Changes in Systolic Blood Pressure over Time in Healthy Cats and Cats with Chronic Kidney Disease

Background: Hypertension is a common problem in older cats, most often associated with chronic kidney disease (CKD). Cross-sectional studies have suggested that blood pressure in cats increases with age. Hypothesis/Objectives: To determine whether blood pressure in cats increases with age and whether this occurs independently of the presence of CKD. To investigate risk factors for developing hypertension. Animals/Subjects: Two hundred and sixty-five cats with CKD and 133 healthy cats >= 9 years were retrospectively identified. Methods: Four groups were created according to status at initial evaluation (CKD or healthy) and blood pressure at the last included visit (normotensive [NT] or developed hypertension [DH]): Healthy-NT, Healthy-DH, CKD-NT and CKD-DH. Systolic blood pressure (SBP) over time slopes were compared with 0 and between groups. Risk factors for the development of hypertension were investigated, and associations of biochemical and clinical variables with SBP were examined. Results: Cats that were hypertensive at CKD diagnosis (n = 105) were not included in further analyses. Twenty-seven cats with CKD and 9 healthy cats developed hypertension >= 3 months after diagnosis of CKD or their first visit. Systolic blood pressure significantly increased with age in all cats (P <.001). Healthy cats were at less risk than cats with CKD to become hypertensive (hazard ratio 0.2, P <.001), with creatinine being an independent risk factor for the development of hypertension. Conclusions and Clinical Importance: The high prevalence of hypertension in azotemic cats in this study shows the importance of monitoring of SBP in elderly cats, and in particular in cats with CKD.