isfm International Society of Feline Medicine
Practical recommendations
on the measurement of
indirect blood pressure
in cats

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations
Contents
Introduction

Procedures: Background, methods, patient andenvironment considerations
Blood pressure assessment with the Doppler technique
Blood pressure assessment with the HDO technique
Blood pressure assessment forms

ISFM Panel of Authors
Dr Andrew Sparkes (Veterinary Director)
Caroline Blundell
Martha Cannon
Nikki Gaut
Andrea Harvey
Zuzanna Jacmenikova
Sam Taylor
Audra-Lynne Turner
Aga Zoltowska

ISFM would also like to thank Ceva Animal Health for their help making
the development of these recommendations possible

isfmInternational Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations
Introduction

Hypertension is a common clinical problem in cats, most frequently diagnosed in older cats
(above 7-10 years of age), but still often overlooked. In some studies, hypertension has
been diagnosed in more than 5% of apparently healthy older cats.
The majority of hypertensive cats have an underlying disease that predisposes to thecondition, and chronic kidney disease (CKD) is the single most common of these, withstudies suggesting between 20% and 35% of cats with CKD may have hypertension
A diagnosis of hypertension may be suspected when a cat has a predisposing underlying
disease (such as CKD, hyperaldosteronism, hyperthyroidism) or on the basis of clinicalsigns associated with so-called target organ damage (signs present in organs that arerecognised as being susceptible to the effects of systemic hypertension) such as:• Hyphaema• Sudden onset blindness (retinal detachment)• Hypertensive retinopathy• Left ventricular hypertrophy• Neurological signs
Ideally, hypertension should be diagnosed and managed before systemic effects occur, so
blood pressure measurement of at-risk cats (including older cats and those withassociated diseases) is strongly recommended on a routine basis.
It is generally considered that if systolic blood pressure is less than 150-160 mmHg, thenthe risk of target organ damage is mild to minimal, whereas if systolic pressure isconsistently greater than 180 mmHg the risk becomes severe. However, interpretation ofblood pressure measurements should take into account the individual cat, risk factors for
hypertension, and the circumstances under which blood pressure was measured. It is
important to exclude so-called white-coat hypertension (temporary elevations in bloodpressure due to stress) to avoid treating cats unnecessarily, and this is a common andimportant issue in cats.
This booklet provides recommendations from the International Society of Feline Medicineon the practical measurement of blood pressure in conscious cats in order to make thesemeasurements as accurate and reproducible as possible. Four short videos are alsoavailable to accompany these recommendations and illustrate the techniques involved.

isfmInternational Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations

Procedures: Background, methods,
patient and environment considerations

isfm

International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on proceduresfor blood presure assessment

Background
Hypertension (both primary and secondary to other diseases such as chronic kidneydisease - CKD) is a common disorder, especially in older cats, but the evaluation of bloodpressure and the diagnosis andmonitoring of hypertension are complex.
Indirect blood pressure measurement is
the only acceptable method of assessing
blood pressure in conscious cats, but
this is as much an art as a science.
The two commonly used techniques forindirect blood pressure assessment are
the Doppler and oscillometric methods.
In general, the Doppler method has been
regarded as more accurate (more closely
representing true or direct bloodpressure readings) in conscious cats, but
newer generation oscillometric equipment (especially newer high definition oscillometric HDO - machines) also appear to have acceptable accuracy for measuring systolicpressures in conscious cats.
Whether Doppler or oscillometric equipment is used to assessblood pressure, measurement of systolic blood pressure (SBP)in cats is considered adequate for clinical assessment, as
isolated diastolic hypertension appears to be rare. However,
because blood pressure assessment can be affected by somany variables (including the operator, the conditions andenvironment theprocedure is
performed in, theequipment used, theposition of the cat,and the site ofmeasurement) it isimportant to use
standardised protocols to reduce externalvariables as much as possible, but once
mastered, blood pressure measurement can be a
relatively quick procedure in many cats.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on proceduresfor blood presure assessment

Recommended protocols
Systolic blood pressure is labile and will vary considerably both within and between
individuals. Using a standardised protocol (as recommended by the American College of
Veterinary Internal medicine (ACVIM) in their consensus guidelines - JVIM 2007;21:542–
558) will help to reduce the effect of external influences on blood pressure and makemeasurements more clinically reproducible and reliable. These recommendations, adaptedfrom the ACVIM consensus guidelines, are recommended for use in cats:
1. Environment: It is essential to assess bloodpressure in a calm, quiet environment. This should
be away from other animals, with minimal
personnel, with no other procedures occurring at
the same time and with no interruptions. The
choice of room will depend on clinical needs andcircumstances - itmay (for example)
be in a consultation
room, in a procedures room, in a hospital ward or in thehome environment. In some situations it may bepossible to measure blood pressure in a hospitalised
cat while it remains calm andcomfortable in its cage in thehospitalisation ward. However ingeneral blood pressure should be assessed while the cat is awayfrom other animals, never in the same room as a dog, and awayfrom noise, lighting or smells that may contribute to stress. Try tohave the cat resting on bedding which it is used to and whichcontains its own scent. The use of Feliway® in the environment oron the bedding may be valuable.
2. Acclimatisation: A minimum of 5–10 minutes shouldbe allowed in the environment (room) for the cat toacclimatise before blood pressure is measured. The
cat should be free to explore the environment andinteract with people in the room if it chooses to, butshould not be forcibly removed from the carrier. A
carrier with a removable top can allow the cat to stayin the bottom of the carrier, where some may feelsafer.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on proceduresfor blood presure assessment

3. Personnel: The people present in the room during the acclimatisation period shouldbe the same people that will be present during measurement of the blood pressure.
Blood pressure should be measured by a trained individual, and using a veterinary
nurse or technician who is empathetic with cats is often desirable. When measuring
blood pressure in cats seen as outpatients, it is often preferable to have the ownerpresent to reassure the cat in a quiet, gentle way.
4. Restraint: It is vitally important that minimaland gentle restraint is used in order to keep
the cat in a settled, comfortable position. If
the cat becomes agitated during theprocedure, it is better to stop and take abreak to allow the cat to settle down rather
than persist with more active restraint. Where
appropriate, owners may assist withreassurance and gentle restraint of the cat –having comfortable and familiar bedding forthe cat to rest on will be helpful.
5. Positioning the cat: Where possible the cat shouldbe allowed to relax in a comfortable posture – lateral orsternal recumbency, sitting or standing. The cat should
not be restrained in lateral recumbency but if he or shechooses to lie in this position that is fine. It is best to
attempt to keep the cat in the same position
throughout the procedure and to avoid measuring
blood pressure while the cat is moving.
6. Choice and position of cuff: For cats, the correct cuff width is 30–40% of thecircumference of the site where it is being applied (forelimb, hindlimb or tail). An
incorrect size will lead to false elevation (if too small) or false lowering (if too large) of themeasured blood pressure. Blood pressure can bemeasured on any limb or on the tail - the forelimb may beeasier and more reliable for Doppler, and the tail may be
preferable for HDO. Care may also be needed inmanipulating limbs of older arthritic cats in particular. Where
possible, the site of blood pressure measurement should beroughly on the same horizontal plane as the heart. Moreexpensive cuffs are generally better and easier to use thancheaper ones!

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on proceduresfor blood presure assessment

7. Measuring blood pressure: Before measuring blood pressure it may be advisable toinflate and deflate the cuff a few times to get the cat used to the sensation.
Always discard the first SBP measurement andthen record 5–7 consecutive and consistent(<20% variability between readings)
measurements. If there is a consistent
downward (or upward) trend in the individual
SBP readings, further measurements should beundertaken (possibly after giving the cat a break)until consistent readings are achieved. The meanof 5-7 consistent recordings can then be
calculated to give the final SBP. If necessary, theprocedure should be repeated to achieve
consistent individual readings, keeping the catcalm and still, and changing position andplacement of the cuff if necessary. If less than
5-7 readings are available but they all suggest aconsistent blood pressure well within the normal
range, additional measurements may not benecessary (especially if the cat is becoming agitated). However, if there is any doubt
about the validity of the measured SBP, regardless of the number of measurements,
the procedure should be repeated - either
immediately, after a further period of quiet
acclimatisation, or at a later time point.
8. Written records: Careful records should be kept of
all important aspects of the blood pressure
measurement (see example) ... these should include
date, time, environment, people involved, position of
the cat, size of the cuff, site of cuff placement,
equipment used, individual SBP measurements, andcalculated mean SBP.
9. Consistency: Where repeat blood pressure
assessments are being performed over time, for the
purposes of meaningful comparison, it is important to
try to replicate the assessment using the sameequipment, personnel and procedures as far as
possible each time.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations

Blood pressure assessment with the
Doppler technique

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on the use of
Doppler blood pressure monitors

A variety of different Doppler machines are available to measure blood pressure in catsincluding the CAT+ Doppler (Thames Medical), Vet-Dop2 (Vmed Technology), and the 811B Doppler (Parks Medical). These are all used in a similar way andhave been shown to be reliable in measuring blood pressure inconscious cats.
As always when measuring blood pressure, it is important tominimise stress, use a quiet room, keep the cat away from otheranimals and noise, and allow at least 5-10 minutes for
acclimatisation to the environment (see previous section).
In some situations and with a relaxed cat, it may be possible tomeasure blood pressure single-handed. However, in practice, it isoften preferable to have two people so that one can gently holdand reassure the cat.

Where to measure blood pressure
Blood pressure measured with the Doppler technique isusually performed using the forelimb or tail, although ahindlimb can also be used. There is evidence that theforelimb is generally tolerated better and is easier andquicker in most cats.
On the forelimb,
blood flow is
detected (with the
Doppler probe) in thecommon digital artery
between the carpal
and metacarpal pads,
the inflatable cuff
being placed below
the elbow. On the tail, blood flow is detected in thecoccygeal artery (on the ventrum of the tail) and the cuff
is placed around the tail base.

Selecting cuff size
The circumference of the limb or the tail atthe site where the cuff is to be placedshould be measured. The ideal width of
the inflatable cuff used should be 30-40%
of the measured circumference. A cuff
width of around 2.5cm is suitable for mostcats, but the tail/limb circumference
should be measured and recorded foreach cat.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on the use of
Doppler blood pressure monitors

Should you clip the hair?
To detect blood flow in the artery, it is important there is excellent contact between the
Doppler probe and the skin. This is achieved with the use of alcohol to dampen the hairand skin and the use of ultrasound coupling gel (see below). Clipping the hair at the sitewhere the probe is used is not necessary, but some prefer to do this as it can makedetection of blood flow easier. If done, use quiet, gentle, cat-friendly clippers, and allow thecat time to settle down after the hair has been clipped.

Placing the cuff
The cuff, with the inflatable side towards
the skin, should be placed around theforelimb or tail and should fit snugly, but not
be too tight. If the cuff has only a shortinflatable section, make sure this part ispositioned over the artery to be occluded.
The cuff is usually secured in place with a
Velcro fastener - if needed a small piece ofadhesive tape may be used in addition, but
this should never be wrapped around thelimb. The tubing from the cuff is attached tothe sphygmomanometer. Before use,check the cuff for leaks (inflate it, and checkit does not spontaneously deflate).

Prepare the skin and Doppler probe
To ensure good contact between the Doppler probe and the skin,first dampen the hair and skin (at the site theprobe will be applied) with a cotton woolswab soaked in alcohol.
A liberal quantity of ultrasound gel should
then be applied to the hair between the
carpal and metacarpal pads, or the ventrumof the tail, where the probe will be used. The
gel should be massaged in so that the hairand skin becomes completely saturated withgel. A small amount of gel should also be
applied to the Doppler probe.

Use headphones!
Always use headphones - have these plugged in before turning
the unit on to avoid sounds from the Doppler unit disturbing the
cat.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on the use of
Doppler blood pressure monitors

Measuring blood pressure with
the Doppler
The Doppler probe is positioned between the carpal
and metacarpal pads or over the ventrum of the tail,and held with gentle pressure. Excessive pressure(that restricts blood flow) should be avoided, but
gentle pressure is needed to ensure good contact anda good signal.
The position of the probe is carefully adjusted until
pulsatile blood flow can be heard from the common
digital artery (forelimb) or coccygeal artery (tail). If asignal is difficult to detect, applying more ultrasoundgel may be helpful.

Measuring systolic blood pressure (SBP)
Once pulsatile blood flow is detected, the Doppler probe should be gently held in place,
avoiding any movement. The sphygmomanometer is then inflated by gently squeezing thecompressible bulb. Watch the pressure on the dial of the
sphygmomanometer, and inflate to around 20-40 mmHg
above the point where blood flow is no longer heard.
Air is then allowed to slowly bleed from the valve at the backof the sphygmomanometer (usually a trigger- or screw-valve).
The air must be released slowly, and the systolic bloodpressure (SBP) is the reading when return of blood flow is firstdetected (first heard).
The first SBP reading is usually discarded, as the cat needs tobecome accustomed to the procedure. SBP should bemeasured five to seven times subsequently (allowing the cuff
to deflate completely between each and then repeating theprocedure as above).
If the Doppler signal (blood flow) is lost, the probe may need
repositioning. If the cat becomes agitated, stop and allow thecat to relax before starting again. The aim is to get 5-7
readings that are all consistent (<20% variation) and the SBP is taken as the mean of thesereadings. Fewer (3-5) readings can be acceptable, but more readings increase theaccuracy of the data. Sometimes several initial readings may have to be discarded if there
is a consistent drop in SBP (eg. due to initial stress).
All readings, patient and procedure information should be recorded.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations

Blood pressure assessment with the
HDO technique

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on the use of
HDO blood pressure monitors

High definition oscillometry
While Doppler has been used for many years for theindirect measurement of blood pressure in cats, andhas been shown to have acceptable accuracy in a
number of studies, traditional oscillometric units wereregarded as generally unreliable in conscious catswith poor accuracy and sometimes being unable togenerate a valid reading.
The more recent introduction of high definition
oscillometry (such as the VetHDO, S+B medVet) has
overcome many of the problems associated withtraditional oscillometry and in published studies has
been shown to provide an accurate assessment ofsystolic blood pressure in conscious cats.

Advantages and disadvantages
In general the HDO equipment is a little easier to use
than the Doppler. HDO will also provide a measure ofdiastolic (DBP) and mean arterial pressure (MAP) in addition to systolic pressure (SBP) while potentially helpful, DBP and MAP readings may in fact be much less accurate than
SBP with HDO, and isolated diastolichypertension is regarded as rare incats.
Compared with Doppler, HDO is more
expensive to purchase, and also it isstrongly recommended that the HDO
machine is always linked to a PC ortablet computer while measuring bloodpressure. Connecting the HDO to a
PC allows visualisation of therecording, which is important as
movement or other artefacts can leadto false blood pressure readings.
Using the HDO without a PC may give
spurious results without the operator
being aware.
Because patient movement can readilycause false readings, it isrecommended that the cuff be applied
to the tail when using HDO in cats,
and to keep the cat as still as possible.
However, the cuff can also be used on
the limbs if needed.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on the use of
HDO blood pressure monitors

Patient preparation
As with any technique, when measuring bloodpressure it is important to minimise stress. Use aquiet room, keep the cat away from otheranimals and noise, and allow at least 5-10
minutes for acclimatisation to the environment(see earlier section).
In some situations, it may be possible tomeasure blood pressure single-handed.
However, in practice, it is often preferable tohave two people so that one can gently hold andreassure the cat. The HDO machine should belinked to a PC or tablet (via a USB cable or via
Bluetooth, depending on the unit).

Cuff positioning
In general the HDO equipment comes witha single size cuff for cats and so long as it
is well tolerated, this should be used on
the tail, as this is easier and less likely toresult in false readings from movement
artefact. If more than one cuff size isavailable, the circumference of the tail atthe point where the cuff is to be placedshould be measured, and a cuff width
selected that is 30-40% of thatcircumference.
The cuff should be positioned so that thearea where the inflation tube enters the cuff
is placed ventrally on the tail (close to thecoccygeal artery) as this maximises thesensitivity of the HDO. As with Doppler, thecuff should be checked for leaks before
use.
The cuff should be applied snugly aroundthe base of the tail and secured with the
Velcro fastener - it should be tight enoughto stay in place but not so tight as to cause
constriction of the tail. In some cats, oncethe cuff has been placed, they may behappy to curl up or lie in a basket or bed
without any further restraint or interference.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on the use of
HDO blood pressure monitors

Measuring blood pressure
Once the cuff is in place and the cat is comfortable, the machine can be turned on andblood pressure recordings can begin. First check the settings on the machine are correct
though (for example, that the correct cuff sizehas been entered into the machine).
The PC or tablet should also be connected,
and the software loaded to enable computer
recording and display to take place.
When a blood pressure reading is initiated (bypressing the ‘Start’ button on the HDO
machine), the cuff will automatically inflate
and then deflate at a constant speed. The
blood pressure (SBP, MAP and DBP) willsubsequently be shown on the display alongwith the heart rate. This will also be shown on
the PC along with a visual trace.
The first blood pressure reading should bediscarded as the cat acclimatises to the
inflation and deflation of the cuff.
Subsequently, 5-7 further blood pressure
readings should be taken. Additional
measurements should be made if these are
not consistent (<20% variation) or if there is atrend for lower measurements over time (suggesting the cat was stressed).
The mean of 5-7 consistent readings is taken for SBP (and for DBP and MAP). If the cat
becomes restless, agitated or starts moving, take a break, allow the cat to settle, and thenstart again.
In some cats, if they are veryrelaxed and not moving
much, it may also be possible
to use a forelimb to measure
blood pressure, placing thecuff below the elbow.
With each blood pressure
reading, it is important to takenotice of the PC reading andthe curves displayed toassess whether the reading
may have been affected by
movement or other artefact(see below).

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations on the use of
HDO blood pressure monitors

Checking for artefacts with the PC or tablet
When linked to a PC, witheach set of readings fromthe HDO monitor, alongwith storing the data, avisual display is shown of
the deflation of the cuff
(top line) and the pulse
waves detected (bottom
curve).
The top line should bechecked to ensure it
displays a steady constantdeflation of the cuff, andthe pulse waves should
generate a pattern thatapproximates a bell-curve.
If the above criteria
are not met (mostcommonly the pulse
waves will show
significant distortion)
the reading should
be discarded as
movement or someother artefact may
have affected theaccuracy of theblood pressures
recorded.
This step should not
be ignored, as themachine itself willoften not detect
errors associatedwith movement.
All readings should be recorded (along with other patient and procedure information).
Note studies suggest that while the SBP is accurate, the DBP and MAP measured by
HDO may be inaccurate in cats.

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Recommendations

Blood pressure assessment form

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Healthisfm

Blood Pressure Assessment Form

Date

Time

Cat's name

Owner details

Age
Sex
WeightBody Condition Score
Position of the cat

Sitting

Sternal recumbency

Lateral recumbency

Standing

Other (specify):
Position of the cuff:
Right hindlimb

Right forelimb

Tail
Left forelimb

Left hindlimb

Equipment used

Size of cuff

Location (room)

Others present

Performed by
Subjective assessment of stress:

Record of all SBP measurements (mmHg):
1.

3.

5.

7.

9.

2.

4.

6.

8.

10.

Mean SBP (mmHg) Strike through readings that are ignored and take mean of the remaining values

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For videos go to:www.youtube.com/icatcare
and search for 'blood pressure'

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International Society of Feline Medicine(www.icatcare.org/vets)supported by Ceva Animal Health