Water

Water

Did You Know:

• Horses have a phenomenal sense of smell, accomplished via their flehmen response

• They can easily remember locations of water to return to regularly

• They can sense the smell of water underground, from miles away

Water Basics:

• Water is a vital nutrient, known as the first limiting nutrient

• Makes up 66% of the weight in an adult horse, and is the primary component of all bodily fluids

• Horses can only survive roughly 5 days without water

• Horses need 2-3x more water than any other type of feed

• The average horse drinks 5-10 gallons of fresh water each day (this is just for a horse at rest in a moderate climate)

Equine Water Intake Chart:

Body Weight	Minimum	Average	Maximum
900 lbs / 410 kg	3 gal / 13.5 L	4.5 gal / 20 L	6 gal / 27 L
1200 lbs / 545 kg	4 gal / 18 L	6 gal / 27 L	8 gal / 36 L
1500 lbs / 680 kg	5 gal / 22.5 L	8 gal / 36 L	10 gal / 45 L

Water Requirements vary due to:

• A. Health/Physiological State

• B. Temperature

• C. Activity Level

• D. Humidity

• E. Age (growing vs. mature)

• F. Type of Feed

• G. Lactation

• H. Amount and Quality of Feed

Factors that Affect Water Intake — Temperature:

• As temperature rises, so will water intake

• One study showed daily water intake increased by 79% when horses were exercised at high temperatures

• In colder temperatures, horses are inclined to drink less

• This is exacerbated in conditions close to freezing — almost frozen water is much less palatable

Factors that Affect Water Intake — Exercise:

• Higher workload = higher water intake

• Even just moderate work can increase water by 40% above a horse at maintenance (e.g., 5 gallons vs 7.5 gallons)

• Therefore, water should never be withheld

• A common belief is that a "hot" horse should not have water until it is cool — there is no scientific evidence to prove this entirely (small amounts at a time are best)

Factors that Affect Water Intake — Age:

• Foals have a greater water intake to body size ratio than adult horses, because their urine is less concentrated, making fluid losses greater

• Older horses tend not to drink as much in colder weather

• This is likely why they are more prone to impaction colic and dehydration

• In herds, bullying of older horses away from water troughs can also reduce their intake

Factors that Affect Water Intake — Illness/Disease:

• Chronic kidney disease or diarrhea can cause an increase in water loss (which should mean they will drink more)

• Any condition that causes a decrease in feed intake can also decrease water intake (e.g., gastric ulcers)

• Metabolic conditions often encourage excessive drinking (e.g., Cushing's)

Saliva & Stomach Acid Production:

Saliva & Stomach Acid Production:

• A horse provided ad-lib forage will produce roughly 2 buckets full of saliva each day

• Regardless of meal type or feeding schedule, the stomach will produce 2 buckets of stomach acid per day (1.5 litres every hour)

• Source: Kentucky Equine Research

Water Content in Feeds:

• All horse feeds contain some aspect of water

• Stable feeds (hay, grain, processed feeds) contain 10-15% moisture (1-2 L/day — little) (Muhonen, 2008)

• A perennial ryegrass pasture at roughly 80% moisture, eaten by a pregnant mare, nearly met the mare's water intake (Mulhonen, 2008)

• Haylage and silage can supply 25-45% of the water needs in a mature, idle horse — this means intake volume is drastically decreased (Mulhonen, 2008)

• Pasture moisture content declines over the growing season — in spring it may be 80%, dropping to less than 10% by late fall (McMillen et al, 1943)

Offering Water After Exercise:

• DVM Anthony Blikslager (Equus) notes this is actually OK

• MYTH: When cooling a horse from a strenuous workout, special care must be taken to ensure the horse is completely cooled before offering water, as consuming large quantities at once can cause colic

• Consider: horses don't plan their day like we do — they don't know to drink a big amount before work just because it's going to be hot

• Always offer water! The key is small amounts, frequently

• Stomach/intestines do temporarily shut down when blood flow is directed to heart and lungs

• 1-2 L every 20 minutes or so is safe

• Warmer water is less of a shock to the system, but either temperature is safe

Encouraging Drinking:

 It's not uncommon for horses to drink less water than desired for their health. To encourage consumption:

1. Fresh water

2. Maintain water temperature — horses like drinking water that is 10-15°C

When travelling:

1. Bring water from home

2. Filter the water

3. Flavour the water — products at home such as apple cider vinegar, molasses, peppermint candy, beet juice, or commercial additives

4. Provide electrolytes — commercially available as powder water additives or syringes/pastes, or add a small amount of salt

   • ENSURE WATER IS AVAILABLE. ELECTROLYTES CAN FURTHER DEHYDRATE IF NOT