Estimation of glomerular filtration rate in dogs by a single-blood sample method involving iodixanol

To establish a simplified single-blood-sample method (SBSM) involving iodixanol to estimate glomerular filtration rate (GFR) in dogs and compare data provided by that procedure with data provided by a conventional multiple-blood-sample method (MBSM) involving inulin.

26 healthy dogs and 36 dogs with naturally occurring renal disease.

Dogs were used in various preliminary experiments to establish protocols for the SBSM and the MBSM of GFR estimation. To evaluate the relationship between GFRs obtained by the SBSM and the MBSM each involving iodixanol, iodixanol (40 mg of I/kg) was administered IV to 26 healthy dogs and 36 dogs with renal disease; blood sample collection was performed before and at 60, 90, and 120 minutes after the injection. To evaluate the relationship between GFRs obtained by the SBSM involving iodixanol and the MBSM involving inulin, iodixanol (40 mg of I/kg) and inulin (50 mg/kg) were coadministered IV to 22 healthy dogs and 3 dogs with renal disease, followed by blood sample collection 30, 60, 90, and 120 minutes later. Serum iodixanol and inulin concentrations were separately determined by reverse-phase high-performance liquid chromatography.

Findings revealed a correlation (r = 0.99) between GFR estimated by the SBSM and MBSM each involving iodixanol. Likewise, GFR estimated by the SBSM involving iodixanol was correlated (r = 0.89) with that estimated by the MBSM involving inulin.

Results indicated that the SBSM involving iodixanol can be applied to estimate GFR in dogs, instead of use of an MBSM.