The International Society of Feline Medicine agree that after a cat reaches the age of seven they should receive routine blood pressure monitoring. This idea is unusual as far as I am aware. However, it is based upon sound evidence.
Studies by a company, Ceva Animal Health, show that hypertension (high blood pressure) effects one in eight cats over nine years of age. The risk increases if the cat suffers from other conditions such as chronic kidney disease (which is commonplace in older cats) when one in three cats suffer from hypertension. One in four cats with an overactive thyroid are also estimated to suffer from hypertension.
Hypertension can cause damage to the body organs such as the brain, heart, kidneys and eyes. There are no clear symptoms and it can develop silently, under the radar. Suddenly the consequences of hypertension appear.
Further Notes on Hypertension
It is usually a secondary problem and chronic renal failure is the most common cause. Studies indicate that from 20 to 61% of cats with renal failure also suffer from hypertension. I remember my cat had chronic renal failure but was never checked for hypertension.
About 87% of cats with an overactive thyroid (hypothyroidism) also have hypertension.
A cat’s normal blood pressure is about 124 mm Hg. Cats over 150 should be checked. Organs such as eyes and kidneys can be damaged because they do not receive the appropriate blood flow. Sometimes the initial symptoms are retinal damage or a cat suddenly goes blind.
Hypertension and kidney failure aggravate each other leading to progressive kidney failure.
Source: Cat Owner’s Home Veterinary Handbook.