Overview of Canine Abdominal Distension
In dogs, one cause of abdominal distension is fluid accumulation. The types of fluids include blood from internal hemorrhage (bleeding), urine from a tear in the urinary tract, exudate (cellular fluids similar to pus) from infection as with feline infectious peritonitis, and transudates (clear fluids), that are leaked from vessels.
Another cause of abdominal distension is enlargement of any abdominal organ including the liver, kidneys, or spleen. Distension of the stomach with air (“bloating“) or fluid or distension of the uterus (womb) during pregnancy, can result in abdominal distension.
Tumors within the abdomen can also cause abdominal distension. The tumor may be malignant (an invasive cancer), or benign, (abnormal but not spreading to other tissues). Tumors can involve any of the abdominal organs, including the intestines or lymph nodes (glands).
Loss of abdominal muscle tone, with or without significant weight gain, also can lead to abdominal distension.
Pressure from the abdomen pushing into the chest may make breathing more difficult and pressure within the abdomen may decrease the appetite. NOTE: It is important to recognize abdominal distension because it can be a symptom of potentially life-threatening diseases and should be investigated thoroughly.
What to Watch For
- Sudden abdominal enlargement. Treat this as a medical emergency especially if associated with vomiting, retching, sudden weakness or collapse.
- Distension that occurs over days to weeks. This requires prompt medical attention.
- Slowly developing abdominal enlargement. This should be investigated if it is accompanied by loss of muscle or fat in other regions of the body, decreased appetite, vomiting or diarrhea, changes in urinary or bowel habits, or a diminished activity level.
Diagnosis of Abdominal Distension in Dogs
Veterinary care should include diagnostic tests to determine the cause of the abdominal distension and provide information on which to base recommendations for treatment. Diagnostic tests that your veterinarian may wish to perform include:
- A complete medical history and physical examination
- Abdominal radiographs (X-rays)
- Abdominal ultrasonography
- Abdominocentesis (the removal of fluid from the abdomen using a needle)
- Thoracic radiographs (chest X-rays)
- Blood tests such as biochemistry analysis, a complete blood count (CBC), a PCV (packed cell volume) and TP (total protein)
- Other specific tests, like liver function, evaluation for feline coronavirus exposure or biopsy of affected tissues or organs
Treatment of Abdominal Distension in Dogs
Treatment for abdominal distension is dependent upon the underlying cause (diagnosis). Treatment may include:
- Abdominocentesis or drainage of fluid from the abdomen. If fluid distension causes pressure on the diaphragm (the muscular membrane separating the chest and abdomen) and impairs breathing, fluid may be drained from the abdomen with a needle. Fluid accumulation that does not interfere with breathing is not routinely removed.
- Diuretic administration. Certain types of fluid accumulation can be lessened with diuretic administration, which increases urination.
- Surgery. Some causes of abdominal enlargement, including ruptured abdominal organs, must be treated surgically.
If you notice abdominal distension and your dog is acting sick, call your veterinarian. If abdominal distension is associated with vomiting, wretching or collapse, call your veterinarian immediately. These symptoms can be life-threatening.
In-depth Information on Abdominal Distension in Dogs
The abdominal cavity contains vital organs such as the stomach and intestines, liver, spleen, pancreas, kidneys and urinary bladder. It also contains numerous blood vessels, lymph vessels and lymph nodes are also present in the abdominal cavity and is lined with a thin, specialized membrane (the peritoneum) that contains the contents within a sterile environment.
Causes of Abdominal Distension in Dogs
Abdominal distension can be caused by fat accumulation, fluid accumulation in the peritoneal space, enlargement of abdominal organs or weakness of the abdominal muscles. The fluids that cause abdominal distension can be blood, urine, exudate, transudate or any combination of these.
Causes of these different fluid types are listed below:
Blood can fill the abdomen because of trauma, erosion of blood vessels, failure to form blood clots normally, or tumors causing organs to rupture.
Urine can fill the abdomen and cause distension. Rupture of the urinary tract is generally the result of trauma (such as being hit by a car).
Exudates are thick, cellular fluids. These fluids often result from infection within the abdominal cavity. Dogs may develop exudate in response to bacterial infection as a result of a penetrating injury or a tear in the gastrointestinal tract. This can occur in dogs with a string-type foreign body that “saws” its way through the intestine. Exudates may also accompany cancers of the abdomen (neoplastic effusion) or result from obstruction to drainage of lymphatic fluid (chylous effusion). Lymphatic fluids are fluids that surround cells and are collected and transported by lymph vessels into the bloodstream.
Transudates are clear fluids, without many cells or much protein, resulting from pressure blocking normal blood flow or from decreases in the protein (albumin), which holds water in the blood. Examples of processes likely to produce transudates include:
- Right-sided heart failure, in which blood “backs up” in the vessels because it cannot enter the heart easily, and some liquid from the blood is forced out of the vessels. Congenital heart disease, heart muscle disease (cardiomyopathy), arrhythmia (abnormal electrical activity of the heart), and diseases of the pericardium are also potential causes of right-sided heart failure in dogs. However, heart failure is a very uncommon cause of abdominal fluid accumulation in dogs.
- Cirrhosis, or fibrosis of the liver, also causes changes in pressure to the blood vessels within the abdomen. In addition, cirrhosis results in liver failure. When the liver fails, it does not produce normal amounts of albumin (blood protein).
- Loss of albumin through the kidneys (or the gastrointestinal tract (lymphangectasia or protein loosing enteropathy) can lead to very low albumin levels. When albumin levels are too low, liquid is not held within the blood and can leak out into the abdomen. This situation is very uncommon in dogs.
Enlargement of any abdominal organ can cause distension. Enlargement of the liver, kidneys or spleen may be due to obstructions of fluid flow (either blood flow or urine flow) or infiltration with cells (cancer or leukemia cells or inflammatory blood cells).