ALISON LAURIE-CHALMERS: Hypertension can cause cats serious harm if left untreated, says Vet Speak correspondent
Register for free to read more of the latest local news. It's easy and will only take a moment.
Chloe was a beautiful, 12-year-old, Tortoiseshell cat. She had been recently diagnosed with early kidney disease, and her advised checks also revealed that her blood pressure was elevated. Chloe was showing signs of a secondary hypertension.
Hypertension is the medical term for high blood pressure. A cat is generally thought to be hypertensive when its systolic blood pressure is above 160 mmHg. In humans, hypertension is related to several factors, including a stressful lifestyle. Although not all causes of feline hypertension have been identified, stress does not appear to play a role in the development of this disorder in cats. In cats hypertension usually occurs because of another concurrent, underlying disease. For example, cats suffering from underlying kidney disease, heart disease or hyperthyroidism, often have some degree of hypertension as well. It is also more common in older cats, especially those overweight. Hypertension can be extremely damaging. The effects are most serious in certain vulnerable organs, such as the eyes, kidneys, heart and brain.
Signs include changes inside the eye, including dilated pupils and intraocular bleeding, sudden onset blindness, disorientation or seizures.
Sudden onset blindness develops because high blood pressure in the eye can cause the eye retina to detach, and cause bleeding within the eye. The affected cat may be seen “searching” and bumping into objects. If the retinae remain detached for more than a day or two, the prognosis is extremely poor for any return of normal vision and if left untreated these signs are permanent, so it is extremely important to seek veterinary advice as soon as possible if you are concerned. If there is any bleeding in the delicate brain tissues this can cause neurological signs such as odd behaviour, a wobbly or drunken gait, seizures and coma.
If the hypertension is caused by another underlying condition the presenting signs will then relate to that disease. For example, in the case of hyperthyroid cats, weight loss, despite a voracious appetite, restlessness and hyperactivity may be the major clinical signs. With an underlying heart disease affected cats may show signs of breathlessness and lethargy. With Kidney disease, inappetence, weight loss, drinking more and urinating more are noted.
A thorough clinical examination can identify the symptoms and signs of hypertension. Your cat’s blood pressure can be measured using a monitoring cuff device applied gently to their leg or tail. Repeated measurements are normally taken over one measuring session, so a longer appointment or a short stay in at the clinic may be necessary to settle the cat down to allow accurate recordings. It is also important to check for the other diseases associated with hypertension, so blood and urine tests may be advised and necessary too.
If your cat does have an underlying health condition, then this must also be treated. However, due to the potentially severe consequences of high blood pressure, it may be necessary to start medication for hypertension immediately. Sixty per cent of cats with chronic kidney disease, and 25 per cent of cats with hyperthyroidism have hypertension. So, the underlying diseases that cause hypertension to develop must also be treated and managed. Long-term success depends on whether this is possible and is dependent on the nature and severity of the underlying disease. In some cases, such as with hyperthyroidism, if the underlying Hyperthyroid disease is successfully treated, then the accompanying hypertension may resolve itself. However, for other underlying conditions, such as chronic kidney disease or heart disease, long-term treatment is often needed for both these diseases and for the hypertension.
Early detection of hypertension is extremely important to minimise the severe and often permanent damaging effects of persistently high blood pressure on the eyes and on other organs. To detect hypertension early, regular blood pressure health checks are recommended in older cats over nine years of age.
The most common treatment for hypertension is oral drugs and there are several treatments now available. It is important that your cat’s blood pressure is regularly monitored to allow any necessary adjustments to medication and to detect for any progression of the condition. Medication may be needed for life and other medication and diet changes may be advised.There is a great degree of individual variation in response to anti-hypertensive drug therapy. In cases of secondary hypertension, the long-term outlook is very much dependent on the nature and severity of the underlying disease that has caused it.
Many cats can go on to lead comfortable lives following a diagnosis and stabilisation of hypertension. But if left untreated the secondary signs of hypertension, such as blindness, may be irreversible. Chloe was given medication to reduce her hypertension, along with her ongoing kidney medication. She seemed to be much happier and more relaxed.
If you are concerned that your cat may be showing some symptoms, or if they have ongoing kidney, heart, or thyroid disease, call your vet for an appointment.
• Alison Laurie-Chalmers is a senior consultant at Crown Vets in Inverness.
