High blood pressure in cats
High blood pressure is not something you immidiately associate with cats, so it is a bit of a shock when the vet diagnosis it and takes it very seriously. This is because high blood pressure in cats (hypertension) is rarely a primary condition in cats. It is rather the result of underlying condition, the most common being chronic kidney failure or hyperthyroidism. This is often referred to as secondary hypertension. There are other causes of high blood pressure in cats including obesity and Cushing's disease - a tumour in the pituitary or adrenal gland which causes excessive production of corticosteroids. Hypertension can have a very serious consequences including blindness, neurological disorders or even congestive heart failure.
Conditions associated with hypertension:
- Bleeding into the eye from burst blood vessel may result in detachment of the retina and swelling which often leads to the permanent blindness in cats.
- Heart failure. When the blood pressure is too high, the heart has to work doubly hard to pump the blood. Overtime that may cause thickening of the walls of the heart chambers which when untreated can lead to the congestive heart failure.
- High blood pressure is also a contributing factor to kidney damage and may in the case of renal failure, make the condition much worse.
One of the major problems in early diagnosis of hypertension in cats is luck of obvious symptoms. As a result, very often the first thing which the owner notices is a sudden onset of blindness due to bleeding into the eye and damage to the retina. Unfortunately, at this stage it is often too late to save the cat's eyesight. Because the high blood pressure is often a secondary condition, any potential signs of hypertension such as breathlessness or lethargy are likely to me masked by symptoms of primary condition.
And yet the diagnosis of high blood pressure is very simple, actually as simple as in humans since The equipment used is often similar to that used routinely in people, with an inflatable cuff placed around one of the front legs or the tail. Measuring blood pressure only takes a few minutes, is completely pain-free and is extremely well tolerated by most cats. So the diagnosis can be made within minutes. It is now recommended that blood pressure should me measured in older cats as part of the routine veterinary examination. This would serve two main function, prevention of serious complication arising from the hypertension, but also perhaps an early signs of an underlying condition which causes the high blood pressure.
Management of hypertension involves administration of drugs which lower the blood pressure. Although, in human there are a number of agents which are very successful in controlling blood pressure, a good anti-hypertensive drug is still largely lacking. Although a number of agents are available for treatment of hypertension these are not specifically licensed for this use in cats. Examples of drugs commonly used are amlodipine (trade name Istin) which is a calcium channel blocker and benazepril (trade name Fortekor) - an ACE inhibitor. In general amlodipine is more effective in cats although in some cats a combination of both of these drugs may be necessary for adequate control of the blood pressure.
Cat with primary hypertension can be managed successfully with anti-hypertensive drugs and as long as there is no permanent health imperment before the diagnosis of high blood pressure, there is no reason for the cat to lead a long and normal life. With secondary hypertension, the prognosis very much depend upon the primary illness, its nature and severity. So for example, if the hypertension is caused by hyperthyroidism, the condition is treatable and following successful treatment of hyperthyroidism, the cat's blood pressure should stabilised as well. In the case of high blood pressure caused by chronic renal failure, the prognosis are considerably poorer. However, in all cases it is important to control the blood pressure since the reduction of blood pressure will be beneficial. For example, in humans it is well recognised that lowering blood pressure slows down the degeneration of kidney, and it becomes more and more apparent that the same may be true for cats.