Bloated Abdomen

A bloated abdomen, also called abdominal distension, means a belly that is visibly bulging beyond a pet's normal body outline. It is not one disease; it is a sign. The fullness can come from gas, fluid, an enlarged organ, a mass, or weakness in the abdominal wall. Sometimes the cause is harmless or short-lived, such as pregnancy, a large meal, or intestinal roundworms in a young puppy or kitten. Other times it signals a serious illness that needs prompt veterinary care.

For dogs, the emergency veterinarians worry about most is gastric dilatation-volvulus, or GDV. The stomach fills with gas and can twist on itself. The American College of Veterinary Surgeons describes how that twist compresses the major veins returning blood to the heart, reduces blood flow to the stomach wall, and makes breathing harder. GDV can progress to shock and tissue death within hours. Early signs include restlessness, pacing, drooling, retching without bringing anything up, and a tense or painful belly. GDV mainly affects large and giant breeds. Veterinary Partner reports that dogs over 45 kilograms have an estimated 20 percent lifetime risk, and even with emergency treatment the condition carries a reported mortality rate of 10 to 33 percent. A study in the Journal of the American Veterinary Medical Association found that raised food bowls increased risk by 20 to 52 percent rather than preventing bloat, and research cited by Veterinary Partner indicates lean, deep-chested dogs may be at higher risk than overweight dogs.

Cats rarely develop GDV. A bloated belly in a cat more often comes from fluid collecting inside the abdomen. International Cat Care notes that effusive feline infectious peritonitis, or FIP, can cause a thick, protein-rich fluid to build up in the belly of young cats, producing a gradual and usually painless enlargement. Male cats can also develop a blocked bladder, which shows up as a firm, painful swelling low in the abdomen and needs immediate attention. In unspayed female dogs, a distended abdomen can be pyometra, a life-threatening infection in which the uterus fills with pus.

A swollen belly should not be dismissed as ordinary weight gain. Pets with fluid or organ enlargement sometimes lose muscle along the spine and hips even as the abdomen expands. Signs that need urgent attention include:

• an arched back or the prayer posture
• rapid breathing
• pale gums or a weak pulse
• collapse

Your vet can sort this out with a physical exam, X-rays, or a focused ultrasound scan, and may take a small sample of abdominal fluid to check for infection or bleeding. For GDV, treatment starts with releasing the trapped gas and then surgery to untwist and secure the stomach. If your pet's belly looks enlarged and they seem at all off, call your vet right away instead of waiting.