High blood pressure is a common problem for humans but did you know that cats can get it too? High blood pressure, also known as hypertension, is actually quite common in older cats, especially those with other diseases such as kidney disease or hyperthyroidism. The symptoms can be quite subtle or mimic those of other diseases so many cases remain undetected for quite some time. If left untreated, however, hypertension can lead to significant secondary health problems, so it’s definitely worth testing for.

Bob having his blood pressure checked.
Bob having his blood pressure checked.

What exactly is high blood pressure?

High blood pressure occurs when the pressure within the blood vessels exceeds a certain threshold. Think of the hosepipe used to water your garden. If you turn the tap on too strongly, the water shoots out of the nozzle uncontrollably, damaging your flowers. The same is true for the body – organs like the brain and kidneys need blood to survive but if the blood pressure gets too high, it can start to damage the very organs it is trying to keep alive. To further complicate things, blood vessels have a tendency to leak under pressure and this extra fluid can cause further problems.

How do cats develop high blood pressure?

Many things can cause hypertension in cats from certain medications to neurological disease, but the two most common causes are kidney failure and hyperthyroidism. Both of these illnesses cause alterations in the very precise mechanisms that monitor and control blood pressure. It doesn’t always correlate with the severity of the disease (i.e., severe hypertension can be seen with only mild kidney disease) and in the case of hyperthyroidism, we sometimes see hypertension develop only after the thyroid problem has been treated.

What are the symptoms of hypertension?

The clinical signs associated with high blood pressure depend on which organs are most badly affected. One of the most common signs is acute blindness because the high pressure within the vessels of the eye causes the retina to detach from the nerves that tell the brain what the eye is seeing. So you may notice the cat bumping into things (although it’s amazing how many owners aren’t aware of their cat’s blindness because cats are so good at using their other senses to compensate), staying closer to home or having very dilated pupils or ‘wide eyes’. Another organ that is commonly affected is the brain so you might see serious signs such as circling and seizures or perhaps much more subtle behavioural changes such as crying out at night or being less sociable when people are around (how else would you tell if your cat had a headache?). You may see bleeding in unexpected places like nosebleeds or blood in the urine. It can also speed up the progression of kidney failure. The list goes on so any unexplained physical or behavioural change warrants a blood pressure check, especially in older cats.

How is high blood pressure diagnosed?

The only way to tell if a cat has high blood pressure is to measure it. The process is much the same as it is in humans – a cuff is inflated around the arm or leg (or possibly the tail) which controls blood flow to the limb. A special device (sometimes a handheld Doppler unit or sometimes an automatic sensor) then measures the blood pressure. It doesn’t hurt and isn’t usually a stressful process that is good because if the cat is stressed the reading can be artificially elevated. Sometimes the cat objects to the cuff being tightened so it can help to practice a few times before taking the reading. Some cats just plain hate going to the vet or any kind of restraint whatsoever so it isn’t always possible to get a reading, although many clinics have special protocols in place to help the cat stay as calm as possible before attempting to take a blood pressure. If all else fails in the clinic, a reading might be possible at home where they are more comfortable.

Is there any treatment?

Absolutely. There are several medications that can treat high blood pressure but the one that most vets use these days is called amlodipine. A very tiny dose goes a long way, and it’s important that once you start the medication, you give it regularly to avoid dangerous spikes in blood pressure. Once a cat starts the medication (usually a tiny tablet that most cats seem to tolerate relatively well) it’s important to follow up with regular blood pressure checks to ensure that they are on the correct dose.

I’ve seen many cats respond very well indeed to treatment and many owners report that their cat seems years younger once their blood pressure is under control, even if they hadn’t noticed any symptoms in the first place. It is yet another example of how well cats can hide their illnesses and how important it is for owners and vets to work together to detect health problems while there is still time to treat them effectively.

If you think your cat is showing signs of high blood pressure or if you have an older cat with unexplained physical or behavioural changes, please speak with your vet about having their blood pressure checked. You may never know unless you make an effort to look for it.

Amy Bergs DVM MRCVS  – Visit The Cat Doctor website by clicking HERE