Fluid in the Lungs in Dogs

Pulmonary edema may develop over time and show as a breathing difficulty for your pet only upon exertion. Or rapid accumulation of fluid in the lungs may occur, causing acute respiratory distress. If the alveoli become filled with fluid instead of air, your dog will have reduced breathing capabilities due to low oxygen intake and limited carbon monoxide output. If you sense that your dog is having breathing difficulties, bring him to the veterinarian immediatelyl, as this may be an emergency.

Fluid in the lungs in dogs is also known as pulmonary edema. An abnormal amount of fluid accumulates in the alveoli (air sacs within the lungs where the exchange of carbon monoxide and oxygen take place) and the interstitium (blood vessels and cells that support the alveoli).

Depending upon the reason for the fluid accumulation and the length of time that the breathing difficulty has been developing, signs may vary. If your dog is exhibiting any of these signs, see a veterinarian immediately:

• Coughing
• Weakness
• Crackling noises when breathing
• Rapid intake of air upon exertion
• Showing an effort when breathing
• Blue tongue or lips (cyanosis)
• Collapse

Types

Pulmonary edema can be broken down into two types:

Cardiogenic Pulmonary Edema

• Secondary to left sided congestive heart failure
• Sodium and water retention increase the circulatory volume and venous pressure leading to fluid build-up
• A history of heart trouble (known or unknown) may be present

Noncardiogenic Pulmonary Edema

• Accumulated fluid has a higher concentration of protein, and the capillary pressure is normal
• The trigger for a noncardiogenic event will be trauma, for example.

The causes for fluid accumulation in dogs can be numerous.

Cardiogenic Pulmonary Edema

• High sodium diet
• Dilated cardiomyopathy (enlarged heart)
• Hypertrophic cardiomyopathy (thickening of walls of the heart)
• Mitral valve regurgitation (heart valve does not close properly, allowing blood to flow back into the heart)

Noncardiogenic Pulmonary Edema

• Electrocution
• Trauma to the head
• Secondary disease such as cancer
• Drowning
• Smoke inhalation

The veterinarian may choose to begin with a diagnosis of exclusion to rule out possibilities such as an obstruction, heartworm, or pneumonia. Your pet’s weight will be verified. (Note that cardiac disease often presents with a very underweight pet.) Upon verification, it may be found that your dog may have a fast heart rate and a weak pulse.

The test of choice to diagnose fluid in the lungs is a thoracic x-ray. If your dog has cardiogenic pulmonary edema, your veterinarian may find an enlarged heart, distended pulmonary veins, and fluid in the alveoli.

A chest x-ray that shows fluid throughout the lungs, and without an enlarged heart points to a noncardiogenic diagnosis. The echocardiogram may also be normal.

Measurement of protein in the fluid (possible only through intubation, or if your dog is coughing up fluid) can lead to diagnosis also. Cardiogenic pulmonary edema will show low levels of protein, while noncardiogenic presents with high protein levels in the fluid.

Treatment will depend on the reason for the fluid, but in any case the first step will be to stabilize your dog. Oxygen therapy may be started, along with antibiotics to prevent pneumonia.

Cardiogenic Pulmonary Edema

In this case oxygen, rest and diuretics (to hasten the removal of fluid) will be used. Also, vasodilators (to widen blood cells) might be necessary, depending on the situation. The veterinarian will carefully monitor your pet’s blood pressure, heart rate, and respiratory rate during the hospitalization period. Repeat x-rays may be ordered by the veterinarian in order to observe the lung fluid levels. Heart disease is a chronic problem, so it is possible the edema may return.

Noncardiogenic Pulmonary Edema

Controlling the causative factor is an important part of the treatment protocol in this instance. Depending on the cause and severity, your dog can improve rapidly with oxygen therapy. Antibiotics, intravenous fluids and colloids, diuretics, and anti-inflammatories will be administered as needed, depending on the edema cause. Again, blood pressure, respiratory rate, body temperature, and oxygen saturation will regularly be checked during treatment.

In both cases, your dog will benefit from the least amount of stress possible during hospitalization.

It is very important to distinguish which type of pulmonary edema is affecting your dog in order to determine the appropriate follow-up.

In the case of cardiogenic pulmonary edema, a low sodium diet along with medication to repair and strengthen the heart will be required. Noncardiogenic follow up is less specific, and depends on the origin of the problem. Successful treatment of the underlying disease or trauma is key to recovery.

In both cases, follow-up visits with the veterinarian will be vital for the continued health of your pet. The veterinarian will want to repeat diagnostic tests as necessary (such as x-ray to verify fluid levels) and prescribe any medications needed to hasten recovery. As the owner of a dog who has experienced pulmonary edema, you should always be aware of your pet’s breathing patterns and promptly visit the clinic to discuss irregularities.