Changes

==Regulation of Water Balance==

==Regulation of Water Balance==

====Water Losses:====

====Water Losses:====

#'''Urine''': Obligatory water loss is the minimal urine output required to eliminate metabolic waste products (including urea and minerals). Diets that provide protein and mineral intake in excess of daily requirements will cause an increase in urine output<ref name="Cizek">Cizek LT. Long-term observations on relationship between food and water ingestion in the dog. Am J Physiol 1959;197:324-326.</ref>. In contrast to obligatory water loss, free water does not contain additional solutes. Free water loss through urine is regulated by ADH at the level of the renal tubule and the amount of free water lost each day will depend on water intake, total body water needs, and health status.  

#'''Urine''': Obligatory water loss is the minimal urine output required to eliminate metabolic waste products (including [[urea]] and minerals). Diets that provide protein and mineral intake in excess of daily requirements will cause an increase in urine output<ref name="Cizek">Cizek LT. Long-term observations on relationship between food and water ingestion in the dog. Am J Physiol 1959;197:324-326.</ref>. In contrast to obligatory water loss, free water does not contain additional solutes. Free water loss through urine is regulated by ADH at the level of the renal tubule and the amount of free water lost each day will depend on water intake, total body water needs, and health status.  

#'''Faeces''': Water that enters the gastrointestinal tract (either through diet, voluntary intake, or endogenous secretions) is effectively reabsorbed through both the [[Small Intestine Overview - Anatomy & Physiology|small]] and [[Large Intestine Overview - Anatomy & Physiology|large intestines]]. Compromised function ([[vomiting]], [[diarrhoea]]) can result in excess water loss.

#'''Faeces''': Water that enters the gastrointestinal tract (either through diet, voluntary intake, or endogenous secretions) is effectively reabsorbed through both the [[Small Intestine Overview - Anatomy & Physiology|small]] and [[Large Intestine Overview - Anatomy & Physiology|large intestines]]. Compromised function ([[vomiting]], [[diarrhoea]]) can result in excess water loss.

#'''Respiratory Epithelium''': Respiratory water loss will fluctuate depending on ambient temperature, humidity, and activity. At higher temperatures dogs will increase respiratory rate by 12-20 times and cats by 4.5 times<ref name="Wellman"/> to facilitate cooling, which correlates with an average loss of 469 ml/day for a panting dog versus 41 ml/day for an average cat. Dogs at rest in a thermoneutral environment will have an evaporative loss of <1 ml/kg/hr, while during periods of activity losses can reach up to 7 ml/kg/hr<ref name="Caldwell">Caldwell GT. Studies in water metabolism of the cat. Physiol Zool 1931;4:324-359.</ref>.

#'''Respiratory Epithelium''': Respiratory water loss will fluctuate depending on ambient temperature, humidity, and activity. At higher temperatures dogs will increase respiratory rate by 12-20 times and cats by 4.5 times<ref name="Wellman"/> to facilitate cooling, which correlates with an average loss of 469 ml/day for a panting dog versus 41 ml/day for an average cat. Dogs at rest in a thermoneutral environment will have an evaporative loss of <1 ml/kg/hr, while during periods of activity losses can reach up to 7 ml/kg/hr<ref name="Caldwell">Caldwell GT. Studies in water metabolism of the cat. Physiol Zool 1931;4:324-359.</ref>.