APSC-531-Water

Nutritional Application of Water

Importance of Water for Pets

• Essential but often overlooked in dietary discussions

• Freely available separate from the dietary ration

• Contribution to diet formulation is largely ignored

Functions of Water

General Importance

• Water is the most crucial dietary nutrient

• Acts as a solvent and is chemically neutral

• Serves as a medium for:

  • Dispersion/suspension of colloids and ions in the body

  • Maintaining osmotic balance

  • Digestion, absorption, metabolism, milk/sweat secretion, waste elimination

Transport and Support Functions

• Carries nutrients, metabolites, hormones, and gases

• Acts as a lubricant, supporting organs and the fetus

• Vital for heat exchange and balance due to high thermal conductivity

• Loss of water volume can rapidly transfer heat from the body

Critical Nature of Water

• Second quickest death-causing nutrient after oxygen

• Body can survive loss of fat/protein but only a minor loss of water

Body Composition

• Major component of body tissues

  • Approx. 70% of lean adult body is water

  • Many tissues are composed of 70-90% water

  • Intracellular fluid: 40-45%, Extracellular fluid: 20-25%

• Essential for blood function and the transport of oxygen/nutrients

Waste Excretion

• Required for urine and feces elimination

• Gastric emptying studies indicate moisture levels affect digestion rates (e.g., dry food vs. canned food)

Regulation of Water Intake

Loss of Water

• Primary water loss occurs through respiration, urine, and feces

• Thirst correlates directly with body water content and plasma osmolarity

• Drinking may not be stimulated until mild dehydration occurs (0.5-1.0% body water loss)

Intake Influences

• Food amount and nutrient content affect water intake

  • Linear correlation with food intake in dogs

  • Starvation significantly decreases water consumption

  • Overfeeding protein/carbohydrates raises water intake and retention

Dietary Salt Effects

• High salt intake can increase water consumption in dogs up to fourfold

• Conversely, salt restriction can reduce intake by 20%

Drinking after Meals

• Meal consumption stimulates water intake

• Delay in water access post-meal decreases overall intake in dogs

Metabolic Water

Generation of Water

• Produced through metabolism by oxidizing food

• Vital for desert-dwelling animals and migratory birds

Protein Metabolism

• In mammals, metabolic water from protein equals the amount needed to excrete urea

• Birds can gain net water from protein metabolism due to uric acid excretion

Deficiency of Water

Dehydration Signs

• Signs can appear within days with 5% tissue loss

• Severe consequences occur at loss exceeding 10%

• Loss approaching 15% leads to life-threatening conditions

Salt Toxicity

• Chronic water deprivation leads to symptoms similar to salt toxicity

• Dogs can tolerate high salt if water is available

Symptoms of Water Deficiency

• Initial signs include loss of skin elasticity

• Blood volume maintenance begins at the cost of intracellular water

• Increased resorption of water from urine/feces

• Decreased saliva production and appetite

Complications of Severe Dehydration

• Impaired circulation leads to vital organ dysfunction

• May result in multiple organ failures and death

Requirements of Dogs

Maintenance Needs

• Water needs met via:

  • Voluntary consumption

  • Water in food

  • Metabolic water from nutrient oxidation

• Approx. 50-60 ml/kg body weight recommended per day

Calculation Examples

• 10-kg dog requires 500-600 ml daily accounting for losses

• Daily water needs are 1:1 ratio with energy intake (kcal)

Factors Affecting Water Intake

• Types of food greatly influence water availability

  • Dry food: 8-10% moisture

  • Canned food: over 75% moisture

Life Stage Requirements

• Increased needs during growth, gestation, and lactation

• Data coverage is inadequate for these life stages

• Requirements vary based on work performed and stress

Requirements of Cats

Water Intake Capacity

• Better adapted for periods of water scarcity than dogs

• Greater concentration ability allows for better urine regulation

Calculating Needs

• Similar calculations to dogs may overestimate needs

• Individual consumption can vary significantly

Recommended Practices

• Animals should self-regulate water intake unless dehydrated

• Providing fresh water on a free-choice basis is preferred

Water Consumption Rule

• Suggested intake: 0.5-1 ounce of water per pound of body weight daily

Toxicity Risks

Symptoms of Overconsumption

• Excessive drinking may happen post-dehydration or intense exercise

• Rapid rehydration can disrupt cells, particularly in the brain

• Signs include ataxia, restlessness, seizures, and coma

Water Loss

Pathways of Loss

• Major loss through respiration, urine, and feces

• Dogs do not sweat significantly; panting cools them

Increased Loss During Exercise

• Water loss may increase 10-20 times during intense activities

• Sled dogs experience high urinary loss; diet composition affects solute load

Managing Water During Workouts

• Regular water access helps prevent dehydration

• Cool water enhances palatability and cooling effects

Glycogen Repletion After Exercise

Feeding Strategies

• Diets formulated to spare glycogen provide better performance than those aimed at loading

• Timing and nutrient composition are vital for recovery

Muscle Concerns with Sled Dogs

Performance Metrics

• Tracking muscle concentrations shows differences based on recovery methods (water or glucose polymer)

Blood Glucose Levels Post-Exercise

Impact of Nutritional Support

• Measurement changes in glucose levels show effectiveness of supplementation post-exercise

Conclusion

Vital Takeaways

• Understand the crucial role of water in nutrition for both pets and how it impacts health

• Monitor water intake based on dietary composition, activity level, and species requirements

• Adapt hydration strategies according to environmental and individual needs.