In dogs, a swollen or distended abdomen may be a sign of a significant medical condition or disease, or it may be due to something less worrying, such as a resolvable bacterial infection or parasites. Due to the possibility of organ failure or breathing difficulty, however, any swelling in the abdominal area warrants an immediate veterinary visit. 

Some underlying causes of a distended abdomen are potentially fatal and indicate a dysfunction or disease process involving a major organ such as the heart, lungs or kidneys. Additionally, most cases of abdominal distension cause pain and discomfort that may be alleviated with treatment. 

One probable cause of abdominal distension in dogs is a condition called ascites (or abdominal effusion), which is a general term that refers to the build-up of fluid in a dog’s abdominal cavity. In a healthy animal, there should be no more than a nominal amount of fluid present in the abdominal cavity. The purpose of this fluid is to keep the organs “gliding” smoothly around each other. In fact, the amount of fluid in a healthy dog’s abdomen should be low enough not to appear on radiography. Any imaging that reveals the presence of free fluid is an indication of a serious health problem. Ascites is a symptom of many other conditions, including liver and cardiac disease, specifically congestive heart failure (CHF). In congestive heart failure, the heart cannot pump enough blood throughout the body, causing fluid to swell in tissues both in the lungs and stomach. The dog’s overall prognosis will depend on the source of the swelling or ascites. 

Another possible cause for the abdominal distension is a pooling of blood. This could occur after e.g. a splenic tumour rupture, coagulation defect or trauma.

Rapid-pooling gas, or “bloat,” is another emergent cause of abdominal distention in a canine. In the veterinary world, bloat is an alarming term that signifies something far different than feeling full after a big dinner. Bloat, in a dog, will cause the abdomen to become untenably swollen and tight. The abdomen may take on an uneven appearance in which one part of the abdomen distends beyond another. If your dog appears to be bloated, this is a highly emergent situation, and the dog must get veterinary care immediately. 

Other common causes of abdominal distension in dogs include pregnancy, which is distinguishable from other conditions due to the presence of swollen mammary glands and teats. Obesity is another possibility; in this case, the stomach should be soft and fat should be visible elsewhere on the body, not only in the stomach area.

Some medical conditions such as Cushing's disease are known to cause abdominal swelling due to the weakened abdominal muscles and enlarged liver.

Tumours growing in the abdomen will inevitably result in some visible swelling once they reach a certain size.

Puppies that are bloated are commonly infested with parasites (intestinal worms).

In canines, a distended abdomen may signify a disease or dysfunction related to a major organ such as the heart, or another condition such as pregnancy or obesity.

Clinical signs associated with distended abdomen in dogs include:

The veterinarian may make an initial diagnosis based upon the dog’s presentation of symptoms at the physical examination. Radiography and ultrasounds may confirm the presence of fluid in the abdomen, or perhaps reveal another cause. Blood (CBC), urine and sample of (if any) fluid will be subject to laboratory testing, and may offer insight into the dog’s overall condition. Other testing will be performed based on the veterinarian’s suspicions.

Treatment options will depend upon the cause of the abdominal distension, and any underlying conditions. If there is a fluid buildup, that will have to be eliminated; however, without treating the source of the ascites, improvement is not likely. Treatment examples would be:

As with any illness, provide your dog with a quiet place to rest and heal. Follow veterinary advice regarding any nutritional changes, and follow-up medications. The dog’s prognosis will depend upon the cause of the distension. Keep a watchful eye on the abdominal area, and notify the veterinarian if changes are noted.

Conditions related to a distended abdomen can be expensive to treat. To avoid high vet care expenses, secure pet health insurance today. The sooner you insure your pet, the more protection you’ll have from unexpected vet costs.