Blood Pressure Screening in Older Cats

Systemic hypertension in cats is common from around age nine onward and is frequently secondary to chronic kidney disease or hyperthyroidism, yet it produces no obvious signs until the eye or another organ is already damaged. Routine screening catches it before that damage occurs.

Why Hypertension in Cats Is Usually Secondary

Chronic kidney disease and hyperthyroidism both disrupt normal blood pressure regulation, the former through impaired sodium handling and activation of the renin-angiotensin system, and the latter through an increased cardiac output driven by excess thyroid hormone, meaning a cat with either condition should be routinely screened even without other signs.

Sustained high pressure damages small blood vessels throughout the body, but the retina's vessels are particularly vulnerable, and sudden retinal detachment or haemorrhage causing acute blindness is often the first sign owners notice, by which point the hypertension has usually been present for some time.

How Blood Pressure Is Measured in a Conscious Cat

• Sudden blindness or dilated, unresponsive pupils, suggesting retinal detachment
• Increased thirst and urination consistent with underlying kidney disease
• Weight loss with an increased appetite, suggesting concurrent hyperthyroidism
• A new heart murmur or gallop rhythm detected during a routine exam
• Disorientation or unsteady movement, which can reflect a hypertensive event

Because sudden blindness from retinal detachment can be the first visible sign of hypertension, routine screening in cats over nine, and especially those with kidney disease or hyperthyroidism, is aimed at preventing this outcome rather than reacting to it.

The Eye as an Early Warning Organ

Blood pressure is measured non-invasively using Doppler ultrasound or oscillometric devices with an appropriately sized cuff on a limb or tail, taken as an average of multiple readings after the cat has settled to reduce stress-related false elevation.

A single high reading is interpreted cautiously because of situational stress, sometimes called white-coat hypertension; vets typically confirm persistent elevation across separate visits, or assess target organ changes such as retinal lesions, before diagnosing true systemic hypertension.

Target Values and What Counts as High

Treatment addresses both the elevated pressure itself and any underlying disease driving it.

• Start amlodipine as the first-line antihypertensive for most hypertensive cats
• Treat underlying hyperthyroidism or chronic kidney disease concurrently, not separately
• Recheck blood pressure within one to two weeks of starting or adjusting medication
• Perform a retinal exam at diagnosis and at recheck visits to monitor for damage

Managing Hypertension Alongside Its Underlying Cause

Cats with confirmed hypertension typically need blood pressure rechecked every three to six months for life, alongside monitoring of the underlying kidney or thyroid disease, since dose adjustments are common as either condition progresses.

Minimising stress at the time of measurement, such as allowing acclimatisation time in a quiet room before cuffing, improves accuracy and helps avoid unnecessary medication changes based on a stress-inflated reading.

When to seek help urgently

• Sudden onset blindness or dilated pupils not responding to light
• Disorientation, head pressing or seizure-like activity in an older cat
• Acute collapse in a cat with known kidney disease or hyperthyroidism
• A very high blood pressure reading confirmed on repeat measurement at the clinic

Blood pressure screening is now a recommended part of senior cat wellness checks; discuss the appropriate frequency for your cat, particularly if kidney disease or hyperthyroidism is present, with your own veterinarian.