Ok…here’s a very basic explanation as to why some horses don’t drink at shows or whilst travelling etc…
It is basically because they are prey animals and whilst under the stress of being in a lorry or at a show they are in a more heightened state of stress, therefore their ‘fight or flight’ mechanism kicks in, this is a physiological response which can switch off the thirst response making it seem like they don’t want to drink but they cannot help it unfortunately, hence the old saying ‘you can lead a horse to water’…etc.
However their instinct to forage is still very strong, therefore they will always graze (as this is mother natures way of sustaining them whilst on the move in the wild).
It’s ok tempting them to drink with apple bobbing, syringing or with flavoured water but this is still water and as such they may take some, but not nearly enough fluid in to replenish that which has been lost, this can be in excess of 20ltrs per day if at a multiple day show (especially when their needs have increased by more than 200% with travelling, heat and exertion), some suggestions of flavourings such as apple juice or molasses may also cause an increase in acid production in the stomach which may have a detrimental effect on those already prone to ulcers. Hand grazing is good but you’d have to hand graze for much more than 5 hours to get enough fluid from the grass to replace what has been lost that day.
It must also be said that starch cannot and actually ‘must not’ carry water through to the hindgut as to do so could cause a dietary-induced colic, therefore adding water to a starch ladened mash, i.e one that contains a high level of grain, in a pellets form or whole grain form will ‘not’ add any hydration to the hindgut reservoir; it may also cause an increase in acid production and an increase in blood sugars which may exacerbate existing ulcer issues and cause excitable behaviour.
The hindgut is the ‘only’ store for water, the body cannot store water anywhere else. If the body’s fluid levels rise (hyperhydration) then water has to be excreted if they fall (hypohydration) water must be taken back into the body fluid compartment. Electrolytes are there to change the concentration of each cell in the body to force the horse to source water so by adding large amounts of salt each cell shrinks and therefore in an attempt to regain homeostasis the horse is forced to source water; however if water is not available or they still won’t drink then the horse is like to become more dehydrated as the cells shrink further.
When the horse needs systemic water to replace the water lost in sweat, saliva metabolism etc, the body goes to the hindgut, if the water in the hindgut is low then the body draws fluid from the bloodstream. This causes the blood to thicken and therefore forces the heart to work harder as it has to pump this thickened blood around the body increasing the heart rate making it harder to recover from exercise.
However the water needs to get to the hindgut in the first place, this is where fibre steps in…fibre is the only way to get water to the hindgut, so increasing the surface area of soluble fibre allows more water to be carried through to the hindgut. This soluble fibre can be found in the cell contents of forage, therefore once this soluble fibre is exposed to water molecules then water can attach. These attached molecules are carried further into the digestive system and therefore are able to increase the hindgut reservoir. This allows the horse to replenish his systemic requirements naturally without needing to shrink each cell with excessive salt.
This is the principle of the new concept of Equine Nutritional Hydrotherapy and the basis of all of our products. Fibre is mother natures way of getting fluid to the hindgut, she’s been doing it for over 60 million years so who are we to argue. I hope this explanation helps, as I would like more people to have a better understanding of the physiology of a horses digestive system so that they are more aware of what to use to encourage proper hydration. So please, not only look after your own hydration needs by drinking at least 2 ltrs of water a day, make sure that your horse is hydrated properly too (15-25 litres on a normal day and upwards of 25 litres on hot days) especially during this summer. 😊💦🐴 #hydrationiskey #equinenutritionalhydrotherapy.
Written by Sandra Murphy BSc (Hons) Equine Sports Science
Equine Nutritional Hydrotherapist
Equidiet (UK) Ltd (01/07/2019)