High Blood Pressure in our Pets

High Blood Pressure in our Pets

by Dr. Ed Mapes
Stonebridge Animal Hospital
McKinney, Tx

Elevated blood pressure, or systemic hypertension, is a well-recognized health risk in humans; but did you realize that hypertension is being identified more and more as a cause of illness in pets as well? With the advent of modern Doppler monitor technology, obtaining blood pressure readings is now more reliable than in years past, and the information we’re getting has been a surprise. Hypertension usually arises secondarily to other diseases in cats and dogs. In other words, they incur another disease first, and that causes hypertension to develop. It is a complicating factor that results in its own set of clinical signs, and these can make diagnosing the primary illness more difficult. Some symptoms caused directly by high blood pressure include:

  • detached retinas with intra-ocular bleeding
  • acute blindness -bloody nose (epistaxis)
  • development of heart murmur with heart chamber enlargement
  • decrease in energy levels and vigor
  • changes in behavior
  • seizures

A rapid increase in pet obesity has brought about more cases of diabetes and Cushing’s syndrome (hyperadrenocorticism) in our pets. Both of these diseases are known to cause hypertension, so that accounts for much of the increased incidence.

Renal diseases comprise another set of disorders very commonly seen in pets as, and kidney disorders can also cause hypertension. This is especially insidious, because the symptoms of early kidney disease (increase in thirst and urination, minor decreases in appetite, occasional vomiting) are subtle and very often missed by owners. That being the case, the disease is able to progress slowly over time.

The animal’s body reacts to decreased kidney function, and produces a hormone that stimulates production of substances directly responsible for elevating blood pressure and causing fluid retention. By the time we see these patients, the kidneys are already in more advanced stages of disease and the blood pressure is sometimes already high.

Along with these diseases, cats are also prone to elevated levels of thyroid hormone levels (hyperthyroidism) and high blood pressure arises with this too. Many of these cats have heart disease that is complicated by hypertension, and lowering the pressure can be very important in the treatment of these cases.

We veterinarians should always include a test to determine blood pressure when examining patients with these diseases and those with symptoms of high blood pressure. Taking the time to test the pressure is well worth the effort because identifying these patients and providing treatment is so important to returning them to health.

Most patients require therapy to treat the underlying disorder in conjunction with medications to relieve hypertension. There are two different mechanisms in the body – the autonomic nervous system and the endocrine (hormones) system – that regulate blood pressure, and we must often provide controls over both systems. A medication that directly dilates blood vessels is often combined with another type of drug to control the hormones produced by the body that elevate blood pressure.

Figure 1 with the cuff positioned on the kitten’s rear leg, we’re measuring her blood pressure.

Figure 1 with the cuff positioned on the kitten’s rear leg, we’re measuring her blood pressure.

Blood pressure in animals is determined by placing an inflatable cuff on a foreleg, rear leg, or near the base of the tail. The monitor automatically inflates the cuff and provides a read-out of both systolic and diastolic pressures. We eliminate the first reading, and then take six more to arrive at a suitable average. The procedure is painless, and in most animals takes but a minute. This is also one of the devices we use during anesthetic procedures to ensure safety.

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