Hypertension
High blood pressure in dogs and cats: how vets measure it, why it often hides behind other diseases, and how treatment and monitoring work.
Also known as High Blood Pressure, Systemic Hypertension, Systemic Arterial Hypertension
High blood pressure, called hypertension in medical terms, means blood is pushing against the walls of your pet's arteries with more force than normal over a sustained period. It is not the brief rise anyone can get when excited or nervous. In dogs and cats, sustained high blood pressure is usually not a disease on its own. Most of the time it develops because of another long-term health problem, such as kidney disease, an overactive thyroid in cats, or Cushing's disease and diabetes in dogs. High blood pressure with no clear underlying cause is rare in pets.
What makes hypertension worth taking seriously is how quietly it can progress. Affected animals often look completely normal in the early stages, so vets treat it as something to catch through screening rather than something to wait and watch for. Over time, raised pressure gradually injures the organs with the most delicate blood vessels: the eyes, kidneys, brain, and heart. In the eyes, damage can appear as sudden blindness or bleeding into the front chamber of the eye. In the brain, it may cause seizures, disorientation, or balance problems. The heart may develop a murmur or thickened muscle, and sustained pressure on the kidneys can accelerate kidney damage, especially in a pet already living with kidney disease.
A vet measures blood pressure with a small inflatable cuff, usually placed around a leg or tail, while the pet rests in a quiet room. Because a nervous animal naturally has a higher reading, sometimes by 15 to 20 mmHg or more, a single high number at the clinic is not enough for a diagnosis. Vets confirm the pattern over separate visits. The number they focus on is the systolic pressure, the pressure while the heart is pumping. The American College of Veterinary Internal Medicine groups readings this way: below 140 mmHg is normal, 140 to 159 is a watch-and-wait range, 160 to 179 counts as hypertension, and 180 or above is severe.
Because it hides so well, screening matters. The International Society of Feline Medicine suggests checking cats once a year from about 7 to 9 years old, and twice a year from 11 onward. The reason is straightforward: high blood pressure affects roughly 20 to 35 percent of cats with chronic kidney disease, and up to 87 percent of cats with an overactive thyroid at their first visit.
Treatment depends on the species and the underlying illness. The International Society of Feline Medicine recommends amlodipine as the usual first choice for cats, while for dogs the American College of Veterinary Internal Medicine favors starting with a drug that acts on the hormonal system controlling blood pressure, such as an ACE inhibitor, with amlodipine added if needed. The aim is to bring blood pressure down, usually below about 150 to 160 mmHg, without dropping it so low that the pet becomes weak or sluggish. Rechecks help the vet fine-tune the dose.
If your vet mentions high blood pressure, it is usually a manageable part of caring for another condition rather than a separate emergency. The main steps are calm, repeat measurements and, when needed, daily medication with regular monitoring.