Taking the Heart Rate

TheHorse.Com
by: Doug Byars, DVM, Dipl. ACVIM
January 01 2008, Article # 11076

Horse owners should know how to evaluate the basic health parameters of their animals, including temperature, pulse (heart rate), and respiration, better known by the acronym TPR. They also should know how to evaluate capillary refill time to judge the horse's circulatory health. In this and upcoming Back to Basics articles, we will review these and other basic topics with health care professionals, and we will point you to additional information on TheHorse.com.

This month we sought the experience of Doug Byars, DVM, Dipl. ACVIM (internal medicine), ACVECC (emergency and critical care). Byars began his career at the University of California, Davis, then worked at the University of Georgia before moving to Kentucky, where he spent more than two decades heading up the internal medicine clinic at Hagyard Equine Medical Institute. He now operates Byars Equine Advisory LLC in Georgetown, Ky.

The easiest place to take your horse's heart rate is the mandibular artery located just under the jaw. To take the pulse there you should have control of your horse in a quiet location. Curl the fingers of your hand and place them in the groove between your horse's jaws. Pull your fingers back toward the nearest jawbone (mandible) until you feel a cordlike structure. Press that slightly against the jawbone and you will feel the pulse beating. The pulse is the blood flowing in response from the heart beating.

Count the number of beats in 15 seconds and multiply by four to get the horse's resting heart rate. Resting heart rate in an adult horse is 36-44 beats per minute. The heart rate in a racing horse can exceed 200 beats per minute. Amazing, isn't it?

If you check your horse's pulse regularly to familiarize yourself with how his normal resting heart rate feels, you'll be able to recognize if his heart is pumping harder or less hard than normal.

There are a few other places you can take your horse's pulse or heart rate; the one most frequently checked is the digital pulse, taken on the posterior digital artery on the pastern between the coronary band and the fetlock.

Again with the horse under control and calm, place your hand around the front of the forelimb ankle closest to you with your fingers on the inside and your thumb on the outside. With your thumb you will feel a depression in the ankle, which is the ligamentous groove. There are three structures in that groove. From front to back they are the vein, artery, and nerve. It is the artery you want to use to take the digital pulse.

Remember, all horses have a digital pulse. Some people can't feel it in some horses when it is very cold or the horse is very relaxed. A "bounding" digital pulse is a sign of increased blood flow to the foot and often indicates laminitis is potentially present. If you are familiar with the feel of the pulse in a normal horse, then you will recognize a bounding pulse--you will feel the blood pump harder and firmer against your thumb and fingers.


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