Serious severity

Hypertension (High Blood Pressure)

Persistently high blood pressure — a 'silent' condition of older cats that often goes unnoticed until it damages the eyes, brain, heart or kidneys.

⚠️ Common symptoms

Often none until organ damage occursSudden blindness or dilated, unresponsive pupilsBlood visible inside the eyeDisorientation, circling, wobbliness or seizuresIncreased thirst and urination (often from underlying kidney disease)Nosebleeds

High blood pressure is common in older cats and dangerous precisely because it gives so little warning. Blood pressure is the force exerted by circulating blood against the artery walls; when it stays abnormally high, the delicate vessels of certain 'target organs' — the eyes, brain, kidneys and heart — bear the brunt of the damage. Cats are generally considered hypertensive when readings climb above roughly 160–180 mmHg, comfortably above the normal feline range.

The cruel feature of feline hypertension is that the first sign an owner notices is often a catastrophe rather than a warning. The retina at the back of the eye is exquisitely sensitive to high pressure, and many cats are first diagnosed only when they suddenly go blind — the retina having detached or bled — or when an owner notices their cat's pupils are permanently wide and unresponsive. Damage to the brain's blood vessels can cause disorientation, behavioural change, wobbliness or seizures; over time the heart muscle thickens and the kidneys deteriorate further. Much of this harm is irreversible once it has happened.

The great majority of cases are secondary to another illness, above all chronic kidney disease and hyperthyroidism, both of which are themselves common in elderly cats — which is why a cat diagnosed with either should always have its blood pressure checked, and vice versa. The encouraging news is that hypertension is straightforward to detect and to treat. A painless cuff measurement, ideally repeated to allow for the 'white-coat' effect of a nervous cat at the vet, confirms the diagnosis; a daily amlodipine tablet, combined with management of the underlying disease, controls it in most cats. The real key is screening: measuring the blood pressure of senior cats routinely, so the condition is caught and treated before it ever has the chance to steal a cat's sight.

🔍 Causes

Most feline hypertension is 'secondary' — a consequence of another disease rather than a problem in its own right. Chronic kidney disease is by far the commonest association, present in a large majority of hypertensive cats, followed by hyperthyroidism (an overactive thyroid). Less commonly, heart disease, diabetes or certain hormonal tumours raise blood pressure. A smaller group of cats have 'idiopathic' hypertension with no identifiable underlying cause. Because the triggers cluster in older cats, age itself is the biggest risk factor.

🛡 Prevention

Hypertension cannot really be prevented, but its devastating consequences — particularly irreversible blindness — very often can be, simply by catching it early. The single most useful step is routine blood-pressure screening of senior cats: international guidelines suggest checking healthy cats yearly from around seven years of age, and more often in any cat with kidney disease, an overactive thyroid or other risk factors. A blood-pressure measurement is quick, painless and done in the consult room with an inflatable cuff, much as in people.

💊 Treatment

High blood pressure in cats is very manageable once identified. The first-line medication is amlodipine, a calcium-channel blocker given as a small once-daily tablet, which lowers pressure effectively in most cats. Just as important is treating any underlying condition driving the hypertension — most often chronic kidney disease or hyperthyroidism. Cats are then monitored with repeat blood-pressure checks to fine-tune the dose. Where sudden blindness has occurred, prompt treatment occasionally restores some vision if caught very early.

When to see a vet: Because hypertension is silent, the most important time to act is before any signs appear — by including blood-pressure checks in your senior cat's regular health screening. Seek urgent veterinary attention if your cat suddenly becomes blind, develops a fixed, widely dilated pupil, shows blood within the eye, or has unexplained disorientation, circling or seizures, as these can signal a hypertensive crisis. Any older cat drinking and urinating more than usual should also be assessed, since the kidney disease behind it frequently brings high blood pressure with it.

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⚕️ Medical disclaimer

  • This information is educational only and is not a substitute for veterinary advice.
  • Symptoms overlap between conditions — only a vet can diagnose accurately.
  • Never withhold treatment or self-medicate based on information found online.
  • When in doubt, call your vet. Early intervention almost always leads to better outcomes.

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