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Systemic Hypertension

Key Points

• Systemic hypertension is said to be present when a cat has a systolic arterial blood pressure that is repeatedly 180 mm Hg or
greater, under conditions such as quiet surroundings and presence of the owner that aim to minimize environmental influences
(reduction of “white coat effect”), when target organ damage is identified, or both.
• The white coat effect, and technical considerations when measuring blood pressure, are very common causes of misdiagnosis
of systemic hypertension in cats. An optimal environment and exact techniques must be used for obtaining accurate blood
pressure measurements. Otherwise, the white coat effect alone can cause alterations of −27 to +75 mm Hg in the systolic
blood pressure of cats.
• Virtually all cases of systemic hypertension in cats are secondary to an underlying cause; the two most common are chronic
kidney disease and hyperthyroidism. Essential hypertension is rare and constitutes a diagnosis of exclusion.
• Physical manifestations of systemic hypertension include such ocular changes as hyphema or retinal detachment, neurologic
signs such as seizures, cardiac changes including left ventricular concentric hypertrophy, and perpetuation of chronic renal
injury.
• Treatment of systemic hypertension fundamentally involves treating the inciting disorder. Adequate treatment of the cause
may partially or entirely eliminate systemic hypertension.
• Patients with systemic hypertension that require antihypertensive treatment in addition to treatment of the inciting disorder
should be treated with the aim of lowering the blood pressure to a level that is less likely to cause target organ damage,
rather than the aim of fully normalizing the blood pressure.
• With correct treatment both of the underlying disorder and, as needed, of systemic hypertension proper, the desired outcome
is maintenance of status quo in patients without apparent target organ damage and partial or complete clinical resolution of
clinical signs in cats with overt hypertensive lesions.

INTRODUCTION encompasses many normal cats as well as those with
mild or moderate systemic hypertension. In such cases,
Systemic hypertension is a sustained increase in systemic the presence or absence of lesions caused by systemic
arterial blood pressure (BP) (Brown et al. 2007). In the hypertension (“target organ damage”) and repeated
clinical setting, systemic hypertension is considered to measurements, are used for distinguishing between
be present when a cat’s systolic BP is repeatably normal and hypertensive patients (Figure 21.1).
180 mm Hg or greater, under conditions such as quiet The concern with systemic hypertension is target
surroundings and presence of the owner that aim to organ damage. Such damage can manifest acutely, as in
minimize environmental influences (reduction of “white cases of intracranial or intraocular lesions (Figures
coat effect”), when target organ damage is identified, or 21.2–21.8), or chronically and without immediate
both (Brown et al. 2007). A level of uncertainty exists signs, as in cases of hypertensive nephropathy or left
when a cat’s systolic BP is between 150 and 180 mm Hg ventricular hypertrophy. The approach to a patient
under such ambient conditions, because this range with suspected systemic hypertension therefore involves

Feline Cardiology, First Edition. Etienne Côté, Kristin A. MacDonald, Kathryn M. Meurs, Meg M. Sleeper.
© 2011 John Wiley & Sons, Inc. Published 2011 by John Wiley & Sons, Inc.

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