Know what's normal, so you can tell if something's wrong.

Pulse

The normal pulse for an adult horse at rest is between 26-40 beats per minute. You can feel the horse's pulse easily by placing your hand under the horse's jaw. You can also take the pulse by feeling behind the left elbow, or by putting your ear there, or by feeling behind the horse's fetlock, at the widest part. Foals have rates between 70-90 beats per minute. More than 60 beats per minute in an adult horse at rest is definitely abnormal. Rates over 80 mean something is REALLY wrong. Heart rates over 200 have been recorded in horses during extreme exercise. A well-conditioned horse can have a rate over 100 during competition and be perfectly fine. However, after a strenuous effort (like running up a hill) the horse should get a short rest until its heart has slowed to about 70 beats per minute.

Respiration

The respiration rate is the number of inhalations (or exhalations) per minute. When you are taking the horse's respiration rate, remember, DON'T count both. Count either the number of times the horse breathes in, or the number of times it breathes out, not both, or you will have a rate double of what it really is. To measure the horse's respiration rate, stand back and watch it's ribs move. If you have a stethoscope, you can listen to the breaths by placing it over the horse's trachea, located on the underside of the horse's neck. The normal rate is between 8-16 breaths per minute in resting adult horses. Foals have higher rates, and rates will increase with work, stress, or climate changes.

Temperature

When you take your horse's temperature, make sure you use a large animal rectal thermometer. These thermometers are extra thick, so they will be less likely to break if dropped. If you have one with a ring on the end, you can attach a small alligator clip with some nylon or fishing string, so the thermometer can be clipped to the horse's tail when you take it's temperature. This will keep the thermometer from breaking if the horse swishes its tail and knocks it out.
First, shake the thermometer down. Do this by holding the ring end between your finger and thumb. Shake it downward with short, snapping motions. Do this until the mercury is down to about 95 degrees. How low you shake it does not really matter unless the horse's temperature is way below normal. If this is the case, shake it all the way down. Lubricate it with petroleum jelly before inserting it.
To take the horse's temperature, stand on its left side, facing its rear, and set your hip so it is resting against the horse's leg. Grab the tail with your left hand, about six inches from the root. Hold the thermometer in you right hand. Slowly but firmly raise the tail up and to the side, and insert the thermometer. Push it in gently until only about half an inch is sticking out. Then, clip the alligator clamp on the horse's tail hair. Leave the thermometer in for about three minutes. When you remove it, be sure to unclamp the clip first. When you have removed it, wipe it through a few strands of the horse's tail hair to clean it before you read it.

The normal temperature for a horse is 99.5 to 101.4 degrees F (37.5 to 38.5 degrees C). Foals and yearlings may have higher temperatures, especially if they are nervous. Higher humidity or hotter weather may increase a horse's temperature. The temperature may also be slightly higher if the horse has just been ridden. Temperatures are usually a degree or so higher in the afternoon than in the evening, so if you are taking your horse's temperature for several days in a row, try to do it around the same time each day. Horses in new surroundings or around strange people may also have higher temperatures, and the temperature will usually go up a few hours after the horse has eaten. Cold weather or water may lower the horse's temperature.

Gums and Eyelids

These, and other mucous membranes, are good indicators of the animal's overall health. The eyelid, also called conjunctivae, should be pink. Red indicates that the eye is irritated, but if the mouth, too, is red, there may be a serious problem affecting the whole body. If the horse has pink skin around the eyes, he may be more sensitive than horses with dark skin. A horse that is short of red blood cells may have pale gums and conjunctivae. A dark red or purplish-blue color is called cyanosis, and indicates a lack of oxygen in the bloodstream. Yellow membranes are called jaundice or icterus. Yellow usually indicates a liver problem. With some diseases, spots of blood may be seen under the membranes. Any odd coloration may indicate a disease, and a vet should check the horse.
Dry membranes may indicate fever, or may be caused by certain drugs (like those given to control symptoms of heaves). Odd odors in the mouth could indicate an infected tooth or other problem.

Appetite

If you feed the same amounts every day, you will be able to tell if your horse's appetite increases or decreases. Lack of desire to eat usually indicates something's wrong, especially if your horse is normally an eager eater. If your horse eats only a little one day, be sure to watch him over the next few days. If his appetite continues to decrease, there may be something wrong. Check the horse's vital signs for abnormalities. Also, be sure to watch your horse's intake of water. If he stops drinking, or drinks more than normal, something may be wrong. Take note of any changes in your horse's appetite, and be sure to call a vet if something seems wrong.

Behavior

Sudden changes in your horse's behavior could mean he's sick. In this case, you need to know your individual horse. Every horse is different, so what is normal for one horse might be quite strange for another. It is hard to tell if your horse is sick by watching his behavior if you don't know him, and know what is normal for him. Normal really varies from horse to horse. If he's acting strange, is it because something changed? Did you sell his companion? Did the weather change? Or his feed? Maybe your in a new place, or he's with new horses?

Some diseases or disorders can be diagnosed by the horse's behavior or posture. A horse with colic, may, for example, stretch, roll, nip at its sides, act stressed or angry, or sweat alot. A foundered horse will stand with its hind legs up under itself, and its front legs stretched out in front.
Sick horse will assume strange positions or attitudes. They may act cranky, swish their tails, they may act restless, or sleepy. Some horses may have unusual habits, like stretching at feeding time sticking there tongues out. My sister's mare, when she wants food, will nicker, bang on her stall door twice, then stick her front legs out and stretch until her belly nearly touches the ground. Such behaviors may be normal routine for your horse. But if they are accompanied by any other symptoms, they may indicate sickness.

Signs of a Healthy Horse

*Hair is shiny and sleek
*No grass belly can be seen
*Muscles are well fit
*Horse shows signs of interest in surroundings
*Horse acts energetic
*Horse is not too thin or fat
*Normal riding does not produce sweating or heavy breathing
*Horse does not act tender footed and walks normally
*Horse eats all he is given
*The horse has bright eyes, alert ears, and normal vital signs
*The horse does not act tired, sluggish, or lethargic
*The horse has a thick or shiny mane and tail
*The horse has strong hooves that are shaped normally