/ PAPER Development and progression of proteinuria in dogs treated with masitinib for neoplasia: 28 cases (2010-2019) M. Kuijlaars1,*, J. Helm* and A. McBrearty* a.com *Small Animal Hospital, University of Glasgow, Glasgow, Scotland, G611QH, UK 1Corresponding author email:
[email protected] v OBJECTIVES: To describe the incidence, severity and progression of proteinuria over the first 6 months of masitinib treatment in tumour-bearing dogs without pre-existing proteinuria. To describe the effect of treatment on urine protein:creatinine and renal parameters in patients with pre-existing proteinuria. MATERIALS AND METHODS: Records were reviewed from patients receiving masitinib for neoplasms between June 1, 2010, and May 5, 2019. Patients without pre-treatment and at least one urine protein:creatinine after ≥7 days treatment were excluded. Signalment, tumours and concurrent diseas- es, treatments, haematology, biochemistry and urinalysis results before, during and after treatment for up to 202 days were collected. Patient visits were grouped into six timepoints for analysis. .bsa RESULTS: Twenty-eight dogs were included. Eighteen percent of dogs non-proteinuric at baseline (four of 22) developed proteinuria during treatment, all within 1 month of treatment initiation. One dog developed hypoalbuminaemia, none developed oedema or ascites, azotaemia or were euthana- sed/died due to proteinuria. Masitinib was immediately discontinued in both dogs in which urine protein:creatinine greater than 2.0 was detected and in both, proteinuria improved. Six dogs with pre-treatment proteinuria were treated with masitinib, significant worsening of protein- uria did not occur. Neither azotaemia nor severe hypoalbuminaemia occurred. CLINICAL SIGNIFICANCE: Proteinuria, when it occurs, tends to develop within 1 month of masitinib com- mencement and may progress rapidly.