Hypertension: Putting Pressure on This Hidden Stranger

by Teresa Garden, DVM

Most of us are very familiar with getting our blood pressure checked during routine doctor appointments.  The cuff gets wrapped securely around our upper arm, next comes the pumping, and then the doctor or nurse gives us good news or bad.  Often, if our blood pressure is higher than normal, some simple lifestyle changes can be made to bring it down to normal.  We may need to lose weight, exercise more, and eat healthier.  More severe cases may require medications.  It may be surprising to learn that dogs and cats can have hypertension as well, but probably not related to their lifestyle choices.  Hypertension can  be a “silent killer” in pets, as well as in people, with no overt clinical signs being noticed.  Systemic hypertension in pets is an under-recognized disease that can cause significant end organ damage to the brain, retina, kidney, and heart.  Fortunately, veterinary medicine now has the technology to measure blood pressure in dogs and cats.

So how do we measure blood pressure in a squirming, wiggly cat or anxious, panting dog?  It isn’t always easy.  Our patients need a little time (5-10 minutes) to adjust to being in a vet clinic.  We try to make sure the surroundings are quiet and the owner can be with the pet to comfort and calm them.  We use a little portable machine that measures the pressure once a cuff has been applied to the leg or tail.  The pets are usually sitting or lying down with minimal restraint.  We take several readings (5-7) and then use the average to determine if pressure is normal or high.  The procedure is painless and takes only a few minutes.  Dogs and cats are considered to be hypertensive if the systolic reading is consistently above 180mmHg  and diastolic above 110mmHg.

Hypertension in dogs and cats can be a primary disease, but most often it is associated with other diseases.  If your pet has been diagnosed with heart disease, kidney disease, liver disease, diabetes, certain cancers, or obesity, then hypertension may also be lurking within his or her body.  Dogs with Cushing’s disease and cats with hyperthyroidism are also at risk for hypertension. Some commonly used medications can cause hypertension: aminophylline, theophylline, prednisone, NSAIDS, and phenylpropanalamine. Often there are no symptoms of hypertension.  Sometimes there will be red flags.  Acute blindness, dilated pupils, heart murmurs, collapse/syncope, seizures, and epistaxis (bleeding from nostrils),  can be symptoms of hypertension that may be associated with underlying illnesses.  If underlying illnesses are diagnosed and treated properly, then often hypertension will resolve.  If hypertension is not recognized, damage to the eyes, brain, heart, and kidneys may ensue.  Eye damage leads to retinal edema or hemorrhage and retinal detachment causing blindness.  Cerebral injury leads to edema or hemorrhage of the brain.  Symptoms of this would be abnormal mentation, head tilt, seizures, and coma.  Heart damage can be heard as a murmur or gallop rhythm.  Kidney disease can lead to hypertension but primary hypertension can cause kidney damage.  This may present as abnormal size or shape of the kidney(s), protein in the urine, or elevated kidney enzymes.  Senior pets should be routinely screened for hypertension during their annual exams because they are more at risk for underlying illnesses associated with hypertension.

So what should be done if your pet has high blood pressure?  First, your veterinarian needs to determine if there is an underlying disease.  Once this entity is identified and treated, the hypertension may resolve.  Examples of this would be treating heart disease or hyperthyroidism.  If hypertension is identified along with kidney disease, then the hypertension is usually treated before it does any further damage to the kidneys. If blood pressure is found to be extremely high (>250 mmHg) then it is immediately treated aggressively to prevent possible blindness and neurological symptoms.  Cats are treated with Norvasc (a calcium channel-blocking agent) and dogs are treated with Hydralazine.  Treatment can be more conservative if pets are asymptomatic and if their pressures are not dangerously high.  Ace-inhibitors such as Enalapril or Benazepril are often employed for these situations and for those pets with kidney disease.  Once a pet is started on therapy blood pressure should be rechecked in 7-14 days and then about every 3-6 months thereafter.  Each pet is treated as an individual and each will respond differently to the medications used.  Sometimes if one drug does not work, another can be tried.  Sometimes combination therapy will be needed.  The goal is to diagnose and treat high blood pressure before this “hidden stranger” causes damage to your precious pet’s body.

Dr. Teresa Garden is chief veterinarian/owner of Animal Health & Healing, a full-service holistic and conventional veterinary practice in the Maplewood/Richmond Heights area. AnimalHealthandHealing.com; phone: 314-781-1738.