Treatment of glomerular and tubular proteinuria in the nephrotic range in a female cat: case report.

The objective is to serve as a descriptive and educational report regarding the case of an eight-year-old spayed mixed-breed cat with nephrotic-range tubular and glomerular lesion, with no history of prior medication use or comorbidities, the main complaint being prostration and sudden weight gain. Physical examination revealed anasarca, moderate dyspnea and paradoxical breathing. Imaging tests revealed bicavitary effusion and subcutaneous edema. Laboratory analyses revealed serum creatinine equal to 3.0 mg/dL, severe hypoalbuminemia of 0.8g/dL, urine specific gravity equal to 1.020 and intense proteinuria (UPC ratio= 13.09). Urinary electrophoresis confirmed proteinuria with both glomerular and tubular involvement. This led to the suspicion of nephrotic syndrome with mixed-origin lesions. Treatment included furosemide, dexamethasone, benazepril, omega-3 fatty acid, mirtazapine and renal diet, in addition to procedures such as paracentesis for drainage. Progressive clinical improvement was observed, with resolution of anasarca by day 21, normalization of albumin by day 37 and a reduction of up to 93.85% in proteinuria nine months after the end of treatment. The patient remained stable, with no recurrence of symptoms. The therapeutic conclusions are limited by the single-case design, although continuous clinical and laboratory monitoring was implemented, aiming to adjust therapeutic management.