March 24, 2013
Although blood pressure measurement has long been part of our routine physical exams when we go to the doctor, most pet owners arenít aware that high blood pressure (hypertension) can also be a concern for their pets. The reason veterinarianís havenít routinely made blood pressure measurement a part of routine examinations is because of not having an easy, noninvasive, accurate method of measuring the blood pressure on pets. Blood pressure machines for people are not accurate for pets. Even some of the units previously designed for pets leave a lot to be desired, but they were all we had to use. Now we have blood pressure units specifically designed for pets that are much more accurate.
Primary hypertension is the form seen in 95 percent of people with high blood pressure, meaning there is no underlying cause. Their disease is hypertension. In our pets, hypertension is almost always secondary to another condition. For the purpose of this article I want to focus on cats because they are much more likely to get some of these primary conditions which can result in hypertension.
Even with the newer technology, we still can have difficulty getting an accurate reading when pets come into the office. A ďnormalĒ blood pressure reading for cats is 124/84. Studies have shown that it will go up by 30 just during the car ride to the office, but will usually come back down to close to their normal within minutes of arriving at the vet office. Blood pressure can go back up by 30 during the examination, though. Cats that actually do have hypertension will have even more dramatic increases during these stressful times. So the best time to get an accurate reading is about 5 minutes after arriving at the vet office and before the examination begins. A more accurate true blood pressure reading is also accomplished by performing a minimum of four readings and averaging them. That way if the cat is stressed or startled the first time the blood pressure cuff blows up, there will be less of an effect with each subsequent reading as they get used to it.
The primary conditions seen in cats that can most often lead to hypertension are kidney disease, high thyroid disease, heart disease, diabetes and obesity. While hypertension doesnít occur in all cats with these conditions, when it does occur it creates further problems for cats. Consistent blood pressure over 160/100 creates a moderate risk to damage organs, and when over 180/120 it creates a severe risk for organ damage.
The most common area affected by hypertension in cats is the eyes. Hypertension can lead to retinal detachments and bleeding in the eyes. This causes the pupils to dilate and not respond to light anymore. It can lead to permanent blindness. Another organ damaged by hypertension is the kidneys. While kidney disease can lead to hypertension, the high blood pressure going through the kidneys can also damage them. A speaker I heard recently also feels that hypertension may also lead to headaches. Although cats canít complain about headaches, it does make sense that high blood pressure could cause headaches, especially considering the pressure can be high enough to cause retinal detachments. Some cats with hypertension where a primary cause couldnít be found yet and were treated for hypertension often acted better. These cats had been sleeping more and sought out quiet, dark areas. Once treatment brought the blood pressure down, these behaviors improved or went away altogether.
Treatment for hypertension may be as simple as giving an inexpensive medication once or twice daily. Conveniently, one of the medicines commonly used for hypertension is also commonly used to treat two of the causes of hypertension, kidney disease and heart disease. So if either of those conditions canít be diagnosed yet and is the primary cause of the hypertension, treatment may even help with them. Furthermore, if the primary cause of hypertension is treated and cured or controlled otherwise, the hypertension may resolve altogether.
Signs a cat owner should be looking out for that could indicate hypertension or the conditions that lead to hypertension include extremely dilated pupils, blindness, dramatically increased urination, poor appetite, weight loss, dull/disheveled coat, and seeking out quiet, dark areas. If your cat is showing any of these signs, an examination and evaluation of blood pressure and organ function can not only help your cat feel better, but dramatically lengthen your catís life.
Dr. Chad E. Higgins has owned Amanda Animal Hospital for the past 16 years. He sees dogs, cats, and other furry little critters.