Feline systemic hypertension
Why should I measure blood pressure?
Many of the diseases seen in everyday practice can cause high blood pressure:
Renal, hepatic, and cardiac insufficiency
Neoplasia – pheochromocytoma; mineralocorticoid-secreting tumor (primary hyperaldosteronism)
Some of the drugs/nutraceuticals used can cause high blood pressure:
Drugs – phenylpropanolamine (PPA), phenylephrine, theophylline, aminophylline
Supplements – Ma huang (Ephedra sinica)
Many of the clinical signs seen every day could be due to high blood pressure:
Acute blindness (due to retinal hemorrhage/detachment)
Increased tortuosity of retinal vessels
Decreased/ increased appetite
Increased water consumption
High blood pressure can be a "silent killer"
No overt clinical signs may be noticed.
Can be the primary problem – "essential" hypertension – with no underlying cause.
The time to diagnose high blood pressure is before damage is done. Retinal hemorrhages and detachment can be avoided in a well-managed feline patient. I recommend that Doppler ultrasonic blood pressure measurements begin in all patients at an early age as part of their health care program. That helps the veterinarian establish a baseline for each individual cat. Senior cats, which have a greater risk of developing diseases that cause high blood pressure, should have their blood pressure checked every 6 months. Once a cat has been diagnosed with a disease that can cause high blood pressure (ex: Chronic kidney disease), blood pressure measurements should occur at least every 3 months or sooner if any concerns arise. Your clients are well educated about high blood pressure, so it is easy for them to understand the importance of blood pressure control in their cats.
How do I measure blood pressure?
Direct arterial measurement
Impractical for routine monitoring
Useful during procedures performed under anesthesia
Doppler ultrasonic method - preferred method for cats
Blood pressure measurement: Technique tips
May be performed in the exam room with the client or in a separate area.
While we try to perform blood pressure measurements under these ideal situations, there are exceptions to the rule. Some cats are "difficult to handle", but still need to have their blood pressure measured. An accurate blood pressure measurement can be obtained, even on a cat that is trying to "eat you alive".
Cats – tail (median coccygeal artery), fore limb (median artery), rear limb (dorsal metatarsal artery)
Use the "up" leg
Width of the cuff should be 40% of the circumference of the measurement site (tail, leg)
Cuff too small or too loose – falsely elevates the readings
Cuff too large or too tight – falsely lowers the readings
Obtain a series of 3-5 readings, with at least 30 seconds between readings to allow recirculation
Doppler Probe - use alcohol to separate the hair and apply gel to pick up signal.
Blood pressure measurements – Normal systolic reading
Goal: Less than or equal to 145 mmHg
How do I manage high blood pressure?
Drug therapy – may require single or multiple drug regimen
Calcium channel-blocking agents
Amlodipine (Norvasc) 0.625 – 1.25 mg/cat/day PO
Diltiazem 0.5-2.5 mg/kg PO q.8h; sustained release (Cardizem CD) 10 mg/kg PO q.24h
Angiotensin-converting enzyme (ACE) inhibitors
Enalapril 0.25 - 0.5 mg/kg PO q.12-24h
Benazapril 0.25-0.5 mg/kg PO q.12-24h
Atenolol 6.25 – 12.5 mg PO q. 12-24h
Furosemide 1-2 mg/kg PO q.12h
Spironolactone 1-2 mg/kg PO q.12h
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