Pulmonary edema, the abnormal accumulation of fluid in the tissue, airways, or air sacs (alveoli) of the lungs, may occur along with circulatory disorders (such as congestive heart failure) or in some allergic reactions or infectious diseases. Head trauma can cause pulmonary edema in cats. Labored breathing, with an increased rate, and open-mouth breathing may occur. Animals stand rather than lying down, lie only on their chest, or assume a sitting position. The veterinarian may be able to hear wheezing and crackling sounds in the chest. Oxygen supplementation can provide short-term relief, but treatment of the primary cause is also necessary. Medications called diuretics are typically used to remove excessive fluid from the lungs.