In humans with liver disease, renal resistive index (RI) and pulsatility index (PI) as measured by Doppler ultrasound technique may be increased. These values may be monitored to obtain prognostic information. Hepatic disease is also reportedly a cause of systemic hypertension in dogs, but renal involvement has not been reported. The authors of this study postulated that if the cause of systemic hypertension in these dogs is related to a lack of vasodepressor effect, this could be detected as increased renal vascular resistance and RI and PI would increase. Twenty dogs with hepatic disease were included in the study. Physical examinations, blood analysis, urinalysis, abdominal ultrasonography, and, in some cases, histology or cytology of the liver were performed. Blood pressure and renal index values were obtained via Doppler device. Mean RI, PI, and systolic blood pressure significantly differed between dogs with hepatic disease and healthy dogs. A significant correlation was also found between alkaline phosphatase and RI and PI, although no other correlation was found between the renal indices and arterial blood pressure, heart rate, or other biochemical parameters. The authors concluded that renal vascular resistance, as measured by RI and PI, does increase in some dogs with hepatic disease and that further studies might help determine the correlation of RI and PI with other parameters for their value in predicting severity and prognosis.

COMMENTARY: In this study, renal vascular resistance, evaluated by means of RI and PI, increased in some dogs with hepatic disease. Increased renal vascular resistance has been reported in both dogs and cats with renal disease. Other parameters to measure renal disease, such as an increase in creatinine, often are not seen until the renal disease is advanced, so this may be a good way to monitor for renal disease in patients with liver disease. More studies with larger groups of animals will help determine clinical usefulness of determining RI and PI.

Increased renal vascular resistance in dogs with hepatic disease. Novellas R, Ruiz de Gopegui R, Espada Y. VET J doi: 10.1016/j.tvjl.2007.07.026.