What Is Edema in Dogs?

Edema is commonly thought of as swelling, but it’s actually more complicated than that.

Edema is the accumulation of abnormally large amounts of fluids in the tissues between the body’s cells—and when this fluid accumulates, swelling is the visual result.

This swelling occurs either because too much fluid moves from the blood vessels into the tissues or because not enough fluid moves from the tissues back into the blood vessels. Both scenarios result in a fluid imbalance. Edema also commonly occurs as a side effect of significant disease such as heart failure, kidney disease, liver disease, or malnutrition.

Simple swelling is also an abnormal fluid accumulation and imbalance. But traditionally, we think of swelling as caused by inflammation, such as from an injury, trauma, or tumor. Edema and swelling are often terms used interchangeably, and edema does cause swelling—but with edema, significant diseases are often involved.

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Symptoms of Edema in Dogs

Thankfully, your dog’s other symptoms can help identify the underlying cause of edema.

If an animal has swelling in just one small part of their body, such as part of a leg or one side of the face, inflammation is usually the underlying cause.

Sometimes, the dog will just look puffy all over, as if their entire body is swollen. This can happen when the body doesn’t have adequate protein, has too much sodium, or if there is a severe bacterial infection.

Another common symptom is a very swollen abdomen, sometimes looking as though the dog has swallowed a large ball. This can happen because of edema (fluid accumulation), but it’s more commonly associated with organ swelling or the accumulation of blood in the abdomen. When it is just fluid, heart disease is one of the most common causes of this.

Most commonly, the swelling isn’t visible—but signs of the fluid show up in different forms, such as difficulty breathing (caused by pulmonary edema or effusion, aka fluid in the chest) or neurologic symptoms/seizures (cerebral edema, or fluid in the brain cavity). Because the early signs can be more subtle, these can be the most challenging cases.

Causes of Edema in Dogs

Edema caused by inflammation is usually less serious than other forms of edema. Once the cause of the swelling is diagnosed and identified, the inflammation can be resolved, which usually also eliminates the edema.

Other forms of edema are much more significant and serious. Fluid in the abdomen is most commonly caused by heart disease, liver disease, kidney failure, or cancer. Fluid in the lungs occurs frequently with heart disease. Fluid in the nervous system can be the result of trauma, toxins, or severe metabolic disorders such as diabetes and electrolyte abnormalities.

How Do Vets Diagnose Edema in Dogs?

The first thing a veterinarian will do is take a thorough history and conduct a complete physical examination. This combination will often give enough information to know where to start the diagnostic testing.

Most dogs will need a complete blood count, biochemistry profile, and urinalysis. Some dogs will also need a thyroid test.

Many times, a veterinarian will request permission to aspirate some of the fluid for examination. This can be particularly useful when fluid has accumulated in the chest or abdomen, but other areas—such as the central nervous system and joints—can also have fluid removed for analysis.

Often, X-rays and ultrasound examination are also useful.

Getting an answer for the edema and a treatment plan often requires a battery of tests, so your veterinarian can be sure of a diagnosis and select the best options moving forward.

Treatment for Edema in Dogs

In all cases, treatment for edema will depend on the underlying cause. If the swelling was caused by inflammation, removing the cause of the inflammation and treating with anti-inflammatories is the likely strategy.

Edema secondary to organ failure (heart disease, liver disease, or kidney disease) is more complicated, in that the key to getting rid of the fluid will depend on properly diagnosing and treating the underlying disease.

For example, if there is heart disease, an echocardiogram is likely needed to get a full diagnosis. The treatment will then require a combination of drugs to help the heart, as well as additional medications to reduce fluid buildup.

Dogs with cerebral edema may require a CT scan or MRI to look for the underlying cause, and may need to have some fluid removed and examined. Once again, treatment will depend on diagnosis. It may involve a combination of antibiotics, anti-inflammatories, and anti-seizure medications, as well as drugs tailored to remove the fluid.

Recovery and Management of Edema in Dogs

Many cases of edema will require hospital stays. Edema caused by inflammation is often the quickest and simplest to resolve, and can often be done while your pet is at home. Edema caused by organ failure or that affects the nervous system, however, can require multiple-day hospital stays.

Almost all cases of edema will require care and medications at home after the office visit, while others—such as edema from heart failure—will likely require lifelong treatment.

Any edema in dogs—other than that which affects a small area of the body, such as a single leg or ear—is usually considered serious, requiring thorough investigation and aggressive treatment. Once the underlying cause is found, however, it often becomes easier to develop an appropriate treatment plan.

Featured Image: Adobe/Chlorophylle

Sandra C. Mitchell, DVM, DABVP


Sandra C. Mitchell, DVM, DABVP


Sandra Mitchell is a 1995 graduate of the New York State College of Veterinary Medicine. Since graduation, she has worked in many fields...

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