Objective: To evaluate urine protein content in dogs with pituitary-dependent hyperadrenocorticism (PDHAC) and to determine the effect of mitotane administration on proteinuria in these dogs.
Design: Prospective case series.
Animals: 16 dogs with PDHAC were evaluated (age range, 7 to 14 years; mean age, 10 years; female-to-male ratio, 2.2:1).
Procedure: Urine protein-to-creatinine (UPC) ratios and 24-hour urine protein excretion (24-hour UPE) values were measured before beginning treatment with mitotane and after establishing appropriate maintenance treatment.
Results: Before treatment, UPC ratios ranged from 0.03 to 4.16 (16 dogs, median, 0.695; reference range value, UPC ratio < 0.5; questionable value, UPC ratio > 0.5 but < 1.0; high value, UPC ratio > 1.0). Seven dogs had proteinuria with UPC ratios > 1.0. Twenty-four-hour UPE values ranged from 0.67 to 61.7 mg/kg of body weight/d (0.30 to 28.0 mg/lb/d; 13 dogs, median, 9.7 mg/kg/d [4.4 mg/lb/d]; reference value, 24-hour UPE value, < 20 mg/kg/d [9.1 mg/lb/d]). Five dogs with high UPC ratios also had high values for 24-hour UPE. After establishment of maintenance treatment with mitotane (median, 7 weeks; mean, 7.3 weeks), UPC ratios ranged from 0.02 to 6.5 (16 dogs, median, 0.36). Five dogs continued to have high UPC ratios. Values of 24-hour UPE ranged from 0.47 to 122 mg/kg/d (0.21 to 55.5 mg/lb/d; 13 dogs, median, 5.1 mg/kg/d [2.3 mg/lb/d]). Three dogs continued to have high 24-hour UPE values. Significant differences were not found between dogs before and after treatment with mitotane in terms of UPC ratios or 24-hour UPE values.
Clinical implications: In dogs with PDHAC and proteinuria, UPC ratios should be monitored closely. Some dogs with PDHAC may have a decrease in urine protein content following treatment with mitotane. We suggest that renal biopsies be considered in those dogs with progressive increases in UPC ratios.