Blood pressure monitoring


Blood pressure monitoring in dogs

Q: Dr. Mike My 8 year old JR terrier was diagnosed with grade III/VI systolic murmur recently, and during the exam, her blood pressure was taken. Her systolic pressure was 180. The examining Veterinarian suggested that we have a follow-up reading taken a few weeks later for comparison to see if her pressure was consistently high. I was wondering why blood pressure is not routinely checked in dogs. Wouldn't there be a benefit to this exam? I have noticed that few clinics in my area have the equipment to perform this exam, and wondered why that was. Thanks in advance for any light you might shed on this subject. I haven't seen this discussed anywhere else. Maureen A: Maureen- Blood pressure monitoring in dogs and cats will become more common as time goes on. At present there are some problems with equipment and there does not seem to be a clear consensus on blood pressure normal values. It is harder to measure blood pressure in dogs and cats than it is in humans because of the variances in size, anatomy and willingness to sit still and allow the process to take place. There are three methods for obtaining reasonably accurate blood pressure measurement. The oldest and most accurate is placement of a catheter directly into the artery and direct measurement of the pressure using a manometer. Most vets are not really anxious to place arterial catheters in patients for routine monitoring of blood pressure. Two methods of "indirect" blood pressure measurement are also used. One uses a Doppler system and the other an oscillometric system. The oscillometric system is probably more accurate but doesn't work well for pets weighing less than fifteen pounds making it impractical for use in most cats and many small dogs. It measures both systolic and diastolic pressure. The Doppler system only measures systolic pressure. It can be used in any size patient but is not considered to be as accurate and requires a trained operator. The definition of hypertension varies from reference to reference. Dr. Morgan's "Handbook of Small Animal Practice" lists the range for normal arterial blood pressure as 130 to 180 for systolic pressure and 60 to 100 for diastolic pressure and makes no distinction between dogs and cats. I have seen references that suggest that anything over 120 may be hypertension in the cat and that the high end of normal systolic pressure in the dog may be as high as 210. Blood pressure is known to vary among breeds of dogs and that may explain some of the reported differences. Blood pressure devices cost between $900 and $3500 new. It is possible to buy oscillometric units used from the human market and modify the cuffs for pets but the savings aren't all that great after doing that and the machines are more sensitive to the human blood pressure ranges which are lower than those of pets making them a little more inaccurate for vets. To be able to monitor blood pressure with reasonable accuracy the cuffs must be correctly sized. One of the problems with veterinary medicine is that this cost must be recovered in some manner and the office visit price is usually competitive in veterinary medicine so that isn't a good place to make it up. But people are used to having their blood pressure taken as part of an office visit at their doctor's so a separate charge can be hard to justify, too. So vets are buying one or two machines that are probably not going to be money makers and for which the accuracy is a little questionable and normal values hard to find. Many vets, looking at all of this, opt not to buy the machines. I have to admit at this point that I am one of the vets who has opted not buy a blood pressure monitor. It is next on my list of equipment to purchase but I keep hoping that someone will come out with a machine that works easily in cats and larger dogs and has less room for operator error. With all of that said, I think your vet should be commended for taking a progressive course and at least trying to monitor blood pressure. Unless some of us do that and pioneer the effort there never will be more accurate information and better machines.


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...