by Jennifer L Dayton

Horses walking into small, confined boxes on wheels can be a scary thing. Depending on previous experience, it can be either more or less scary. As a responsible horse owner, this is an important thing to teach your horse to do well, and to do it confidently and happily.

I believe all horses should learn this, although it is a much more significant part of the schooling of a competitive horse.

In general, whether the trailer is an angle-haul, straight-load, step-up, or ramp, a horse should follow pleasantly and comfortably behind the handler into any trailer. The horse should fit in the trailer, and not be hitting the ceiling or squished into the partitions.

To begin, most problems I have witnessed with loading have a lot to do with the horses' response to pressure on the halter. Body language is also important to recognize, as it is the horses' way of communicating with you. Some horses are terrified; some horses just say no, and have gotten away with saying no; and others have constant worries - not fitting properly, having had a bad experience, slipping or falling.

(A note to all those who drive a horse trailer: from those of us humans suffering from motion sickness - many of you make us feel ill with your quick turns and rapid accelerating and heavy braking; we have to wonder how many horses suffer the same way, and endure rough rides, knocking them about and challenging their balance constantly... not a good thing for horses to want to go back in the trailer for.

The most common problems encountered with trailering involve: the horse backing up, pulling back rapidly, refusing to move at all, dodging from side to side, or a combination thereof. Again, respect for the parts of the halter will help immensely.

If the handler applies pressure to the headstall of the halter, the horse should move forward. Pressure on the noseband should cause the horse to yield, and pressure on the sides of the halter should catch the side-to-side problems. The main pressure that needs to be responded to in loading is the headstall.

Read more: Horse Training Power Tip: Loading Difficult Horses Into Trailers

Electrolyte problems in the heat are directly proportional to sweat loss, so it makes perfect sense that horses working long periods are at greatest risk. This puts the spotlight on endurance horses.

Equine sweat is a concentrated electrolyte solution. Chloride is the most abundant electrolyte in sweat, followed by sodium, then potassium, with much smaller amounts of calcium and magnesium. The daily requirement for sodium can double with just one hour of low level sweating.

Even at low rates of sweating the horse will lose over a gallon of fluid per hour - and up to 4 gallons per hour with heavy sweating. That's a lot of fluid! The first consequence of this is dehydration. Since sodium lost in the sweat is needed to hold water in the body tissues, drinking water alone is not enough to correct the dehydration. Even mild dehydration has a major impact on the ability to perform.

Electrolyte losses triggered by exercise and sweating can produce a variety of temporary signs which respond to hydration and electrolyte replacement. Normal levels are required for regular heart rhythm, intestinal motility, coordinated movements of involuntary muscles like the diaphragm, skeletal muscle contraction and relaxation and the regulation of nerve firing.

Endurance horses show some typical changes in their blood electrolyte profiles. Low chloride is common. As above, chloride is very high in sweat. They do not have good stores of chloride in the tissues to replace what is lost in sweat. Low potassium is more common than low sodium. This is because horses can pull sodium from the tissues surrounding the body's cells to keep blood levels up. The kidney also conserves sodium by reducing sodium in the urine and replacing it with potassium.

Read more: Electrolyte Problems in Endurance Horses