Like in humans high blood pressure can affect the health of our pets. Hypertension (high blood pressure) occurs in dogs and cats but this blog will focus on cats. At North Hill Animal Hospital, we most commonly measure systolic blood pressure. This is the pressure against the walls of the blood vessels when the heart is contracting. A normal value in a cat is 120-130 mmHg with measurements greater than 160 mmHg considered systemic hypertension.
Blood pressure is monitored in awake patients and is also an important vital sign during a general anesthetic. We mainly use a Doppler system to measure blood pressure. Unlike humans, we cannot use a stethoscope to hear the return of blood pressure once a cuff is deflated. The Doppler system uses a transducer that generates ultrasound waves which detect re-entry of blood into the occluded artery. Essentially the transducer (hooked up to a speaker) acts as our ears. A cuff similar to that used in humans is used on the cat’s limb or tail. As you can imagine this process can be a challenge in an awake cat!
Stress is a major complicating factor when trying to get an accurate blood pressure reading. The “white coat” effect can increase blood pressure significantly so we try to make the process as stress-free as possible. This usually means the owner is present or even holding the cat for the measurement.
Hypertension in cats is most often a result of a disease process, the most common being kidney disease and hyperthyroidism. Symptoms of high blood pressure can be subtle and non-specific such as decreased appetite and low energy. The most common sign of severe hypertension is a sudden loss of vision, caused by hemorrhage of the blood vessels at the back of the eye. Other signs can result from “a stroke” or hemorrhage in the brain e.g. seizures, head-tilt or wobbly movements.
Treatment involves addressing the primary problem if possible for example using medication to lower the thyroid level in a hyperthyroid cat. If blood pressure is high due to kidney disease medication such as amlodipine and benazepril are used long-term to dilate arteries, therefore, dropping blood pressure. Hypertension over time can worsen kidney disease and weaken the heart.
Written by Dr. Dana Cini, DVM