Secondary hypertension and its treatment in cats

There are three types of hypertension, or high blood pressure, in cats: primary (idiopathic), secondary and situational (previously referred to as ‘white coat’ hypertension). Secondary hypertension, which develops in association with an underlying disease process or because of a medication or toxin, is the most common type of hypertension in cats (Taylor et al, 2017; Acierno et al, 2018). The conditions typically associated with hypertension occur with increasing prevalence in older cats; therefore, the prevalence of secondary hypertension also increases with advancing age (Bijsmans et al, 2015; Conroy et al, 2018). The most common cause of hypertension in cats is chronic kidney disease (Maggio et al, 2000; Elliott et al, 2001; Sansom et al, 2004; Conroy et al, 2018). Other conditions associated with high rates of hypertension include hyperthyroidism (Elliott et al, 2001; Conroy et al, 2018), acute kidney injury (Cole et al, 2017) and hyperaldosteronism (although this condition is uncommon). Pheochromocytoma and Cushing's syndrome (Henry et al, 1993; Valentin et al, 2014) can also cause hypertension, but both are rare in this species. Cats with diabetes mellitus can be documented to have concurrent hypertension, but it is not clear that it occurs with a higher frequency than in the general cat population (Al-Ghazlat et al, 2011). Documentation of any of these conditions should prompt blood pressure measurement; details on performing these measurements and when to do so are covered elsewhere (Caney, 2021).