neurological examination.

If your pet is suffering from respiratory distress, oxygen supplementation may be required. This can be given by mask, flow by oxygen or by placing your pet in an oxygen cage. In some cases, a nasal tube may be placed through the nasal cavity.

If your pet is suffering from severe respiratory distress they may require sedation, intubation with an endotracheal tube and positive-pressure ventilation. 

In cases of cardiogenic pulmonary edema diuretics and vasodilators may also be given. Your veterinarian will utilise this therapy with extreme caution and your pet will be carefully monitored for signs of hypotension. Anti-arrhythmic therapy may be given if your pet is experiencing tachyarrhythmia (abnormal heart rhythm).

For animals suffering from noncardiogenic pulmonary edema, the treatment may include anti-inflammatories and diuretics. Depending on the underlying cause, rest in a well oxygenated area may be sufficient treatment. Your pet may require sedation with an opioid to support respiration and decrease stress.

The prognosis for noncardiogenic edema varies from good to grave, while the prognosis of for cardiogenic edema may be guarded, with pets who survive expected to require life-long cardiac therapy. 

In both cases, the pet should receive careful monitoring during recovery of their respiratory rate and effort, heart rate, temperature and oxygen saturation. Your pet should be offered highly palatable food and given as much comfort as possible to reduce stress. If possible, keep away from other animals and bring items in from home such as bedding to provide comfort. 

If your pet is recumbent, ensure they are provided with soft, absorbent bedding that is changed often and they are regularly turned to prevent urine scalding or pressure sores developing.