With the decision to do a 100 mile ride, I have been doing a whole lot of serious thinking, planning and research on all aspects of endurance riding and care in order to find some unknown holes in our regimen and make changes as soon as possible.
One topic that comes up pretty often is that of electrolytes.
The dosage of electrolytes comes up in two forms and my brain tends to work in a fairly common sense, simplistic manner when looking at these things.
Type 1: replacement during exertion. This makes 100% perfect physiologic sense to my brain. As the horse is working they produce sweat and in that sweat is water and electrolytes. Since you are continuing to ask for exertion without allowing adequate time to refuel and reload to a state of balance once again, dosing electrolytes throughout the race becomes very important. Some horses require more than others and this will vary with weather and the amount of exertion.
For this I use a syringe versus loose in her feed because then I know for sure that she got it and how much. I have made my own recipe to mix in with mashed carrots or applesauce as well as purchased them and both seemed to have worked the same. I dose the night before, the morning of and during the holds.
I am horrible at doing it during conditioning rides which needs to improve.
Type 2: pre loading during periods of rest. This makes zero physiologic sense to my brain. When the horse is at rest, most often the week leading up to a ride, dosing with electrolytes to enhance drinking and therefore hydration. There is a big contingent of riders who advocate this and I am really scratching my head over it.
Looking at it from a physiologic perspective, the body maintains a state of balance/homeostasis. When this is thrown off kilter in either direction, loss or excess, the body uses its many pathways to correct this and return to a balanced state.
So there is Gem hanging out in her pasture the week up to the ride. She is eating her free choice hay at will, munching on some spring grass, getting her Triple Crown fortified feed and has access to good, clean water at all times. In theory, she should be in a state of balance since animals aren't like us humans and tend to remain hydrated as long as water is available. They don't skip the water for a sugary beverage of pure sweet tea filled delight.
So anyway...I head out there and dose her with a big syringe of electrolytes. My goal in this is to enhance her hydration based on the recommendations of the masses so that she starts the ride in perfect hydrated status. She takes it reluctantly because man is it a gross goop and then I stand back and watch her. She heads to the water tub and drinks deeply. She continues to drink more than the previous day and I leave the barn satisfied that I am improving her hydration status.
Meanwhile, Gem's body has stepped out of homeostasis and is now in a state of imbalance with excess electrolytes flowing through her blood stream. It kicks into overdrive to use the pathways to return once again to its natural balanced state. She intakes more water to help flush the electrolytes out and her kidneys begin pumping away. Eventually, she begins to urinate more and more and she flushes this out of her system and finally returns to a state of balance.
I suppose that if she was mildly depleted of electrolytes, she would absorb and use some of what I gave her, but most of it will have ended up in the pasture soil.
The next day I head back out and see her again. I notice how much water she drank and pat myself on the back for increasing her hydration status so well. I then redose her with more electrolytes and the process begins anew.
In the end she will have drank more water the week leading up to the ride, but it was all excreted promptly along with the excess electrolytes. I also just increased her likelihood of having ulcers from the goop and taxed her system with having to work more to excrete the useless electrolytes that I just pumped into her body needlessly.
Or at least that is how my understanding of physiology understands it.
I do think doing some electrolytes the day before the ride makes a bit of sense just in case she is depleted a bit sitting in her pasture. I wouldn't do it to increase her thirst, but instead to actually replenish any needed electrolytes. What has worked for me is to start her on a slurry of Grand Vite and alfalfa every day the week before a ride to help replenish anything she is needing and to get her body used to alfalfa again. I only ever feed alfalfa during a ride, so I like to give her some leading up to it.
I think I will just continue doing that until someone can better explain why on earth I need to shove salt in my mare for an entire week up to the ride hoping to get her to drink more. I can only imagine how her stomach would be nauseated and how bloated she would feel after doing that.