What Is Ascites?
Ascites, also called abdominal effusion, is an abnormal buildup of fluid in the abdomen, the space around the stomach, intestines, liver and other organs. It makes the belly look swollen or pot-bellied, often while the back and hips lose muscle. Ascites is a sign of an underlying problem, not a diagnosis on its own, and finding the cause is the key to treating it.
Emergency signs
A belly that swells quickly with pale gums, weakness or collapse can mean internal bleeding. A tight belly with unproductive retching in a dog can be bloat. Both need an emergency vet now.
Common Causes
- Heart failure on the right side of the heart, from conditions such as dilated cardiomyopathy, pericardial effusion or advanced heartworm disease; see heartworm prevention
- Liver disease, which can lower blood protein and raise pressure in the veins draining the gut; see cat liver disease
- Protein loss through the gut or kidneys; see protein-losing enteropathy, lymphangiectasia and protein-losing nephropathy
- Bleeding into the abdomen, often from a ruptured tumor such as hemangiosarcoma, trauma or rat poison
- Feline infectious peritonitis (FIP) in cats, which typically produces thick, straw-yellow fluid; see FIP
- Cancer, infection (peritonitis) or a ruptured bladder
Signs
- A rounded, swollen or sagging belly, sometimes with a fluid “wave” feel
- Weight loss along the spine and hips while the belly grows
- Faster or harder breathing, because the fluid presses on the diaphragm
- Tiredness, reduced appetite, reluctance to lie down comfortably
- Signs of the cause, such as coughing, yellow gums, vomiting or diarrhea
Not Every Big Belly Is Ascites
Weight gain, pregnancy, an enlarged liver from Cushing’s disease, worms in puppies and kittens (see roundworms) and bloat (GDV) can all change the belly’s shape. A vet exam and ultrasound tell them apart.
Diagnosis
Vets confirm fluid with an ultrasound, then usually draw a small sample with a fine needle (abdominocentesis). The color, protein level and cells in the fluid point toward the cause: clear, watery fluid suggests low protein; blood suggests bleeding; cloudy fluid suggests infection or inflammation. Bloodwork, urine tests, chest X-rays and a heart scan often follow, and complex cases may be referred to an internal medicine or cardiology specialist.
Treatment
- Treating the underlying disease, which is what controls the fluid long term
- Diuretics, especially for heart and liver causes
- Draining fluid with a needle if it makes breathing hard; it often returns if the cause is not controlled
- A lower-sodium diet when your vet recommends one
- Emergency surgery or transfusion for active internal bleeding
Frequently Asked Questions
Is ascites painful?
The fluid itself is usually more uncomfortable than painful, mainly by making breathing and lying down harder. Some causes, such as peritonitis or pancreatitis, are painful.
Can ascites be cured?
It can disappear completely when the cause is treatable, such as some infections or protein loss that responds to diet and medication. With heart failure or cancer, the goal is usually long-term control and comfort.
How quickly should my pet be seen?
Within a day or two for a slowly growing belly in a bright pet, and immediately if the swelling is sudden or your pet is weak, pale or breathing hard. Our guide to emergency vet vs regular vet can help you decide.
If your pet’s belly is getting bigger without an obvious reason, book a check. Find a veterinary clinic near you for an exam.