The interaction between the cardiac and renal systems is important in determining blood pressure and blood volume, both of which play a role in the vasomotor system and fluid balance. Cardiorenal syndrome (CRS) occurs as a result of a disparity in correlation between the two. In veterinary medicine, cardiovascular-renal axis disorder (CvRD) lacks pathologically and etiologically specific data, but shares common pathophysiological patterns with CRS and CvRD in humans. CvRD is structural or functional damage caused by diseases of the heart or kidneys, or toxins or drugs, resulting in the disruption of normal interactions between these organs and the destruction of one or both organs. The aim of this study is to compare the long-term changes in various indicators, including hypertension, proteinuria and echocardiographic parameters, before and after administration of telmisartan in cats with CvRD. This study found a clear gradual decrease in Urine protein to creatinine (UP/C) ratio and left atrium (LA) diameter in cats with CvRD, after administration of telmisartan. UP/C ratio (p<0.001) was found to decrease significantly over time, after administration of telmisartan. UP/C ratio before telmisartan administration was 0.39 ± 0.255 (Day 0) and 0.29 ± 0.056 on day 30 (Day 30), 0.28 ± 0.040 on day 60 (Day 60), and 0.20 ± 0.128 on day 90 (Day 90) after administration, respectively. LA diameter before telmisartan administration was 17.9 mm ± 1.6 before telmisartan administration (Day 0) and 17.4 mm ± 1.8 on day 30 (Day 30), 16.1 mm ± 1.6 on day 60 (Day 60), and 15.7 mm ± 1.7 on day 90 (Day 90) after administration, respectively. Oral administration of telmisartan to cats with CvRD is effective in improving proteinuria and LA diameter, which is a positive aspect of long-term survival in cats with CvRD.

Angiotensin receptor blockers, such as telmisartan, are considered effective in the treatment of hypertension and proteinuria due to chronic kidney disease (CKD) in cats. It selectively blocks the AT1 receptor and does not affect the AT2 receptor, thus effectively blocking the activity of the renin angiotensin aldosterone system. This study aims to compare over time the changes in various indicators, including systemic hypertension and proteinuria, before and after the administration of telmisartan in cats with CKD. Decrease in blood pressure (BP) (p<0.001) and urine protein to creatinine (UP/C) ratio (p<0.001) were found to be statistically significant over time after the administration of telmisartan. BP and the UP/C ratio were 160 ± 22.2 and 0.50 ± 0.647 before telmisartan administration (Day 0), 150 ± 21.0 and 0.27 ± 0.487 on the 30th day (Day 30), 150 ± 17.0 and 0.25 ± 0.376 on the 60th day (Day 60), and 140 ± 17.8 and 0.15 ± 0.233 on the 90th day (Day 90) after administration, respectively. BP and UP/C were statistically significantly lower in cats with CKD over time at each time point from Day 0 to Day 90 at 30 day intervals. Especially after 90 days of telmisartan administration, the improvement of BP and UP/C were estimated to be about 20 mmHg and 0.35, respectively. In conclusion, the oral administration of telmisartan to cats with CKD is effective in improving BP and proteinuria, which has a positive effect on long-term survival in cats with CKD.