HIGH BLOOD PRESSURE IN PETS
HIGH BLOOD PRESSURE
The retina of the eye is especially at risk, with blindness (either sudden or gradual) often being the first sign of latent high blood pressure. The kidney also is a target as it relies on tiny vessels to filter toxins from the bloodstream. Kidney disease is an important cause of high blood pressure and also progresses far more rapidly in the presence of high blood pressure.
High blood pressure also increases the risk of “embolism:” the formation of tiny blood clots that form when blood flow is abnormal. These clots can lodge in an assortment of inopportune locations including the brain.
WHAT CAUSES HIGH BLOOD PRESSURE IN PETS?
There are numerous diseases in pets that are associated with high blood pressure:
In humans, high blood pressure is frequently considered “primary” meaning there is no underlying disease causing it. In animals, primary hypertension is unusual; there almost always is another disease causing it and if routine screening does not identify the problem, more tests may be in order.
HOW IS HIGH BLOOD PRESSURE IDENTIFIED?
In human medicine, high blood pressure is called “the silent killer” because most people have no reason to think they might be hypertensive. To find high blood pressure in people, we screen for it. This means that virtually any time you see a doctor of any kind, a nurse will take your blood pressure. Similarly, in pets, a great deal of high blood pressure is identified by screening for it. If a pet has one of the above diseases conditions, blood pressure is generally checked. It has recently been recommended that older pets have their blood pressure checked whenever they have a physical examination. There is some disagreement among experts as to which patients should be screened. Because of inherent insensitivity of the equipment commonly used in veterinary practice, not every pet necessarily needs to be screened. Certainly, any pet with a predisposing condition such as one of those listed above should be screened. Ask your veterinarian if your senior pet should get a blood pressure measurement.
The other time high blood pressure is discovered is when it makes its presence known. This usually means some degree of blindness or some other obvious eye problem. The retina of a hypertensive patient develops tortuous looking retinal blood vessels. Some vessels may even have broken showing smudges of blood on the retinal surface. Some areas of the retina simply detach. Sometimes the entire retina detaches. With early identification, some vision may be restored. Do not let minor vision changes go unreported. Let your veterinarian know if you think your pet’s vision is not normal.
Retinal changes can be complicated to interpret. Do not be surprised or alarmed if your veterinarian recommends referral to a veterinary ophthalmologist. To find a local ophthalmologist, click here.
HOW DO WE MEASURE BLOOD PRESSURE IN PETS?
Some pets (obviously) are nervous at the vet’s office and this factor must be
WHAT TREATMENT IS AVAILABLE FOR HYPERTENSION?
When ocular disease is present, special eye drops may be required depending on how much bleeding is present in the eye and whether or not return of vision is likely. (Here is one area where an ophthalmology specialist may be especially able to help.)
When hypertension is identified, a search for the underlying cause is indicated. It may be that controlling the underlying disease totally reverses the hypertension (especially true for hyperthyroid cats).
Beyond these methods, as with people, medication to actually lower blood pressure is often in order. This typically involves some type of pill that dilates peripheral blood vessels, effectively making them larger so as to accommodate the high pressure blood flow going through them.
Enalapril, an angiotensin converting enzyme inhibitor, is the usual first choice for dogs. It is typically given once or twice daily. Benazapril is another commonly used angiotensin converting enzyme inhibitor (also called an "ACE inhibitor") and might be used in either dogs or cats.
Amlodipine, a calcium channel blocker, is the usual first choice for cats. It is typically given once daily. These pills are very small, so we recommend that the owner buy a pill cutter for more accurate dosing. Alternatively, a Compounding Pharmacy may be used to create accurately sized capsules or even a flavored liquid.
Sometimes both amlodipine and an ACE inhibitor are combined for a better effect.
RESEARCH ON THIS TOPIC
Effect of Control of Systolic Blood Pressure of Survival in Cats with Systemic Hypertension. Jepson, R.E., Elliott, J., Brodbelt, D., Syme H.M. Journal of Veterinary Internal Medicine 2007; 21: 402-409.
In this study 141 pet cats with high blood pressure were studied. In these cats, 87% were found to have either evidence of renal failure (increased BUN or creatinine tests) or hyperthyroidism or both. Amlodipine besylate was used to treat hypertension in these cats and in 50% of the cats, the initial dose eventually proved inadequate and an increase was necessary. Blood pressure was stabilized within 1-2 recheck visits for 96% of cats, with a median time of 20 days required to achieve blood pressure stabilization. Blood pressure was more difficult to control in the long term for cats with higher urinary protein loss.
Page last updated: 10/7/2013