Hypertension, or high blood pressure, is a fairly common but potentially severe problem for older cats. Over the past few years the importance of monitoring blood pressure in older cats has been recognised and monitoring equipment is now readily available in most veterinary practices.
What is Blood Pressure and Hypertension?
The blood pressure is the force that is exerted by the blood against the walls of blood vessels. A certain amount of pressure is needed to enable the heart to effectively pump blood around the body in order to deliver oxygen and energy to the various organs, muscles and tissues. When an animal (or person) becomes hypertensive, the blood is pumped with greater force than normal which puts extra strain on the vessels, arteries and heart.
What Causes Hypertension?
Hypertension in cats may be caused by (or be a side effect of) another disease, illness or problem such as Kidney disease, Heart Disease, Hyperthyroidism, Diabetes and Obesity. However, many older cats can develop hypertension without having other illnesses or disease, or even showing any other clinical signs. Sadly if it is not detected early on and is left untreated, it can cause serious and sometimes sudden consequences, including the following illnesses and symptoms
- Kidney problems
- Heart problems
- Neurological (Brain) problems such as seizures or disorientation
- Weight loss
- Poor appetite
- Increased thirst
- Increased urination
- Dilated pupils (large pupils that do not get smaller in the light)
- Blood spots/bleeding in the eyes
- Respiratory problems
How is blood pressure measured?
Blood pressure is measured in cats using the same method that is used for humans.
In humans, two values are taken into account, the higher one being the blood pressure in the arteries that is recorded when the heart beats (systolic pressure) and the lower value, when the heart rests between beats (diastolic pressure). These two values are recorded one above the other, separated by a slash mark; Normal human blood pressure is around 120/70-80 mmHg (which stands for millimetres of mercury). With cats, we tend just focus on the systolic blood pressure reading which is typically higher than humans, at around 120 to 170 mmHg.
How Is Hypertension Diagnosed?
The vet will make a diagnosis by using the Sphygmomanometer as mentioned below, but also by taking into account any other clinical symptoms that your cat may have.
Because hypertension is often associated with other conditions such as kidney disease and hyperthyroidism blood pressure may be tested for if these illnesses are present or, if hypertension is the initial problem, blood tests may be performed to check for these other illnesses.
Sometimes the vet may need to take 2 or 3 readings over 2 to 3 weeks to confirm a diagnosis of hypertension. Factors such as the cat being anxious, distressed or even excited can give ‘false high’ pressure readings which is why your vet may recommend several measurements over the course of a few weeks.
How Is Blood Pressure Recorded?
Monitoring the blood pressure in cats is a non-invasive and relatively straightforward procedure that can be carried out by a vet or veterinary nurse at the practice (as long as the cat is cooperative and happy to sit still for a while!). The procedure is very similar to human blood pressure testing and is measured with an instrument called a sphygmomanometer.
- A small cuff attached to the sphygmomanometer is wrapped around the cat’s leg (or occasionally the tail).
- A Doppler probe is used to listen for the pulse in the cat’s lower leg, near the main stopper pad. The probe is a handheld diagnostic device that emits ultrasonic waves into the body; it picks up the sound of the blood flow (pulse) and enables the vet or veterinary nurse to hear it.
- The cuff is gently inflated with a pump until the pulse can no longer be detected, then a valve is opened to slowly deflate the cuff.
- The reading on the sphygmomanometer is recorded when the pulse can be heard again as the cuff is deflating.
- The measurements are taken 3-6 times and the vet will use an average of the readings as the blood pressure measurement.
How Is Hypertension Treated?
Medication is available to treat hypertension and fortunately, with appropriate monitoring and treatment, feline hypertension is usually manageable. Early diagnosis means that treatment can be started as soon as possible, which reduces the risk of damage to the body from persistent high blood pressure. Occasionally, if the underlying disease or illness is treated, the hypertension may resolve on its own, but most cats will need to be on medication for life after diagnosis. Many cats may also be on medication for other conditions at the same time.
How Often Should Blood Pressure Be Monitored?
It is recommend that any cat over the age of 8 years old is tested annually to make sure they do not have hypertension. In healthy cats this will be a record of what is normal for them and the offers the possibility of detecting hypertension early on before other signs are present. If the vet has diagnosed hypertension, they may initially recommend monthly monitoring until it is under control. This may then be reduced to a test every 3 months or so.
The aim is to keep cats as calm as possible during the monitoring procedure to avoid the ‘white coat effect’ of blood pressure being raised due to anxiety. Some cats will be better away from their owners and some cats will prefer to stay with their owners.