By Vet Adam Van den Broek
High blood pressure (HYPERTENSION) is a relatively common condition in cats and dogs, as it is in people, and is defined crudely as the force that is generated in the body’s blood vessels by the beating heart.
Normal systolic blood pressure ranges from 110-160mm of mercury, (Hg), and diastolic from 60-90mm of mercury. Anything that is consistently over 170mmHg in an unstressed cat, and 180mm Hg in a dog is considered high, although it should be stated that these figures are subjective.
At the clinic, hypertension is something more commonly diagnosed in cats than dogs, and is typically secondary to either renal disease or hyperthyroidism, which are both common conditions seen as cats get older.
In dogs, it is usually secondary to other underlying disease e.g. Cushing’s, which is also known as Hyperadrenocorticism.
Primary heart issues can also cause hypertension.
Sometimes what is called primary hypertension is diagnosed, without any obvious underlying cause, but this is less common.
CONSEQUENCES OF HYPERTENSION:
It can result in reduced blood flow to organs, with consequent damage, and reduced oxygen and nutrient supply to e.g. kidneys, heart, liver, and cause things such as blood clots in the legs, or even lungs, and therefore be life threatening.
The heart has to work harder to pump the blood around the body, so long term it can result in enlargement to the heart and eventually heart failure
Blood supply to the eyes and brain can be affected, resulting in loss of function and long term damage, bleeding in both the brain and eyes, retinal detachment, and blindness amongst other things.
BLOOD PRESSURE MEASUREMENT:
In practice blood pressure is measured indirectly in a similar way to that in your G.P. surgery or hospital, with the use of a cuff that is placed around your dog or cat’s leg or tail. It does not take very long to do and is fairly cheap as well, and given the potentially serious, and life-threatening consequences of hypertension if left untreated, it is essential that it is diagnosed early and treatment started.
Ideally blood pressure should be measured every year in animals over 10 years of age, and every 3 months if your pet is found to be suffering from hypertension, to assess response to treatment, but would largely depend on each case and this is something that we would discuss with you.
The most commonly used drug is one called Amlodipine ,and this is used once daily at the prescribed dose long term. Sometimes the dose may need to be increased, other drugs may be required if blood pressure is persistently high despite the treatment, for instance Benazepril, a drug known also as an “Ace inhibitor”.
Obviously the underlying cause also needs to be treated, or at least managed and controlled as best as possible also, in order to minimise the risk of secondary complications that can be life-threatening.