Toceranib phosphate-associated nephrotic syndrome in a dog: a case report

Nephrotic syndrome (NS) is rare in dogs and is characterized by concurrent clinical findings of proteinuria, hyperlipidemia, hypoalbuminemia, and edema. NS has been reported in humans receiving tyrosine kinase inhibitors (TKI) and in dogs receiving masitinib. This is the first report of NS in a dog receiving toceranib phosphate.

An 8-year-old, female, spayed Labrador retriever was diagnosed with a 10 cm mast cell tumor on the left lateral abdomen. After completion of a 12-week vinblastine and prednisone protocol, she began treatment with toceranib phosphate (2.6 mg/kg by mouth, every other day). Proteinuria was documented prior to starting toceranib. On day 426 after diagnosis (day 328 of toceranib phosphate treatment), the dog was evaluated for diarrhea, lethargy and anorexia. On physical examination, dependent edema was noted on the ventral chest and abdomen, and sterile neutrophilic inflammation was aspirated from a 2.3 cm splenic nodule. The following laboratory values were reported: albumin < 1.5 g/dL; cholesterol 378 mg/dl and urine protein to creatinine ratio of 3.79. The patient was diagnosed with NS, and treatment with toceranib phosphate was discontinued. Low-dose aspirin was started in addition to an increased dosage of enalapril (0.47 mg/kg q12hr). No other therapy was instituted. The dog improved clinically, and laboratory values returned to near normal over the 8-week follow-up. She was euthanized 1399 days after discontinuing toceranib phosphate with progressive disease.

Nephrotic syndrome is a potential adverse event associated with the drug toceranib phosphate which may be reversible with discontinuation of treatment. Careful monitoring of urine protein, serum biochemistry, blood pressure and patient weight is advisable during treatment with toceranib phosphate.