How do I know if my cat has high blood pressure?

This is Kitty - why is she falling?

Does this cat look like she has high blood pressure? It's hard to tell from the outside, so routine testing, or "screening" is usually the best way to tell.

Most of the time, when we diagnose cats with high blood pressure, their owner has no specific complaints about their cat's health or behavior. That is because most of the negative effects of high blood pressure in cats are subtle, and act internally before outward signs are seen.

One of the most common causes of sudden blindness in cats is high blood pressure. This is because the tiny blood vessels are put under a lot of strain when a cat has chronic high pressure. This can cause the vessels to rupture or break and small areas of the retina lose blood supply. Once the blood supply is gone, small lesions or detachments form, giving your cat spotty vision. If this goes on for long enough, the entire retina can detach and cause complete blindness.

Fortunately, if high blood pressure is caught early, before too much retinal damage has been done, the lesions can heal, with treatment.

This particular cat was brought in to have an exam because she was wobbly and had started falling off a chest of drawers where she liked to sleep. The only thing that was found on her exam was that she had high blood pressure and some changes to the retina:

So, that's one problem on her list - but is her high blood pressure making her fall?

Sometimes, when a cat has high blood pressure, it is due to the presence of another disease, such as kidney disease, or hyperthyroid disease. In fact, 61% percent of cats with chronic renal failure and 87% of cats with hyperthyroidism have high blood pressure, according to research (citation below).

For Kitty, we took a blood sample to test for kidney disease and hyperthyroid disease. We discovered that Kitty did have some mild changes to her kidneys, too. We started blood pressure medication for Kitty, and when she came in to have her pressure rechecked, her owner told us that she was a changed cat! She had significantly improved, and was no longer wobbly or falling off her favorite sleeping spot.

High blood pressure can cause signs that owners can note, but again, most people only recognize that there was a problem after their cat's high blood pressure is being treated. We hear comments like: "Fluffy is so much less cranky!" or "Callie's appetite is so much better!" or "Smokey seems so much less restless and has stopped crying at night!" when people come in for their blood pressure rechecks.

Other symptoms of high blood pressure (besides blindness and retinal detatchment) include:

• Seizures
• Circling/disorientation
• Dilated pupils
• Hemmorrhage (bleeding) of the eye or nose
• Blood and/or protein in the urine
• Abnormal kidneys
• Heart murmur
• Weakness
• Signs of thyroid disease

If you think your cat may have high blood pressure, or if your cat is over the age of 7 years and you would like your cat screened for high blood pressure, you may want to consider participating in a current high blood pressure study that is being run. For more information about the study, visit www.mycatcanhelp.com or read more about it on our blog at "Feline Hypertension: What you need to know!"

J Vet Intern Med. 1990 Mar-Apr;4(2):58-62. Hypertension in cats with chronic renal failure or hyperthyroidism.

Kobayashi DL¹, Peterson ME, Graves TK, Lesser M, Nichols CE.