Behavior of renin angiotensin aldosterone axis during pulling exercises in euhydrated and dehydrated horses

Current Knowledge of Pathologic Mechanisms and Derived Practical Applications to Prevent Metabolic Disturbances and Exhaustion in the Endurance Horse

“…Consequently, hypochloremic metabolic alkalosis with paradoxic aciduria appears in endurance horses [57]. In addition, a reduction in plasma sodium concentration stimulates the release of aldosterone, with increased absorption of sodium in kidneys and gastrointestinal tract, at the expense of potassium and hydrogen ions, contributing to the alkalosis [10][11][12][13]58]. Furthermore, increased alveolar ventilation for heat dissipation results in respiratory alkalosis [1].…”

“…Plasma potassium concentrations also decrease because of metabolic alkalosis, which drives potassium into the cells and a physiologic reentry into the intracellular compartment on cessation of exercise [9,61]. In addition, as presented before, increased aldosterone concentrations promote hypokalemia [49,58]. These changes, although happen in most of endurance horses in long rides, are more pronounced in those that develop exhaustion and metabolic problems [10][11][12][13].…”

Assessing the impact of draught load pulling on welfare in equids

“…Biochemical indicators such as blood lactate ( 38 , 39 , 49 , 62 , 72 , 73 ), blood oxygen, blood carbon dioxide level ( 42 , 59 ), blood glucose ( 42 , 60 , 62 , 64 , 73 ), and adenosine tri phosphate has been investigated in relation to load pulling ( 59 , 60 ). Moreover, sodium, chloride, potassium ( 61 , 64 ), plasma protein ( 61 , 64 , 74 ), uric acid, urea ( 61 , 62 , 64 , 73 ), plasma triacylglycerols, free fatty acids, and cholesterol ( 60 , 62 , 73 ) have also been investigated in relation to load pulling capabilities of equids. However, these studies have used different parameters in different conditions and the number of studies is insufficient for each parameter to provide a comprehensive understanding of the effect of draught load on the biochemical parameters and quantification of draught load pulling abilities of equids.…”

“…In contrast, in another study, pulling exercise caused a short-term elevation in sodium and chloride, which rapidly returned to resting values within 15 min in horses ( 61 ). During exercise and recovery, the renin-angiotensin-aldosterone axis (RAA) is linked to the acute and chronic defense of blood pressure, plasma volume, along with fluid and electrolyte balance ( 74–76 ). Furthermore, acute hypovolemic stress activates the RAA axis ( 74 ), and high aldosterone and arginine vasopressin concentrations are associated with exercise in horses ( 75 , 76 ).…”

“…During exercise and recovery, the renin-angiotensin-aldosterone axis (RAA) is linked to the acute and chronic defense of blood pressure, plasma volume, along with fluid and electrolyte balance ( 74–76 ). Furthermore, acute hypovolemic stress activates the RAA axis ( 74 ), and high aldosterone and arginine vasopressin concentrations are associated with exercise in horses ( 75 , 76 ). Exercise has little effect on renin levels, although it does increase aldosterone and arginine vasopressin levels ( 74 ).…”