7% of a horse’s weight is drunk daily – 3 buckets for a 900 lb horse. This merely tops up the horse’s needs; saliva, acid and enzyme secretions and maintaining the moisture level of the gut contents takes 25 gallons of water. If this is not ingested, it is drawn out of the body. During exercise another 4 gallons of water per hour can be lost as sweat! Moisture is also lost through breathing, faeces and urine. Losses can be greater than intake especially if there is little moisture in the feed offered.
This results in dehydration. The water content of the cells and the circulatory system all drop slightly and impacts on the physiology of the animal. Gums look paler, eyes yellower and elasticity of cells is reduced – a pinch on the flank will take a time to disappear. Other symptoms include rapid, shallow breathing (with slower circulation the body is trying to get more oxygen in the blood to compensate), dark yellow urine (cutting down water loss) and, if dehydration continues, a reduction in sweating and salivation. As the body tries to reduce moisture losses, water will be resorbed from the gut and colic may result.
A grazing horse ingests 3 lb of water for every lb of dry material eaten, and is therefore in the region of full hydration. A hay fed animal will only get 2.5 fl oz – about 1/20th the amount of a grazer, and so needs to make this up and can do so by drinking to his limit. However, when activity increases, or the animal is stressed (environmental temperature, travel and strange surroundings or even a change in routine), dehydration occurs and we need to encourage a greater water intake to compensate.
Wet feeding is a route to do this. If we do not have continuous access to lush pasture, or exercise our horses at moderate levels, wet feeding can help as horses may not regulate their water intake solely through drinking. It also benefits digestion and the water balance of the gut if water is integral to the feed rather than an addition.
Soaking hay and compounds helps, but neither have the capacity to hold much water. Products like Speedi-Beet and Fibre-Beet that have been designed to be fed wet have great absorptive capacity (hold a lot of water), but also can release it readily (low water binding capacity) so it can be absorbed. They have both been used in endurance events to aid rehydration during rests.
By using wet feeding, and products specifically designed to be fed wet, water is taken in with the feed as nature intended, and drinking as a top up keeps our horse well hydrated.