When you go to the doctor, part of your regular checkup is a blood pressure check. Have you ever wondered how your vet checks a cat’s blood pressure?
Pierre had his blood pressure checked, so he’ll be able to demonstrate for us.
Why Check a Cat’s Blood Pressure?
Cats, like humans, can get high blood pressure, especially as they get older. Hypertension in cats can contribute to heart failure. It can also cause sudden blindness when the high blood pressure inside the eye causes the retina to detach.
Catching rising blood pressure early can prevent these health complications.
Measuring Human Blood Pressure
You’re probably familiar with the cuff that a nurse inflates on your arm during a blood pressure exam. When the cuff is pumped up, it temporarily cuts off circulation to your arm. The nurse uses a stethoscope to listen for the heartbeat at your inner elbow, where your brachial artery is close to the surface.
When the cuff starts to slowly deflate, the nurse records the pressure at which the heartbeat begins to be audible through the stethoscope (systolic blood pressure) and the pressure where your heartbeat is no longer audible (the diastolic blood pressure).
Measuring Cat Blood Pressure
The process in cats is similar. The biggest difference is that cats have much smaller blood vessels than we do, so a stethoscope won’t work when listening for a pulse during blood pressure measurement. Instead, vets usually use a doppler ultrasound machine.
A doppler ultrasound machine sends and receives sound waves that bounce off the blood cells inside a blood vessel. Moving blood cells cause the sound to change, so your vet tech can use it to hear a cat’s pulse.
Some vet techs put a specially-pet-sized blood pressure cuff on your cat’s leg, where they can listen to the pulse in the common digital artery. The techs at our vet use the cat’s tail, where they can monitor the coccygeal artery.
Some vet techs will clip a small spot of hair to give better access to the skin where they place the probe from the doppler machine against the skin, but they were able to part and wet Pierre’s short fur with rubbing alcohol instead so they could press the probe in the right spot to hear his pulse.
Then the vet tech inflates the cuff and listens as it deflates several times. There wasn’t really much to see when this is going on, other than Pierre getting increasingly annoyed with something pinching his tail.
A doppler machine doesn’t give a very good diastolic measurement, so instead of two numbers for his blood pressure, Pierre only got one number, the systolic measurement, which was 170. That value is a higher than the normal 80–140 mm Hg, but Pierre gets pretty scared at the vet.
Adjusted for “white coat syndrome,” his blood pressure is still a little high, so we’ll be watching it in the future.
What About Those Automated Testing Machines?
You may have seen automated blood pressure testing devices for humans and wonder why they don’t use those for cats, too. The answer is that they do! These are called oscillometric blood pressure measurement devices, and they use an electronic sensor with a digital readout of the pressure.
These automated devices are not considered by most doctors and veterinarians to be as accurate as the old fashioned way of measuring blood pressure. They are also costly, so your vet is more likely to use the doppler method to check your cat’s blood pressure.
Research and further reading:
Cornell Feline Health Center, Hypertension
American College of Veterinary Internal Medicine, Guidelines for the Identification, Evaluation, and Management of Systemic Hypertension in Dogs and Cats