You might have heard of hypertension as it is a common problem in humans. Hypertension is high arterial blood pressure. It is also a common condition seen in cats, particularly older cats. Some cases of hypertension occur without any other underlying problem; however, this is much more unusual. In most cases hypertension will be a secondary complication of another disease. The most common scenario is hypertension seen secondary to chronic kidney disease or hyperthyroidism. Other risk factors are heart disease, obesity or diabetes. Occasionally a tumour of the adrenal gland can also cause hypertension.

High blood pressure is damaging to the body. If blood pressure remains raised there can be damage to sensitive organs and tissues. 

What are the effects of hypertension?

Hypertension can affect vulnerable parts of your cat’s body;

Eyes

Hypertension may cause bleeding into the eye as well as damage the retina such as swelling and detachment. This can lead to vision problems which can be permanent. 

Kidneys: 

Sustained high blood pressure can damage the kidneys; this can increase the risk of kidney failure. However sometimes high blood pressure is the result of diseased kidneys, and once the blood pressure rises, the kidney disease worsens. 

Brain: 

Occasionally hypertension might cause bleeds in the brain or elsewhere in the nervous system, e.g. the spine. 

Heart: 

The heart must work harder in a cat with hypertension, the heart muscle becomes thickened and can progress to heart failure. 

What are the symptoms seen with hypertension?

  • Vision problems, such as bumping into things. This is often the first sign that you might notice if your cat has high blood pressure. 
  • Odd behaviour, seizures and being wobbly are some of the many signs which might occur if there has been a bleed in the nervous system or brain. 
  • Breathlessness or lethargy if hypertension leads to heart failure.
  • Signs related to kidney disease such as drinking more or vomiting.

How is hypertension diagnosed?

Hypertension is diagnosed by measuring blood pressure using a device which can detect blood flow through arteries. A small inflatable cuff will be placed around the cat’s limb or tail. Often several measurements need to be taken, as cats will sometimes be anxious during the process and this can give a falsely high reading. Human blood pressure machines are not appropriate to use with cats, so only specialist devices will be used by your vet. 

High blood pressure should be suspected in any cat with heart disease, hyperthyroidism or chronic kidney disease. Your vet may suggest screening an older cat for hypertension during routine check-ups. This is because sometimes the first sign of a problem is sudden vision loss, and this cannot always be reversed. Symptoms can develop very suddenly when organ damage becomes more serious. Often you will be unaware of the problem until late on. Screening and catching hypertension in the earlier stages of the disease process will give your vet the opportunity to start treatment early.

What is the treatment for hypertension?

Finding and treating any underlying disease such as hyperthyroidism will be the first step. Sometimes this alone is enough to reduce the blood pressure back to the normal range. If the underlying disease is being treated but hypertension remains, then medication may be needed. Medication is also used in the case of primary hypertension. Treatment primarily focuses on reducing the blood pressure using medications known as antihypertensives. 

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What is the outlook for my cat?

In cases of primary hypertension (where no underlying disease exists) the prognosis is fair. It is usually possible to control the hypertension with medication. Regular check ups will be needed to monitor your cat to avoid any complications.

In secondary hypertension the outlook very much depends on the underlying cause. Some disease processes will be easier to control or cure than others. For example, a hyperthyroid cat may have a better prognosis than a cat with end stage kidney disease. Your vet will be able to give more information about how hypertension will affect your cat’s life.

In cats presenting with sudden vision loss it is vital urgent veterinary care is sought. This is a medical emergency and unless the blood pressure is rapidly brought back into the normal range the damage to the eyes may be irreversible.

If you are noticing any signs of symptoms which concern you it is always best to arrange a check-up for your cat with your vet. 

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