Objective: To obtain Doppler ultrasonographic images of renal arteries in horses and to establish reference range values for systolic and diastolic renal arterial blood flow and resistive indices. Also to determine whether Doppler ultrasonography could be used in horses to detect changes in renal blood flow after IV administration of furosemide.
Animals: 11 clinically normal adult horses.
Procedures: Pulsed-wave Doppler examinations were performed on arcuate arteries of 5 sedated horses. Continuous-wave Doppler examinations were performed on pyelorenal arteries in 7 nonsedated horses and were repeated in 6 horses after furosemide administration. Peak-systolic velocity (SV) and end-diastolic velocity (EDV) were measured and the resistive indices (RI) were calculated.
Results: Using pulse-wave Doppler ultrasonography in sedated horses, arcuate arteries were determined to have a SV of 0.406 +/- 0.116 m/s (mean +/- SD), EDV of 0.184 +/- 0.057 m/s, and RI of 0.549 +/- 0.044. Using continuous-wave Doppler ultrasonography in nonsedated horses, pyelorenal arteries were determined to have SV of 1.047 +/- 0.009 m/s, EDV of 0.510 +/- 0.006 m/s, and RI of 0.512 +/- 0.004. Doppler waveforms from the arcuate and pyelorenal arteries had a low resistance flow pattern, characterized by a systolic peak followed by a continuous antegrade diastolic flow. After furosemide administration, the pyelorenal arterial velocities increased, but the RI remained unchanged.
Conclusions: Doppler ultrasonography may be used to record renal blood flow in horses and to detect changes following furosemide administration.
Clinical relevance: Doppler ultrasonographic images may assist in the diagnosis of renal diseases that affect either blood flow or Doppler waveform.