When a cat is diagnosed with chronic kidney disease (CKD), most of the attention goes to blood work, food and fluids. Blood pressure can get lost in the shuffle. Yet high blood pressure is common in kidney cats, and it usually causes no obvious signs until it has already done some harm.
The reassuring part: it is easy to check, it is treatable, and regular measurements are one of the most practical ways to protect your cat. This guide explains what you need to know.
Why kidney cats get high blood pressure
The kidneys help control blood pressure. They manage how much salt and water the body keeps, and they release hormones that tighten or relax blood vessels. When the kidneys are diseased, that balance can tip toward pressure that is too high. Vets call this systemic hypertension.
The link runs both ways. CKD can cause high blood pressure, and high blood pressure can put further strain on the kidneys. That is part of why IRIS (the International Renal Interest Society) includes blood pressure in how vets describe a cat's kidney disease, alongside creatinine, SDMA and urine protein.
Hyperthyroidism, which is also common in older cats, can raise blood pressure too. Many senior cats have both conditions, so your vet may check thyroid levels as well.
Why it matters: target organs
Vets talk about target organs — the parts of the body most likely to be harmed by high blood pressure over time.
- Eyes. The small blood vessels at the back of the eye are delicate. High pressure can cause bleeding or detachment of the retina. This can lead to sudden blindness. Sometimes the first sign owners notice is dilated pupils or a cat who seems lost.
- Heart. The heart has to work harder to pump against high pressure, and its muscle can thicken. Your vet may hear a murmur or an irregular rhythm.
- Brain. High pressure can affect the brain. Signs can include confusion, wobbliness, unusual vocalising at night, a head tilt, or in severe cases seizures.
- Kidneys. High pressure can speed up kidney damage. It is often linked with protein leaking into the urine, which your vet measures with a UPC test.
None of this is meant to frighten you. It is the reason regular checks are worthwhile. Catching high blood pressure early means it can be managed before these organs are affected.
How blood pressure is measured in cats
Measuring a cat's blood pressure is much like measuring a person's. A small cuff goes around a front leg or the tail. Most clinics use a Doppler device, which lets the team hear the blood flow as a soft whooshing sound. Some use an oscillometric machine that reads the pressure automatically. It does not hurt. Many cats sit quietly in a carrier bottom or on a towel while it is done.
To get a reliable reading, good clinics follow a few steps:
- Letting your cat settle in a quiet room for several minutes first, ideally with you there.
- Using the same cuff position and the same method each visit when possible.
- Taking several readings in a row and using the average, after discarding the first one.
- Writing down the cuff size and site so the next check can match.
The white-coat effect
Cats can get stressed at the vet, and stress raises blood pressure. Vets call this the white-coat effect. A single high reading in a nervous cat does not always mean true hypertension. If the reading is high but your cat has no signs of organ damage, your vet may want to recheck on another day before starting treatment. Cat Friendly handling — quiet rooms, gentle restraint, time to calm down — helps get a truer number. The AAFP's Cat Friendly Practice program focuses on exactly this kind of approach.
What the numbers mean
Vets usually describe the systolic pressure — the top number — in millimetres of mercury (mmHg). IRIS groups cats into four categories based on systolic pressure:
- Under 140 mmHg — normotensive. Minimal risk of target-organ damage.
- 140–159 mmHg — prehypertensive. Low risk.
- 160–179 mmHg — hypertensive. Moderate risk.
- 180 mmHg or higher — severely hypertensive. High risk.
These categories describe risk. They do not, on their own, decide treatment. Your vet will consider repeated readings, how calm your cat was, whether there are signs of damage to the eyes or other organs, and other lab results. You can read more about how blood pressure fits into kidney disease on our IRIS stages page.
How high blood pressure is treated
Treatment is always directed by your vet. They will choose a medicine, set the amount, and plan rechecks. Never adjust or stop blood pressure medicine on your own, and never give your cat a human blood pressure tablet.
Two medicines vets commonly use for cats are:
- Amlodipine, which relaxes blood vessels. It is widely used as a first choice for cats with hypertension.
- Telmisartan, which works on hormone pathways that control blood pressure and is also used to reduce protein in the urine.
Some cats need one, some need both, and some need other medicines. Your vet may also review sodium in your cat's diet, though very low-salt diets on their own are not usually enough to control pressure.
After starting treatment, vets typically recheck blood pressure within a couple of weeks or so, then at regular intervals once things are stable. They may also recheck kidney values and urine protein. Ask your vet what schedule they recommend for your cat.
Making checks easier for your cat
Because stress can push readings up, small changes can make a real difference:
- Practise with the carrier at home. Leave it out with a soft blanket and treats so it is not only linked to vet visits.
- Cover the carrier with a towel in the car and waiting room.
- Ask for a quiet room or to wait in the car until the room is ready.
- Bring a familiar blanket that smells of home.
- Book a time when the clinic is calmer, if possible.
- Ask about pre-visit calming options if your cat is very anxious. Your vet can advise whether this is suitable.
Write down each reading your vet gives you. Over months, a simple record shows your vet the pattern, not just one moment. Our printable logs have space for notes, and a notes app or calendar works too. If you want to make sense of your cat's latest blood work too, try the Lab Decoder.
Signs to mention at your next visit
High blood pressure is often silent, so regular checks matter more than watching for symptoms. Still, mention any of these to your vet:
- Pupils that look large, or eyes that look different from each other.
- Bumping into things, especially in dim light.
- Blood visible inside the eye.
- New confusion, pacing, or crying at night.
- Wobbliness or a head tilt.
- Faster breathing at rest.
Sudden blindness, seizures, or collapse need a vet straight away.
The bottom line
High blood pressure is common in cats with kidney disease, and it often hides until it causes damage. Regular, calm measurements are the best protection. If your cat needs treatment, it is usually simple — often a small daily medicine — and your vet will guide every step.
Ask for a blood pressure check at each kidney visit. It is one of the kindest, simplest things you can do for your cat.
Sources & further reading
- International Renal Interest Society (IRIS) — Blood pressure substaging of CKD
- International Society of Feline Medicine (ISFM) / International Cat Care — Consensus guidance on feline hypertension
- American Association of Feline Practitioners (AAFP) — Cat Friendly handling and senior care guidance
- Cornell Feline Health Center — Hypertension and kidney disease in cats
KidneyPaw provides general information to help you care for your cat alongside your veterinarian. It is not veterinary advice and does not diagnose, stage or treat. If you are worried about your cat, call your vet.