The importance of maintaining a normal blood pressure is constantly stressed for humans. With hypertension comes increased risk for stroke, heart disease, renal disease and dementia. Billions of dollars are spent annually on medications to control blood pressure. It is so important in people that you can now check your own blood pressure at most pharmacies.
In humans, genetics contribute but so do our lifestyles. Everyone knows that obesity, smoking, stress and high-sodium diets will raise your blood pressure.
Even though obesity is the only risk factor pets share with us, they still can develop high blood pressure as they age. Usually their high blood pressure develops secondary to another disease process.
Probably the most common disease is chronic renal failure. The kidneys filter toxins from the blood and eliminate them from the body via urine. If the body senses the kidneys are not removing these toxins efficiently, it will raise the blood pressure to improve blood flow to the kidneys. At mild increases, this is beneficial; however, over time the increased blood pressure will damage the kidneys and further causing the renal failure to progress more rapidly.
The kidneys should not allow protein to spill into the urine. In the forms of renal disease, where protein is being lost, hypertension is even more likely to occur. Assessing for urine protein is important when your pet’s veterinarian is determining the degree and type of kidney failure your dog or cat has.
It is estimated that more than 80 percent of cats with hyperthyroidism will also be hypertensive. Fortunately, normalizing the thyroid hormone levels will usually correct the blood pressure.
Hyperadrenocorticism (also called Cushing’s disease) is a condition where the adrenal glands produce excessive amounts of their hormones. Hypertension may occur secondary to this disorder, but as for hyperthyroidism in cats, once the hormonal excess is corrected, the hypertension usually resolves.
There are also several less commonly diagnosed disorders that will increase blood pressure. Pheochromocytomas are another type of adrenal gland tumor that produces excess adrenaline. Acromegaly is a condition where the pituitary gland produces excess amounts of growth hormone. Polycythemia is a disease where there are too many red blood cells.
Primary hypertension can occasionally be diagnosed in pets without any underlying disease, but this is not as common in pets as in people.
The elevated blood pressure may cause vessels to rupture and bleed. Symptoms of this are commonly associated with the eyes and brain. Retinal detachment resulting in sudden blindness is the first symptom many cats with hypertension have. Seizures, trouble walking and altered mental activity may be seen if hypertension causes bleeding in the brain.
A condition called hypertrophic cardiomyopathy may develop if the heart has to pump blood against this increased pressure. The heart is like any muscle in that it hypertrophies if asked to work harder. This can result in abnormal heart beats and heart failure.
Since primary hypertension is not as common in pets as people, we do not routinely measure blood pressure in every patient. There are times when it should be checked however.
Any pet with renal disease. Maintaining a normal pressure is one of the few methods we have to slow the progression of renal disease.
Any pet with hyperthyroidism and hyperadrenocorticism. Even though correction of the hormonal excess often corrects the hypertension, the blood pressure may still need to be normalized. It is terrible to have a patient suddenly loose vision and then realize this was totally preventable.
Any pet diagnosed with cardiac disease. In cats we want to determine if the hypertension has caused the cardiac changes (especially hypertrophic cardiomyopathy). In dogs even mild elevation in blood pressure may worsen a leaky heart valve.
Measuring blood pressure in pets is not as easy as it is in humans. We cannot just listen for changes in blood flow with a stethoscope but must use a special device. Stress also is a complicating factor and will artificially increase blood pressure. We decrease the impact of stress by taking the measurements in a quiet room away from other animals and people. Multiple readings are taken (we try to get at least six) and average them together.
High blood pressure does occur in dogs and cats. Bringing levels back to normal may improve and prolong your pet’s life.
Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to firstname.lastname@example.org.