The evolution of feline hypertension
Hypertension is a common clinical problem in aged cats and most often develops secondary to other diseases, such as chronic kidney disease (CKD) and hyperthyroidism, and is classified as secondary hypertension. In about 20% of cases, however, no specific disease is identified, and the condition is referred to as idiopathic hypertension.1
Regardless of the underlying cause, a key factor in the development of hypertension is the renin-angiotensin aldosterone system (RAAS). Chronic, excessive RAAS activation may lead to the development of systemic hypertension and detrimental effects to the kidneys.
Furthermore, the clinical consequences of hypertension can be severe, and detrimental, particularly for the eyes, heart, brain as well as the kidneys – so called ‘target organ damage’.
The tricky part about hypertension in cats is that its presence is unlikely to be immediately apparent, unless damage to the target organs is detected. Thus, more widespread routine monitoring of feline blood pressure would allow affected animals to be identified earlier and allow institution of approaches to prevent damage to the target organs. It also is important to recognize that blood pressure may increase temporarily as a consequence of excitement or anxiety-related sympathetic activation. This is referred to situational hypertension, though it is often called “white coat hypertension.”
Hypertension occurs commonly in aged cats, most notably those with CKD. In fact, hypertension has been documented to occur in up to 65% of cats with CKD2. Consequently, it is critical for practitioners to monitor blood pressure in their feline patients on a regular basis after they reach 7 years of age. This is particularly true for cats with recognized risk factors, including CKD, hyperthyroidism, hyperadrenocorticism, or evidence of target organ damage.
The morbidity associated with hypertension and CKD can be significantly reduced through the combination of early diagnosis and initiation of appropriate treatments. Most recently, managing feline hypertension specifically through selective blockade of angiotensin AT1 receptors has been clearly demonstrated.
Written by Tanja Zimmering, DVM, DECVIM
1. Elliott J, Fletcher M, Syme HM. Idiopathic feline hypertension:Epidemiologic study [abstract]. J Vet Intern Med 2003; 17:754. 2. Brown S., Atkins C, Bagley R et al. ACVIM Consensus Statement:Guidelines for the Identification, Evaluation, and Management of Systemic Hypertension in Dogs and Cats. J Vet Intern Med 2007; 21:542–558