Also known as abdominal effusion, ascites (pronounced ass-eye-tees), is a condition in cats characterised by the accumulation of fluid in the abdominal cavity.
Most commonly a pale/straw coloured fluid known as transudates (fluids with a low protein and cell content that pass through a membrane or tissue) or exudates (fluid with a high protein content containing cells and cellular substances from the blood vessels), however other fluids such as chyle (highly fatty lymphatic fluid draining from the intestine), blood and urine can also occur.
The abdominal cavity is located below the chest and is separated by the diaphragm, a thin sheet of muscle and tendon. Several organs are contained within the abdomen including the liver, spleen, stomach, pancreas and kidneys. A membrane known as the peritoneum lines the abdominal cavity.
Ascites is indicative of an underlying disease, the most common being:
- Right-sided congestive heart failure - Dilated cardiomyopathy, hypertrophic cardiomyopathy, congenital anomaly. As the heart becomes less efficient at pumping, fluid begins to build up which in turn builds up pressure in the blood vessels, which forces them to leak fluid.
- Peritonitis (inflammation of the peritoneum) - Feline infectious peritonitis, bacterial peritonitis, chylous peritonitis. The immune response mounted by the cat damages the blood vessels, causing them to leak fluid.
- Cancer within the abdomen - Some cancers can cause a blockage to the lymphatic system, (which drains fluids that are excreted via the urine) when a blockage occurs, excess fluid can not drain properly causing fluid to build up. Tumours may also rupture, leaking fluid into the abdomen.
- Hypoalbuminemia - Liver disease can lead to a condition known as hypoalbuminemia. Albumin is a protein which is predominantly produced and secreted by the liver, the capacity of the liver to produce albumin drops as the liver fails. Kidney disease - Albumin is also lost when kidney function drops, the kidneys are no longer as effective at filtering and returning albumin to the body and instead excreting it out of the body via the urine. In both cases, decreased albumin levels lead to a drop in oncotic pressure causes fluid to leak out of the blood vessels, causing ascites.
- Hemorrhage/bleeding disorders: Trauma can lead to an accumulation of blood within the abdomen (hemoabdomen) ingestion of rodenticide can also lead to blood clot disorders, resulting in bleeding into the abdomen.
- A ruptured bladder will result to urine entering the abdomen (known as uroabdomen).
- Chylous ascites (chyloabdomen) is uncommon, but can occur as a result of trauma, heart failure, heartworm or tumours.
What are the symptoms of ascites in cats?
Symptoms may vary depending on the underlying cause of ascites and the amount of fluid in the abdomen. It may have a slow or sudden onset.
- Swollen abdomen.
- Abdominal pain and/or discomfort.
- Difficulty breathing.
- Weight gain.
How is ascites diagnosed?
Your veterinarian will perform a physical examination of your cat and obtain a medical history from you. Accompanying symptoms may help to narrow down the cause.
He will wish to perform some diagnostic tests including:
Chemistry profile - To evaluate for elevated liver enzymes, hypoalbuminemia, low BUN (blood urea nitrogen) which can all point towards liver disease.
Peritoneal fluid analysis - To determine the type of fluid within the abdomen (transudates, exudates, blood, urine, chyle). This can help your veterinarian narrow down the underlying cause.
Urinalysis - To evaluate the kidney function.
Chest x-rays - To evaluate the heart and lungs and look for tumours.
ECG - To evaluate the heart function for abnormalities.
Abdominal ultrasound to evaluate the organs.
Biopsy - If cancer is suspected, your veterinarian will take a tissue sample for analysis.
How is ascites treated?
Treating the underlying cause, where possible. See specific articles for treatments.
Abdominocentesis - Removal of the fluid within the peritoneal cavity via a catheter, this will help to improve his breathing by reducing pressure on the diaphragm.
Diuretics are medications help to promote the production of urine which assists in flushing excess fluids out of the body.
Dandelion extract may also be recommended to help prevent fluid build-up.