One common problem of older cats is hypertension, more commonly associated with chronic kidney disease (CKD). Serum creatinine levels are elevated in almost 75% of cats with high blood pressure. On the other side, 19 to 65% of cats with chronic kidney disease are hypertensive. Chronic kidney disease prevalence increases with age in humans, the same is also true for cats. In most human populations, the mean systolic blood pressure (SBP) increases with age along with the prevalence of hypertension. This study hypothesizes that blood pressure increases with age in senior cats plus that the rate of this increase is even greater in cats with CKD.
In this study, cats were diagnosed with systemic hypertension when they had an SBP ≥ 170 mm Hg on 2 consecutive visits or a SBP ≥ 160 mm Hg with concurrent evidence of hypertensive retinopathy or choroidopathy. Cats with CKD and also were hypertensive at the time of this diagnosis were not included in the study. The included cases were placed into 4 groups according to their status at the initial visit (CKD or healthy) and blood pressure at the last study visit (normotensive [NT] or developed hypertension [DH] ≥ 3 mos after CKD diagnosis or first visit). Two hundred and sixty-five cats with CKD and 133 healthy cats 9 years of age and older were identified.
Of the cats that developed hypertension ≥ 3 mos after diagnosis with CKD or their first visit, 27 had CKD and 9 were healthy cats. Healthy cats were at lower risk than cats with CKD to develop high blood pressure. Creatinine was an independent risk factor for the development of hypertension.
The authors concluded that both healthy cats and cats with CKD can show a significant increase in SBP with increasing age, comparable to the human situation. No developed recommendations exist for the best screening intervals for senior cats with normal blood pressure. Based on this study’s results, more frequent blood pressure measurements should be encouraged if a cat is presented with a mean SBP of ≥ 140 mm Hg. Cats with CKD have a significantly higher probability of becoming hypertensive, so the screening intervals between visits could be shorter. A shorter screening interval could lead to earlier diagnosis and decreased development of target organ damage.
- Blood pressure increases with age in all cats.
- Cats that develop clinically significant hypertension have a higher blood pressure at their initial visit than cats with normal BP.
- Cats with CKD are more likely to develop hypertension.
- It is important to monitor SBP in elderly cats, especially those with CKD.
- Cats with a higher baseline blood pressure at diagnosis of CKD should be more closely monitored than cats with a lower baseline BP.
- Early diagnosis of CKD is essential so appropriate management can be offered.
- Regular, routine examinations are important for all cats and especially elderly cats. (VT)
Huhtinen M, Derre G, et al. Randomized placebo-controlled clinical trial of a chewable formulation of amlodipine for the treatment of hypertension in client-owned cats. J Vet Intern Med. 2015 Apr 9.