Blood pressure measurement in cats

Hypertension is a recognised condition in cats that has some potentially devastating effects if left undiagnosed or untreated. The consequences can be significant, with damage to the kidneys, eyes, brain and heart being common and often irreversible.

Posted: 14 May 2018

Blood pressure measurement in cats

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The common recurring conditions we see associated with high blood pressure are chronic renal failure (CRF) and hyperthyroidism. As part of our monitoring of all older patients (cats over 7 years of age) we should be checking for both conditions by using our clinical judgment and diagnostic facilities and tests.

It’s now recognised that a resting repeatable systolic blood pressure greater than 160mmHg should be treated as abnormal. Regular monitoring of all our ‘at risk’ patients should become routine.

After the initial set up costs to acquire a reliable Doppler machine, the only ongoing cost is some time to train your nurses and vets.

Using some client education both within the consulting room and via newsletters, you’ll be monitoring blood pressures in no time at all.

Common signs of hypertension

  • Weight loss – clients at home may miss this in the early stages, but with regular weight checks at the surgery, these subtle changes can be easily detected.
  • Changes in appetite – hyperthyroid cats usually start to eat more, whilst cats with CRF will usually eat less.
  • Sudden dramatic loss of eyesight – hypertensive cats are at a significant risk of retinal bleeds and retinal detachment. As many as 50% of hypertensive cats develop hypertensive ocular changes, with some changes occurring with a BP of just 160mmHg. They can often go blind overnight with an obvious red filling of the eye. Owners may also notice pupillary dilation.
  • Depression – many cats with secondary hypertension will be clinically affected by their primary condition. Both CRF and hyperthyroidism may cause lethargy, weakness and depression.
  • Neurological signs – cerebral oedema, arteriosclerosis and bleeding within the CNS may have a dramatic effect on mobility and proprioception. Seizures, ataxia, depression, vestibular signs and coma can occur.
  • Heart failure – vascular resistance and hypertension often result in increased cardiac muscle hypertrophy (left ventricular wall hypertrophy). Affected cats will usually go on to develop gallop rhythms and murmurs. Heart failure with all the associated signs can then develop.

Which cats should you be monitoring?

Age of cat

Hypertension is much more common in older cats. Ideally, any cat over the age of 10 years should be considered and checked.

Under 7 years of age                  Check BP every 12 months

Healthy cats 7-10 years               Check BP at least every 12 months

Healthy cats over 10 years           Check BP every 6-12 months

Pre-existing conditions

There are a number of medical conditions or signs that would normally raise alarm bells regarding hypertension. These cats should be checked immediately and have their BP monitored every 3-6 months.

  • Chronic Kidney Disease
  • Hyperthyroidism
  • Cushing’s disease
  • Neurological disease
  • Ocular changes
  • Unplanned Weight loss

16 tips to reliably measure feline blood pressure

  1. Doppler works best – for a conscious cat in a veterinary practice, using Doppler will be more reliable, accurate and consistent.
  2. Use a quiet room – always find a room away from the hustle and bustle of the rest of the practice. You want your patient to be relaxed and calm. There’s little point in using a busy consulting room next to a waiting room full of barking dogs.
  3. Comfort – let the cat rest on it’s own bedding with its own scent. This will be less stressful.
  4. Don’t rush – if you give yourself just 5 minutes you’re going too fast and will be under too much pressure. Allow a good 15 minutes and take your time. It also helps if you let your cat have a few minutes to settle down and get used to the room and people first. If you rush at it your patient will be anxious.
  5. Let the cat explore – if a cat is brought into a room that is unfamiliar, it is likely to be unsettled and stressed. Why not allow the cat to explore the room first, sniffing and checking all corners to reassure itself that there is no threat?
  6. Training helps – when it comes to measuring blood pressure, the best clinicians are usually calm and have had good training. If you’re just starting, take advice from your colleagues and sit in on their consultations. Watch carefully and take home their top tips.
  7. Practice, practice, practice – there’s a limit to how much you can learn by reading and watching videos. The best way to gain experience and become good is to practice.
  8. Choose the right cuff – it’s vital to use a cuff that fits correctly. A good rule of thumb is that the width of the cuff should be no less than 25% and no more than 50% of the circumference of the limb being used. A cuff that is too large will give unreliably low blood pressure readings and a cuff that is too tight will give abnormally high readings. For most cats a 2.5m cuff is ideal. Soft cuffs fit better, so choose either latex or soft vinyl. If there is an arrow on the cuff this needs to be aligned with the artery.
  9. Keep the limb at heart level – it’s imperative that the cuff and limb are aligned with the level of the heart. Keeping a cat in lateral or sternal recumbancy works well. Use a soft bed to keep you patient comfortable.
  10. Get good transducer contact – apply spirit over the area to dampen down the fur, and then apply plenty of gel - lots of it massaged into the area a few minutes before starting.
  11. Inflate gently – when pumping air into the cuff, be gentle and puff gradually so as to not frighten or surprise your patient. Inflate to 20mg above the point where blood flow is no longer heard. Any higher and the feeling will become uncomfortable and there is risk of the cat moving.
  12. Release the cuff slowly – as the air is slowly released from the cuff, the systolic blood pressure is at the point where the pulsating blood flow is heard. Release slowly and consistently so as not to startle the cat.
  13. Place the transducer in the right place – if you’re using the front leg, place it over the superficial palmar artery at the arch. Place it over the dorsal pedal artery in the hind limb. It also helps to not hold the transducer too firmly against the artery as this can occlude the vessel.
  14. Stop when moving – if the patient tries to get up and move, or if there are signs that they are getting agitated or unhappy, it’s probably better to stop. If you use firm restraint, the BP will be less relevant.
  15. Take multiple measurements – the first BP reading is usually ignored. Take a further 5 reading, and ensure that the readings are consistent. The BP reading to record would be the average of the 5.
  16. Minimise the variables – when repeat readings are taken in future weeks/months, try to use the same room, equipment and staff each time. This will help you to replicate the conditions as far as possible.

Watch this great Youtube video for practical tips

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