BLOOD PRESSURE MONITORING

• Blindness - The retina is especially at risk. Sudden or gradual blindness can be a first sign of latent high blood pressure.


• Renal Failure - The kidneys are made up of many tiny vessels that filter toxins from the bloodstream.  Kidney disease is an important cause of high blood pressure.  Diseased vessels no longer expand properly causing greater resistance to blood flow through the kidneys.  Kidney disease progresses more rapidly when high blood pressure is left untreated.


• Embolism - Abnormal blood clots that can lodge in many locations through the body.  Embolisms can cause strokes, heart attacks, and other life threatening and fatal problems.

Hypertension also places a strain on the heart. The heart must pump against higher vascular resistance, causing further deterioration.   Over time the heart enlarges and a murmur (An extra sound, such as a whooshing, in the heartbeat caused by irregular blood flow through the heart valves.) can be heard through a stethoscope.

COMMON CAUSES OF HYPERTENSION IN PETS

• Acromegaly - Excess of growth hormone.


• Chronic Renal Failure - Many cats and dogs with chronic renal failure also have systemic hypertension.


• Diabetes Mellitus - A group of metabolic diseases characterized by high blood sugar (glucose) levels, which result from defects in insulin secretion, or action, or both.


• Glomerular Disease - Affects kidney function by attacking the glomeruli, the tiny units within the kidney where blood is cleaned.


• Hyperthyroidism - (cats only) Cats with untreated hyperthyroidism frequently have systemic hypertension.


• Polycythemia - Excessive production of red blood cells as a result of an abnormality of the bone marrow. Can also cause an excess white blood cells and platelets to be produced.


• Pheochromocytoma - Tumor of the adrenal glands. The adrenal glands are glands that sit on top of the kidneys.

HOW IS HYPERTENSION IDENTIFIED?

High blood pressure in humans is called “the silent killer” because many people are unaware of it until they have a catastrophic occurrence, like a stroke. Regular measurement of human blood pressure is the best way to diagnose hypertension. Hypertension in pets is often identified by screening. A pet that has been diagnosed with one of the diseases listed above should have its blood pressure checked frequently.If your pet over age nine years old you may want to request a blood pressure check to be used as a baseline measurement.

Hypertension is also diagnosed when a condition or disease is recognized that has high blood pressure as one of its complications. A blood test may indicate one of the diseases that cause high blood pressure, the pet may become blind, or changes may be observed on examination at our office.  As with other diseases early identification and treatment are of utmost importance.

HOW BLOOD PRESSURE IS MEASURED

Your pet's blood pressure is measured similarly to yours.  An inflatable cuff is fitted around the foot or foreleg or base of the tail.  The cuff is inflated to occlude blood flow through the superficial artery. Unlike humans, a stethoscope is not sensitive enough to allow us to hear and measure an animal's blood pressure.  Rather an ultrasonic probe is taped or held over the artery. The ultrasonic probe converts sound of the systolic pressure into an audible signal. Diastolic pressure can only be measured by placing a catheter inside an artery.  So typically the systolic measurement is the only measurement we use. 

A cat with a systolic pressure over 170-180 mm Hg is considered hypertensive. In dogs 180 mm Hg is considered high. Sight hounds, overweight, and older animals tend to have higher readings. These numbers are a guideline. An individual animal's measurements can vary from these guideline figures.

Since some pets are nervous at the vet’s office we take this factor into account when reading blood pressure. 
It is possible for a pet to have high blood pressure at the vet’s office and normal pressure at all other times but typically even the stress of a visit to the vet does not alter the animal's blood pressure.

TREATMENT FOR HYPERTENSION

When ocular (eye) disease is present, you may be given a prescription for eye drops.  These eye drops are only useful when bleeding is present in the eye and when return of vision is a possibility. When there is ocular disease we may refer your pet to a veterinary ophthalmologist.

When hypertension is identified it is important to learn what underlying disease is causing it. Control of underlying disease may reverse the hypertension.  (This is often the case in hyperthyroid cats).

The pet may be placed on a special diet that restricts salt intake.

There are several prescription medications available that dilate peripheral blood vessels.  Dilated vessels offer less resistance to blood passage effectively lowering blood pressure. 

• ACE Inhibitors - Drugs that inhibit ACE (angiotensin converting enzyme) which is important to the formation of angiotensin II. Angiotensin II causes arteries to constrict which raises blood pressure. ACE inhibitors lower the blood pressure by inhibiting the formation of angiotensin II. The result is that arteries relax.  Relaxed arteries lower blood pressure and improve the pumping efficiency the heart.


• Beta-Adrenergic Blockers - Decrease the heart rate.


• Calcium Channel Blockers - Decrease vascular resistance.


• Diuretics - Cause fluids, locked up in the body tissues, to be released and expelled in the urine. The effect is lowering of blood pressure, particularly in the aorta and pulmonary artery.


• Vasodilators - Decrease vascular resistance

When hypertension is diagnosed it is very important that the pet owner follow prescribed plans closely.  We will provide you with a recommended schedule for follow up examinations, blood panels, thyroid tests, urinalysis, and eye exams all of which help us monitor your pet's progress.