As horse owners we know tons of details about our four legged friends. We know what treats they like, which buddies they like to be turned out with, what color jumps they’re most afraid of and exactly the spot to curry them to make their nose screw up in that cute pucker face. But one set of facts, that horse owners may not know, could help save your horse’s life! Knowing your horse’s vital signs is a vital (pun intended) piece of information to have. In veterinary medicine we call it the TPR: temperature, pulse and respiration. Being able to gather this information, and knowing what normal is, can help you recognize when something is wrong and is very helpful to your veterinarian when you are calling for advice.
Temperature
While in human medicine they have developed new devices to measure body temperature from various parts (mouth, forehead and ear), in horses we still rely on the time tested favorite… rectal temperature. Because of their hair and variation in moisture on their gums or tongue, other techniques to get the temp (that don’t involve getting that close to the hind legs) have failed. I recommend using a quick-read digital thermometer. The less time you have to spend at the dangerous end of the horse, the better, and they give accurate readings. Old mercury thermometers (you can’t buy them anymore but there are still tons floating around barns out there) take a long time to register an accurate temp (over 2 minutes compared to my 9 second CVS brand digital) and if they accidently break the sharp glass and mercury can be hazardous to the health of you and your horse.
The most important thing to keep in mind when getting a horse’s temperature is SAFETY! Make sure someone experienced is holding the horse, stand close to the horse’s side and let them know where you are (using touch and your voice). Gently lift the tail and insert the lubricated tip of the thermometer into the rectum. It doesn’t have to go very far in, just as far as you’d put one in your mouth (but please remember not to put this one in your mouth). Once you hear the beep, remove the thermometer and take a look at the reading.
Horse’s body temperature runs a bit warmer than people. The average range is between 99.0° and 101.5°F. And while that’s a wide range, most horses stick in a narrow temp range, so if your horse is always 100.8°-101.2°F then a temp of 101.6°F may not be a big change but if he’s always between 99.0°-99.3°F, then maybe 101.5°F is a cause for concern. That’s why it’s important to know YOUR horse’s normal temperature. Also remember that exercise can raise the body temperature enormously; an athletic horse can get up to 104-106F at the end of a hard workout! So if you’ve just dismounted, give your horse 30-60 minutes before checking their temperature for an accurate reading.
Pulse
There are several ways to obtain a horse’s heart rate. The simplest way is to listen to the heart with a stethoscope. The heart sits underneath the 2nd-5th ribs (in the “armpit”) just behind the horse’s elbow. It is situated slightly towards the left and it is easier to hear on the left side, though a proper evaluation of the heart involves listening on both sides. In foals and thin horses, you may be able to feel the heart beat by placing your hand in this space. If not, any stethoscope you can purchase (that does not come out of a child’s play kit or a “naughty nurse” Halloween costume) will be good enough to get an accurate count. Veterinarians invest in high quality stethoscopes to look for other cardiac abnormalities like murmurs, arrhythmias and we can even differentiate between the 4 valves in the heart. Once you hear the heartbeat, give the horse a few seconds to adjust to the procedure. A lot of horses’ heart rates will increase when you first poke their chest with a cold stethoscope. To get a rate in beats per minute (BPM), count the heart rate (each “lub-dub” counts as one beat) for 15 seconds and multiply by 4. This will give you an accurate rate without having to count for a full minute. Veterinarians are very good at their 4 times tables!
Another location you can get a horse’s heart rate is on its head. There are two arteries in the head that are superficial enough and large enough that you can feel a pulse. The first is the Facial artery. This vessel runs along the mandible (jaw bone) under the masseter muscle (the cheek). It is about the size of a pencil and you can feel it by curling your fingers around the mandible and trapping the vessel between your fingers and the bone (it does not have tight attachments in the soft tissue so it will roll around under your fingers a bit). Don’t press too hard or you will collapse the vessel and feel no pulse, but press too lightly and you may not feel a pulse either, so vary your pressure until you feel the beats. The second artery that can sometimes be palpated is the Transverse Facial artery. This runs just behind the lateral canthus (outside corner) of the eye. Placing two fingers lightly behind the eye on level with the pupil and you should feel a pulse. Again, once you have the vessel located, count for 15 seconds and multiply by 4.
The normal heart rate for an adult horse is 32-44 BPM. Very fit horses (young racehorses) may have lower resting heart rates. An increased heart rate may mean a variety of things but among the top differentials are: exercise, stress, pain, fever, and dehydration. A horse’s heart rate can range from 180-240bpm with exercise but should decrease to near 60 within the first 10-20 minutes of rest and back to normal shortly after. A horse with a persistently high heart rate (>60) or a very high heart rate (>80) should be evaluated by a veterinarian.
Respiration
To record a horse’s respiratory rate you need to have a good eye and be a bit patient. Watch the movement of a horse’s rib cage, counting an inhale and exhale as one breath. This is best done at a distance, so your interaction with the horse doesn’t affect his breathing. Feeling the breath coming out of his nostrils seems like the easy answer but most horses will sniff your hand in the process, falsely increasing the number of breaths counted. If you have a stethoscope you can listen over the trachea (the windpipe) on the underside of the neck about half-way from the throat to the chest. Listening to the thorax (chest) of a horse even with a stethoscope does not guarantee hearing lung sounds. Because of the thickness of the horse’s chest wall (skin, ribs, muscle and maybe a little fat) there is a large distance between the bell of your stethoscope and the air in the lungs. Combine that with how slowly horses breathe, many times in a normal adult horse you cannot hear any lung sounds at rest.
A normal resting horse will breathe between 8 and 20 times in a minute. Obviously with exercise there will be an increase and we also see higher respiratory rates in hot and humid weather. If you horse’s respiratory rate is high without recent exercise or if there is any noise heard associated with its breathing, you should contact your veterinarian.
While there are many components to completing a physical examination of a horse, the TPR is the place to start and can provide you and your veterinarian with important information regarding the health of your horse.
*Side Note: If you want to be extra cautious, keeping an equine first aid kit (sometimes referred to as a barn kit) can be extremely useful in precarious situations where a vet visit is not an option.
About the Author: Dr. Joan Norton VMD DACVIM founded Norton Veterinary Consulting and Education Resources to promote equine veterinary education to horse owners, professionals and veterinarians. In addition to education on both general and focused topics, Norton Veterinary Consulting and Education Resources offers case-by-case equine internal medicine consulting to help diagnose and manage challenging or mysterious cases.