By Dr Kate Martin BSc (Hons.) BVMS MRCVS, Senior Veterinary Consultant & Product Research Manager for eVetDrug Ltd.
Dehydration and electrolyte imbalances have serious physical effects on any horse and can play a significant role in a horse’s recovery and performance. They can lead to fatigue, muscle damage, laminitis, azoturia (tying up), gastrointestinal issues or they can simply lead to a loss in performance; in fact, dehydration is understood to be the most common cause of under-performance and is said to be like ‘competing with a hangover’.
As a horse sweats, it loses a hypertonic solution of water and vital electrolytes (body salts), including sodium, potassium, magnesium, calcium and chloride. Even a fit horse can produce vast amounts of sweat, as the horse relies on sweating to control body temperature during exercise. If both water and electrolytes are lost and not replaced, the horse will become dehydrated and performance will be affected. Plain water alone dilutes the remaining electrolytes so the kidneys excrete water, in a bid to maintain the right concentration of electrolytes in the kidneys, and the stimulus to drink is suppressed. The horse therefore remains dehydrated and serious electrolyte disturbances can result. As electrolytes are integral to essential cellular functions, such as muscle contraction and transmission of nerve impulses, disturbances can trigger muscle disorders like azoturia. It is, therefore, vital to replace fluids with both water and electrolytes, rather than water alone.
Hydration levels can be monitored using subjective assessment methods like the skin pinch test and capillary refill time (CRT) but it is important to remember that performance can be affected before a skin tent is evident.
In fact, horses are usually 5-10% dehydrated before they show clinical signs of dehydration like a skin tent, tacky gums and a slow CRT.
When should we give horses additional electrolytes and water?
Under normal conditions, an adult horse on a balanced, good quality diet, with access to a salt lick, will receive enough electrolytes; however, there are a number of situations where horses should be given supplementary electrolytes:
- When they sweat profusely or for prolonged periods
- When working hard or when competing
- When the weather is hot or humid
- When travelling for longer than 1 hour, particularly if unaccustomed to it and the weather is warm
- When they are under abnormal stress or during illness, e.g. diarrhoea
If you are unsure whether your horse or your client’s horse needs electrolytes, for a particular situation, it is always better to feed a slight excess and allow the horse to regulate what it needs, as long as the horse is hydrated and water is freely available. If the recommended dose of an appropriate electrolyte source is administered correctly, any excess electrolytes will be eliminated harmlessly. Signs that you may be feeding too many electrolytes could include excessive drinking, an abnormally wet bed and/or loose droppings.
It is impossible for horses to store extra electrolytes for future needs, so daily electrolyte supplementation is usually not necessary unless the horses are on gruelling exercise programmes, sweat excessively or are undergoing a period of abnormal stress. However, ad lib access to sodium chloride, in the form of a salt lick, is recommended and intake should be monitored.
INFORMATION FOR HORSE OWNERS:
The Skin Pinch Test: pinch the skin over the shoulder and monitor how quickly the skin returns to its original position. In a hydrated horse, the skin pings back rapidly; in a dehydrated horse, the fold of skin takes longer than
expected to return to position
Capillary Refill Time Test: press your thumb or finger firmly on the gum and then release it to reveal a blanched area of gum. Monitor the area and time how long it takes for the pressed area to return to a normal colour. Hydrated horses have a CRT of <2secs but dehydrated horses have a slower CRT of 2-4 seconds.
It is important to perform both tests regularly so you get to know what is normal for your horse. Make them part of your regular grooming routine today.
If you are concerned about your horse’s hydration levels, offer them water and electrolytes and cool them down if necessary. If they refuse to drink the water, encourage drinking by adding Horsequencher and give the electrolytes, once they start drinking. If their hydration levels do not improve, seek veterinary advice, as intravenous fluids may be necessary.
To ensure horses maintain good hydration levels, before and after exercise, they should be offered frequent, small drinks and water should never be withheld.
Feeding soaked feedstuffs, such as sugarbeet, and room temperature water, during cooler months, are simple, effective ways of keeping horses hydrated. Adding Horse Quencher to the horse’s water is also a great way of encouraging them to drink, as it is an all-natural mix of grains and flavourings that has been produced specifically to encourage the most stubborn of horses to drink water.
What should we be looking for in supplementary electrolytes?
There is now a vast array of Equine oral electrolyte solutions, powders and pastes on the market and it can be incredibly difficult to work out which is the most suitable. Some formulations contain prebiotics, such as Audevard’s Vetidral, which stimulate electrolyte replacement and absorption, whilst others, like Cavalor’s An Energy Boost, have B vitamins, amino acids and glucose for an instant boost. Every horse and situation should be assessed individually to ensure the most appropriate supplement is given.
Check the label carefully and contact the manufacturer if necessary. Look for chloride combinations, which enable the electrolyte to be quickly and easily absorbed, such as sodium chloride, calcium chloride, and potassium chloride. Avoid products that list sugar, dextrose or corn syrup as the first ingredient, unless your horse is recuperating from illness.
Homemade electrolytes solutions are not recommended as they may do more harm than good and when competing, care must be taken to ensure you are not administering any prohibited substances to the horse.
It is important that powder electrolytes, like Lectade Plus, are reconstituted with the correct amount of water and offered alongside a plain bucket of water. If electrolytes are taken without water, it can actually make the situation worse and
dehydrate the horse further. If powder is added to a horse’s feed, it should be wet and you have to be certain that the horse will finish the ration.
Pastes are generally more expensive per dose but they are incredibly convenient when travelling and competing and can be useful if horses won’t drink electrolytes in their water.
There are also a number of suitable electrolyte maintenance products on the market, such as TRM Isopro 2000 and Nettex electrolyte maintenance, for those horses that do require the additional supplementation, during intense exercise programmes, hot weather or periods of abnormal stress.
If you would like more product information or advice regarding specific electrolyte requirements, for individual horses or yards, give eVet a call today on 01344 283888.