This is a description of an intact female Rottweiler that was referred for treatment of pyometra. The dog was further diagnosed with a splenic mass and was surgically treated via uncomplicated ovariohysterectomy and spenectomy. Post-operatively, the patient showed signs of systemic inflammation, became severely hypoalbuminemic, and suffered consequences of low colloid oncotic pressure (COP) including pulmonary edema, pleural effusion and peripheral edema. The patient was treated with 25% human serum albumin to alleviate the clinical signs of low COP and ultimately made a full recovery.