1. Fluid/Electrolyte Balance 60 % body weight is H 2 O –2/3 intracellular fluid –1/3 extracellular fluid plasma lymph electrolyte - salt that dissociates in solution into electrically charged particles called ions –fluid balance –transmission of nerve impulse –muscular activity

2. Electrolyte replacement –sweat hypertonic electrolyte more concentrated in sweat than blood –lose Na and K and Cl –lose small amount of calcium, magnesium, zinc hot weather - supplement in feed or H 2 O –3 parts NaCl –1 part KCl –4-17 gal of H 2 O/daily –add 2 oz (3 tbls) salt/daily

3. Dehydration fluid loss higher than intake –5-10 liters in thoroughbred race –25-30 liters in endurance race losses mostly from ECF (blood) –decreased tissue perfusion –decreased O 2 transport –decreased transport of energy substrates to muscle –elevated HR loss of 3% (15 liter) - decreased performance loss of 10% - serious problems

4. blood sample –PCV 50% at 30 min post - dehydration skin test –back instantly - OK –moderate dehydration - 2-4 sec –severe dehydration - 4-6 sec capillary refill time more than 2 sec - dehydration signs –persistently high HR and RR –weak pulse –poor refill time –muscle tremors –sunken eyeballs –dry mouth –dry feces

5. more severe signs –cardiac arrhythmias –muscle cramps –diaphragmatic flutter –decreased sweating –CNS damage treatment –oral and IV fluids –electrolyte supplement exhaustive disease –depleted substrate and electrolyte balance