High Blood Pressure (Hypertension) and Your Pets
High Blood Pressure (hypertension) is very common in our pets, but often goes undiagnosed until it leads to life threatening emergencies. Problems from high blood pressure arise when a blood vessel gets too small for the high pressure flow going through it. Since the affected vessels are small, the bleeding may not be noticeable but a lot of little bleeds and a lot of blood vessel destruction can create big problems over time.
Your pet’s retina is especially at risk, with either sudden or gradual blindness often being the first sign of latent high blood pressure. The kidneys are also targets since they rely upon tiny vessels to filter toxins from the bloodstream. High blood pressure also increases the risk of embolism: tiny blood clots that form when blood flow is abnormal. These clots can lodge throughout your pet’s body – including the brain.
But our pets do not have the same “external pressures” that can often trigger hypertension in their pet parents, so what causes this condition in our pets? There are numerous diseases in pets that are associated with high blood pressure, including:
Chronic renal (kidney) failure– in one study, 93% of dogs with chronic renal failure and 61% of cats with chronic renal failure also had systemic hypertension; Hyperthyroidism– in one study, 87% of cats with untreated hyperthyroidism had systemic hypertension (hyperthyroidism is a feline disease only!); Glomerular disease– disease of the kidney filtration system in which protein is lost in urine. It is important to screen pets with high blood pressure for urinary protein as control of protein loss is important to survival time; Cushing’s disease (an adrenal cortisone excess) ; Diabetes mellitus (inability to properly reduce blood sugar) ; Acromegaly (growth hormone excess); Polycythemia (an excess in red blood cells) ; Pheochromocytoma (an adrenaline secreting tumor of the adrenal gland)
High blood pressure can be identified by screening at your veterinarian’s office. If your pet has one of the above-mentioned conditions, their blood pressure is generally checked. Older pets should have their blood pressure checked whenever they have a physical examination, particularly if they are over the age of 9.
Sadly, high blood pressure is discovered only after something untoward has happened to your pet physically (i.e. some degree of blindness or some other eye problem.) The retina of a hypertensive pet 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 detach, or the entire retina detaches. With early identification, some vision may be restored, so do not let minor vision changes go unreported; tell your veterinarian know if you think your pet’s vision is abnormal.
Retinal changes can be complicated to interpret. Be prepared if your veterinarian refers you to a veterinary ophthalmologist. (Be sure to consult your veterinary insurance provider, as many cover specialist visits such as this.)
Blood pressure measurement is performed with an inflatable cuff fitted snuggly around your pet’s foot or foreleg; sometimes, the base of their tail can be used. The cuff is inflated to prevent blood flow through the superficial artery. With pets, an ultrasonic probe must be taped or held over the artery, and the sound of the systolic pressure is converted into an audible signal. In pets, this measurement should not exceed 160; a reading of 180 is considered by the American College of Veterinary Internal Medicine to indicate high risk for organ damage.
There are various treatment options for hypertension. When ocular disease is present, special eye drops may be required, depending upon how much the eye is bleeding and whether or not return of vision is likely; (a veterinary ophthalmologist is especially helpful in this scenario.) When hypertension is identified, a search for the underlying cause is indicated. It may be that controlling the underlying disease totally reverses the hypertension (particularly true for hyperthyroid cats).
Beyond these methods, as with people, blood pressure lowering medication is prescribed. This typically involves some type of pill that dilates peripheral blood vessels, making them larger to accommodate the high pressure blood flow going through them. Dietary restrictions may also be recommended by your veterinarian. Hypertensive patients should be rechecked every 2-4 months to keep their blood pressure in a healthy range.
