September 24, 2017

High Blood Pressure in Dogs

Everyone knows that stress can lead to high blood pressure.   Worrying about finances, eating too much fast food, and being addicted to nicotine certainly raises our blood pressure.  But do our dogs get affected?   They certainly don’t smoke or worry about bills, so why are veterinarians worried about “doggie hypertension”?

The faces in the exam room were grave.  Their doctor had just explained that dietary changes and potential exercise changes may be necessary.  A long-term, probably life time medication would need to be started.  The problem was a blood pressure reading well in excess of normal.   Meanwhile, the patient continued to chew on his treat and wag his tail, clueless to the concern of the humans in the room.

Most dog owners would admit a lack of knowledge or perhaps even a lack of concern about canine hypertension, or high blood pressure in dogs.  After all, since they don’t have the same vices as we do, they shouldn’t be at risk, right?  Well, the answer may be a little more complex than just life style choices.

One study showed that 93% of dogs with chronic kidney disease also suffer from high blood pressure.  Other studies cite that more than 60% of geriatric dogs (over 8 years old) also suffer from this often silent disease.  One reason that so little is known about how many dogs are actually affected is the fact that blood pressure measurements are not routine during your pet’s office visit.   Considered to be one of five vital signs for humans, blood pressure in our pets has not received the same attention and thus, inconsistent measuring practices and varying guidelines have made it difficult to determine what values are currently accepted as borderline or mild hypertension in pets

Blood pressure in humans is measured by gently occluding, or blocking, an artery in an arm or leg.   A stethoscope is then used to listen for the return of the pulse as the pressure is slowly released.   This point is known as the systolic blood pressure, or the higher of the two numbers you will hear or read.   Next, the pressure continues to be released and when no pulse sounds are heard, that pressure is called the diastolic pressure.   Blood pressure is then read as systolic over diastolic, or, for example, 140 over 80.  For dogs, the stethoscope is often not sensitive enough to hear the pulse sounds and it is virtually impossible to detect the diastolic signal.  Most veterinarians will simply record a pet’s blood pressure as the systolic measurement, or, for example, 180.  Many veterinarians who utilize blood pressure measurements use an ultrasonic probe to “hear” when the pulse returns to the artery.  The probe will then convert that signal into an audible sound for the doctor.   Experts caution both veterinarians and owners to never become alarmed at a single high reading.   The important thing to remember is that the results must be repeatable.

Primary hypertension, or high blood pressure with no other disease, is very common in humans but not so in our pets.   Dogs often suffer from secondary hypertension, or high blood pressure due to some underlying disease process.   The most common canine diseases that can lead to high blood pressure are chronic kidney disease, Cushing’s disease (an overproduction of cortisone by the body), hyperthyroidism, and  adrenal gland tumors .  With high blood pressure, blood vessels can become thickened and stretched and may eventually rip and tear, causing bleeding.  This may not be immediately noticeable, but as small vessels in the eye and in the kidneys begin to be destroyed, patients will begin to show clinical signs.   Symptoms of high blood pressure are often unnoticed by the owner.  A sudden or gradual onset of blindness can be the only outward sign that your pet may have high blood pressure.  High blood pressure can worsen existing kidney disease, can cause bleeding in the brain, and will eventually affect every organ in the body.

Fortunately for our pets, since high blood pressure often results from another disease process, controlling the first disease will often reverse or help to control the high blood pressure.   As with humans, certain drugs are available to help relax and dilate blood vessels, lessening the pressure from the blood flow.  Your veterinarian may also recommend a salt restricted diet for your pet to help decrease blood pressure levels.  Finally, routine blood screening and routine blood pressure measurements will become vitally important to the health of your pet.

With so little known about the true numbers of dogs suffering from hypertension and a lack of consistent means of measurement, we may never know how many of our canine companions are affected by this silent disease.   The American College of Veterinary Internal Medicine has created a Hypertension Task Force to help answer this and many other questions.  Visit www.MyVNN.com to see a video showing a dog having his blood pressure measured and ask your veterinarian about your pet’s blood pressure, especially if your dog is over 9 years old.

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