Understanding Hypertension in Pets
We did not think high blood pressure was a problem in our companion animals until fairly recently. Serious research about blood pressure in dogs and cats began a little over 20 years ago. Now we know that high blood pressure is linked with some serious diseases in dogs and cats and needs to be monitored.
Blood pressure is the pressure the blood exerts as it flows against the blood vessels. High blood pressure (hypertension) is an abnormal elevation in that pressure, which can lead to serious problems in pets and people. High blood pressure is much more common in humans than in animals. Many people have essential or primary hypertension, not linked to any other medical condition. Animals rarely have primary hypertension. They have secondary high blood pressure, caused by conditions such as kidney disease, Cushing’s disease, hyperthyroidism and diabetes. The primary disease must be treated, and the high blood pressure must be addressed.
People have much more high blood pressure than pets, often because of lifestyle. When is the last time you saw your Doberman walk through the door with a carton of cigarettes and a bottle of vodka? When did he last order a double cheeseburger and fries? And picking up the salt shaker to sprinkle on his kibble before he tastes it? And how about the stress in your pet’s life as a risk factor? As we run around like mental maniacs juggling jobs, children, spouses and the rest, what are your cats doing? They are considering whether or not to leave the couch to get a snack. For most well-cared-for pets, they live a fairly stress-free life!
Getting a Reading
At a recent vet visit, your veterinarian might have suggested taking a blood pressure measurement on your dog or cat. Something in your pet’s history suggested that high blood pressure might be a problem, or a blood pressure reading may have been part of a geriatric work-up. Blood pressures are not taken routinely because 1.) hypertension is not a very common finding, and 2.) there is still a large margin of error when measuring blood pressure in dogs and cats. We attribute this to the “white coat” phenomenon and the difficulty in taking measurements in animals under 15 pounds.
Many of you can relate to the white coat issue. Does your anxiety level rise as soon as you walk into your physician’s office? Mine does. And gazing at a fish tank, proven to lower blood pressure in humans, does not have the same effect on kitties!
There are two ways to measure a pet’s blood pressure: with a doppler or an oscillometric meter. Using either of these instruments requires technique and patience on the veterinarian’s part and calmness and patience on your part.
I like to have the owner in the room for a calming effect. Yelling at the top of your voice about how cute the little “cuffs” are and petting Fluffy uncontrollably while cackling about how your blood pressure goes through the roof at the doctor’s office is not conducive to lowering your cat’s blood pressure. Your soothing presence and low voice is what we need while trying to get several readings.
If I know I’m going to take a BP, I try to get the pet into a quiet room quickly, away from the waiting room. The general rule is to let the pet acclimate to the new surroundings and take a blood pressure in a few minutes. If the kitty or pooch seems more relaxed after the exam, I take the blood pressure again and compare them.
Generally, I try to take at least three or four readings and get an average. If the readings are high, and the animal has a condition that can cause hypertension, then blood pressure medicine should probably be prescribed. Lowering the salt content of the food is also a good move at this point. Once the primary disease is identified and controlled, blood pressure medicine may not have to continue. If we lower the blood pressure too much or continue to medicate when it is not necessary, your pet can become weak and dehydrated from low blood pressure, and that can also be dangerous.
Kidney disease in cats is one of the primary causes of secondary high blood pressure. Hypothyroidism is the other major cause. Many geriatric cats suffer from chronic renal failure and hyperthyroidism, making them prime targets for hypertension. Treating high blood pressure when present in a cat with failing kidneys prolongs and improves quality of life. The most common drug I prescribe for these cats is a calcium channel blocker called amlodipine.
If your cat suffers from hyperthyroidism alone, treating the thyroid disease may bring the blood pressure back to normal without additional medication, or the amlodipine may be needed only for a short time.
Dogs can also develop high blood pressure if they are in kidney failure and can be medicated as well. If your animal has been placed on blood pressure medicine, depending on the severity and concurrent disease, I usually recheck another blood pressure in one to three weeks. Some of these medications also require blood checks to ensure that the medication isn’t actually hurting the kidneys. Then, follow your veterinarian’s advice on monitoring.
Cushing’s disease (hyperadrenocorticism) is another major cause of high blood pressure in the dog. Treating the high blood pressure along with treating the Cushing’s can reduce the risk of stroke-like events that plague Cushing’s dogs. (Cats can get Cushing’s disease, but it is rare and virtually untreatable.)
Diabetes can cause high blood pressure. This is more of a problem in diabetic dogs than diabetic cats. Blood pressure should be monitored in these pets.
Symptoms of High Blood Pressure
The most serious clinical manifestations of untreated hypertension are ocular and neurologic emergencies such as acute blindness, seizures and vascular “accidents” that resemble strokes. Obviously these can be fatal in some instances. In these cases, if hypertension is found, lowering the blood pressure quickly is essential if the pet is to regain function or to survive. In most cases, however, hypertension is more of a chronic condition that can be managed over a period of months as you work to lower blood pressure and treat the primary disease.
I think we still have a lot to learn about diagnosing and monitoring blood pressure in cats and dogs. Some animals have been misdiagnosed as having hypertension and are on unnecessary blood pressure medication. This is because of an inaccuracy in measurements and “the white coat” effect.
Other animals are walking around like ticking time bombs because high blood pressure can have an insidious onset, be asymptomatic, and thus go undiagnosed. As our ability to measure blood pressure more accurately improves, so will the treatment.
If your animal has been diagnosed with one of the diseases I mentioned above, or if you have noticed anything different in the mental behavior or eyesight in your older pet, see your veterinarian to discuss possible causes. Be patient about the blood pressure measurements. You may have to go back for another visit to confirm readings. Some feline specialists even suggest a home visit if the cat is fractious or extremely stressed in the veterinarian’s office.
I feel great when I can make an accurate diagnosis of high blood pressure and improve an animal’s lifestyle, ward off a serious or fatal incident, or reverse an ocular or neurologic emergency. When people see the improvement in their pets, they remember that BooBoo needs to TAKE THAT MEDICINE!
And for yourself: Let’s work on lowering your blood pressure. Stop the smoking! Watch the partying! Lay off the extra salt! Get out and take a stress-free dog walk! And then go home and pet that great dog of yours. It’s proven to lower blood pressure.