Water As A Nutrient
Water As A Nutrient
Most of us tend to take water for granted. We offer water to our horses, but give little though as to what it really does in our pet's body. Without water; nutrients would not be transported to the cells, waste could not be removed, the horse could not see or hear, or regulate body temperature. Water is the primary component of all body fluids, and without it the horse could live only a few days.
Water can be found in all parts of the body, such as the bone, teeth, ligaments and tendons, where it is joined with other elements to form the structure of the body. The wall of the horse's hoof contains 20% water. The cushion of tissue inside the hoof, that absorbs the shock of movement, contains 45% water. Water makes up about 75% of the weight of the adult animals body and as much as 95% in the newborn, where water deposits in the tissues have not yet been replaced by fat.
Water is a solvent in the horse's digestive system. Because of its ability to dissolve many things readily, it is an ideal medium for the transfer of nutrients from food in the digestive system through the blood and on to the cells. The digestive juices are largely water. The blood and lymph which transport the nutrients throughout the body have a large water content also. It seems a waste that, the water you give your horse comes out the other end! But the waste products from the work of the body cells must be removed, for if allowed to concentrate in the cells would cause serious damage to the animal. These end products (usually salts) are filtered out of the blood by the kidneys and eliminated in the watery urine. Water is also lost in swear and breath.
Without water, the horse would be unable to see or hear, since both senses depend on fluid filled membranes. The eye is filled with a liquid through which light is passed, then the image is reflected on the back of the eye, and the "message" is sent to the brain. Water also lubricates and protects the eye from dirt. In the horse's ear is a water filled sack that picks up the vibrations from the ear drum and passes these vibrations on to the nerves, which take the sound "message" to the brain. This water in the ear also helps the animal with it's sense of balance.
The use of water to regulate body temperature is of great importance to the competitive trail and endurance rider. Heat is produced by the body when food nutrients are oxidized in the cells. All the energy that is used up in digestion and utilization of food is finally changed into heat. The muscles are where the greatest amount of heat is produced, the harder the horse works, the more heat the muscles produce. Under normal conditions this heat is used to maintain the normal body temperature. When the air temperature is warm, or the horse is working hard, the horse's body temperature would raise above normal, if it wasn't for the use of water to cool the body.
When the body temperature rises, more blood flows through the capillaries of the skin where some of the heat passes off into the air by radiation. It is this action which causes the flushing of the skin when one becomes heated. If this blood circulation is not sufficient to keep the body temperature normal, sweat is produced, and its evaporation cools the body. Some horses have been known to pant. Panting increases the loss of heat by vaporizing water from the lungs and mouth, and increases the loss of heat by warming the large amount of air breathed in and out. The horse needs more water on hot days to make up for the amounts lost during sweating, and the action of drinking cool water helps to cool the interior of the horse.
The exact water requirements depend on age, weight and activity of the horse. Measurement of the half-life of body water of farm animals has revealed that an amount of water equal to that of the total body water enters and leaves the body in from 5 to 12 days, depending on the species considered. As a general rule of thumb, however, the horse should drink its weight in water every two weeks.
Ideally your horse would have excess to a cool clear stream, but few of us live in ideal situations. Most importantly the water you offer to your horse has to be clean. Water hardness may affect the palatability of a water supply, but horses may be safely given any water which has been tested and found to be pure and safe, regardless of its hardness. Because there is a difference in the taste of water caused by its mineral content, horses moved to another location may refuse different water at first. In this situation water intake should be carefully watched to make sure that there are no signs of dehydration.
One exception where mineral content effects the quality of water for horses is salty water. It is unsuitable for horses, because it changes the electrolyte balance and intercellular pressure in the body, produces a form of dehydration and places a strain on the kidneys. A high fluoride content in water is also harmful to horses.
If the horse doesn't drink enough water, dehydration will result. It can be caused by refusing contaminated or stale water, illness or insufficient water to replace that lost by sweating. Symptoms include drying and tightening of the skin, loss of weight, and drying of mucous membranes and eyes. Dehydration causes the urine to become concentrated and reduced in amount. If the process is not checked, death will result for a loss of 20% of the body weight in fluid is fatal. Normally, about 3% of the body weight in fluid must be lost before dehydration becomes visible. The dehydration test done on endurance and competitive trail rides is usually taken on the horse's neck but can also be done just below the eye. It takes longer for the skin of a dehydrated horse to move back into shape after pinching than does one that is normal.
Simple dehydration should be treated by replacing the lost water. Water is provided and the horse watched to be sure it is drinking. If the horse doesn't drink, water may be administered by a veterinarian using a stomach tube. In more severe cases, and when dehydration is complicated by a mineral or electrolyte imbalance, veterinary care will definitely be required. This may include intravenous fluid replacement and injection therapy.
With water in every cell of the horse, its importance as a nutrient can not be ignored. Fortunately, while water is of vital importance, it is also plentiful and inexpensive. There is no reason why the need for a pure, fresh, constant water supply can not easily be met. To further illustrate the importance of an adequate water supply, a starving animal may lose nearly all of its carbohydrate and fat, half of its body protein and about 40% of its body weight and still live, but the loss of 10% of its water causes serious disorders and the loss of 20% causes death.
c)1988 by Karen Murray. All rights reserved.
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