Glossary
Homeostasis.
Direct answer
Homeostasis is the capacity of an organism to hold internal conditions such as body temperature, blood glucose, acidity and salt content within a narrow range while the environment changes. It works through control loops that link sensors, control centres and effector organs correcting continuously.
Homeostasis does not mean stillness. Values oscillate around a set range, and part of that variation follows a daily rhythm. Maintenance also costs energy: under exercise, in heat or during illness the body shifts its priorities. A value outside the expected range is first of all a sign of regulation at work.
In the horse, water and salt balance is a demanding task, because sweating carries substantial electrolyte losses. The large fermenting hindgut then acts as a reservoir of water and salts. Humans have no comparable buffer, so drinking rules taken from human medicine do not transfer to the horse unexamined.
The evidence letter
Once a month: new syntheses, checked studies, and what has changed in the state of the evidence.