Systemic hypertension (high blood pressure) is a common finding in feline CRF, and although its true prevalence is difficult to determine, a recent study identified hypertension in around 20% of cats with CRF seen in a first opinion veterinary practice (Syme et al JAVMA 2002, 220: 1799-1804).
Hypertension can have serious consequences including blindness and neurological signs. Blood pressure should therefore be evaluated as a routine part of all check-ups of CRF cats and anti-hypertensive therapy prescribed to those where the average blood pressure readings, taken with the cat in a calm state, are persistently high, or where there is evidence of retinal damage (e.g. bleeding into the eye and/or retinal detachment) caused by high blood pressure.
The most commonly used drugs for treatment of feline hypertension are the calcium channel blocker amlodipine besylate and the ACE inhibitor, Fortekor. In general, amlodipine is more effective in lowering blood pressure than the ACE inhibitors although in some cats, a combination of both of these drugs may be required to achieve adequate control of blood pressure.
In humans, there is unequivocal evidence that control of systemic hypertension slows the progression of chronic renal failure. Such evidence is lacking for dogs and cats but, nevertheless, given our current state of knowledge anti-hypertensive therapy is recommended for any CRF cat with a systolic blood pressure consistently in excess of 170 - 180 mmHg or with evidence of clinical hypertension such as bleeding into the eye.