If you work with or own horses, then you should know the equine vital signs. In order to determine if something is wrong with your horse, you have to know what is normal for them first.
The normal pulse range, or heart rate, for a horse is between 28-40 beats per minute. Foals will usually have 60-80 beats per minute within the first 24-72 hours of birth. To check your horse's pulse there are three different places: the facial artery, the transverse facial artery, and behind the elbow. I prefer checking my horse's pulse from the facial artery because it is easier for me to feel there, but most people I know prefer checking the pulse behind the elbow.
The normal respiratory rate for a horse is 6-16 breaths per minute. If your horse is breathing raggedly, wheezing, or something similar, then something is probably wrong. The normal temperature for a horse is 99.5-101.5 degrees Fahrenheit. Anything over 102 degrees Fahrenheit is considered a fever, and the vet should be called in that situation. The capillary refill test, where you press your finger against the horse's gums and check the refill time, should take less than 3 seconds.
Another important vital sign to know is the mucous membrane color. The color of the membranes can be seen on the gums, around the eyes, or the vulva for female horses. The membranes should be a bubble gum pink color, anything else is abnormal. For example, if your horse has pale pink membranes, it could mean either anemia, poor perfusion, or vasoconstriction. Anyway, my favorite place to check the mucous membrane color is the gums because it is the easiest to see, at least in my opinion. There are a lot of different reasons that your horse's gums are a different color than bubble gum pink, so I might post a list of possible colors, reasons, and causes just in case. But don't forget that if you suspect a problem, you should call a vet!
One of the most important things to know in an emergency situation where your horse has been injured are the signs of shock. To make things simpler, here's a list:
Rapid, weak pulse
Pale mucous membranes
Very rapid capillary refill test
Knowing what is normal for your horse and what is not in terms of vital signs can be the difference between life and death for your dear four-legged friend, so make sure you know your horse inside and out!