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By Dr. McDivitt
Published: April 28, 2011

High Blood Pressure in Cats
Problems from high blood pressure arise when a blood vessel gets too small for the high pressure flow going through it. When the pressure inside a blood vessel increases, the blood vessel can bleed or "leak." 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. The retina of the eye is especially at risk, with either sudden or gradual blindness often being the first sign of latent high blood pressure. The kidney also is a target as it relies on tiny vessels to filter t
High Blood Pressure in Cats
Problems from high blood pressure arise when a blood vessel gets too small for the high pressure flow going through it. When the pressure inside a blood vessel increases, the blood vessel can bleed or "leak." 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. The retina of the eye is especially at risk, with either sudden or gradual blindness 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. High blood pressure also increases the risk of tiny blood clots (embolil) that form when blood flow is abnormal. These clots can lodge in the brain, the lungs, or the distal portions of the vessels supplying the back legs, causing paralysis (called "saddle thrombi" in cats).

What Causes High Blood Pressure?
High blood pressure is typically not a primary disease; there is usually an underlying disease process causing the hypertension. Routine screening tests can uncover:
How is High Blood Pressure Identified?
In pets, a great deal of high blood pressure is identified by screening. If a cat has one of the above conditions, blood pressure is generally checked. We recommend that older cats have their blood pressure checked whenever they have a physical examination, ideally every 6 months. The other time high blood pressure is discovered is when it manifests as systemic disease. A common presentation in cats is blindness secondary to retinal detachment. Owners typically report that their cat is bumping into things, can’t find the litter box, or is howling constantly (worse at night). 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.

How do we measure blood pressure?
Blood pressure measurement is performed similarly to the way it is in humans. An inflatable cuff is fit snuggly around the cat’s rear leg. The cuff is inflated so as to occlude blood flow through the superficial artery. In animals, an ultrasonic probe must be taped or held over the artery. Using ultrasound, 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. Some pets (obviously) are nervous at the vet’s office and this factor must be taken into account when reading blood pressure. It is possible for a pet to have high blood pressure at the vet’s office and normal pressure at all other times. We typically take several readings to be sure we are getting an accurate result.

What Treatment is Available for Hypertension?
When ocular disease is present, special eye drops may be required depending on how much the eye is bleeding and whether or not return of vision is likely.
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).
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. Amlodipine, a calcium channel blocker, is the usual first choice for cats. It is typically given once daily. Dietary recommendations usually mean a dry or canned formula prescription diet if the pet will eat it or a diet limited to dry food if the pet will not accept prescription food.
oxins from the bloodstream. High blood pressure also increases the risk of tiny blood clots (embolil) that form when blood flow is abnormal. These clots can lodge in the brain, the lungs, or the distal portions of the vessels supplying the back legs, causing paralysis (called "saddle thrombi" in cats).
What Causes High Blood Pressure?
High blood pressure is typically not a primary disease; there is usually an underlying disease process causing the hypertension. Routine screening tests can uncover:
How is High Blood Pressure Identified?
In pets, a great deal of high blood pressure is identified by screening. If a cat has one of the above conditions, blood pressure is generally checked. We recommend that older cats have their blood pressure checked whenever they have a physical examination, ideally every 6 months. The other time high blood pressure is discovered is when it manifests as systemic disease. A common presentation in cats is blindness secondary to retinal detachment. Owners typically report that their cat is bumping into things, can’t find the litter box, or is howling constantly (worse at night). 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.
How do we measure blood pressure?
Blood pressure measurement is performed similarly to the way it is in humans. An inflatable cuff is fit snuggly around the cat’s rear leg. The cuff is inflated so as to occlude blood flow through the superficial artery. In animals, an ultrasonic probe must be taped or held over the artery. Using ultrasound, 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. Some pets (obviously) are nervous at the vet’s office and this factor must be taken into account when reading blood pressure. It is possible for a pet to have high blood pressure at the vet’s office and normal pressure at all other times. We typically take several readings to be sure we are getting an accurate result.
What Treatment is Available for Hypertension?
When ocular disease is present, special eye drops may be required depending on how much the eye is bleeding and whether or not return of vision is likely.
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).
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. Amlodipine, a calcium channel blocker, is the usual first choice for cats. It is typically given once daily. Dietary recommendations usually mean a dry or canned formula prescription diet if the pet will eat it or a diet limited to dry food if the pet will not accept prescription food.

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