Ascites is a fluid buildup in the abdominal cavity. Paracentesis , (the removal of the abdominal fluid) can be not only therapeutic but diagnostic. In many cases a fluid analysis can be done that may help determine the cause, but the ultrasound seemed to give some direction.
In the case of a cat, one possibility is feline infectious peritonitis, which is a viral disease. Often accompanied by high fever, it is usually fatal. Your cat’s age makes me think her ascites was probably not due to FIP but rather a liver condition, some kind of abdominal cancer or heart failure. Blood work may have been diagnostic but ultimately either a cardiac evaluation or abdominal biopsies would have most likely given answers. Had the cause been identified, treatment may have consisted of various medications starting with a diuretic, low-salt diet and periodic abdominal fluid removal.
The problem is that, despite getting answers, sometimes we can still do nothing to improve a situation and that may well have been the case with your cat.
John de Jong, D.V.M., is the owner/operator of Boston Mobile Veterinary Clinic and CEO/director at Boston Animal Hospital.