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60% - 90% of Body Weight in most life forms

2/3 intracellular fluid

1/3 extracellular fluid plasma

lymph

interstitial fluid

gut

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Occurs when fluid loss exceeds intake

sweating vs time

Dehydration (hypohydration) is defined as anexcessive loss of body fluid. It is literally the removalof water from an object, however in physiologicalterms, it entails a deficiency of fluid within an

organism.

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Clinical Signs weak pulse

poor capillary refill

muscular weakness,

tremors depression

weak pulse,staggering

muscle cramps

Treatment IV or oral fluids

and electrolytes

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Weigh animal before and after exercise

1 kg = 1 L loss of 3% of BW = reduce performance

loss of 10% of BW = serious, possibly lifethreatening

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Blood analysis

Packed Cell Volume and total plasma proteins

rise indicates dehydration

if PCV > 50% indicates hazardous fluid loss

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Skin pinch test falls back instantly -

normal 2 - 4 sec - moderate

4 -6 sec - severe Capillary refill press finger on gums

above an upper tooth if it takes longer than 2

seconds for blood toreturn - dehydration

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Salt that dissociates in solution into electricallycharged particles (ions)

cations - positive charge

anions - negative charge

Function in fluid balance, transmission of nerveimpulses, and muscular activity

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Sodium, Potassium, Chlorine

ICF predominate cation is K

ECF predominate cation is Na

determines water distribution betweencompartments

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Sweat is hypertonic

100 mEq Na:30 mEq K: 130 mEq Cl

small amounts of Ca, Mg, and Zn also lost

Electrolyte loss is easily replaced by dietary means ifsweat is sparse or infrequent

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Electrolyte supplementation recommended ifsweating is frequent

also in hot and humid weather

Dietary electrolytes should replace ions lost insweat in correct proportions

water or feed

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Type of hay

legume vs grass

DCAD - dietary cation anion balance

strong and weak cations vs anions

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Cations

Na+

K+

Ca2+

Mg2+

Anions

Cl-

SO42-

lactic acid

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Lehninger, 1993

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Concept of electrolytes as criticalfactors in acid/base balance

Strong ion difference (SID)

sum of all strong cations minus sum of allstrong anions (NA, K, CL, SO4

2-)

anions greater = negative SID = H+ > OH-

cations greater = positive SID = OH- > H+

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Balance of SID is maintained by thedissociation and reassociation of water

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Three independent variables determine thevalue of H+:

SID

Pco2

H increases as Pco2 increases

CO2 acts as an acid

Total concentration of weak acids (plasma proteins)

H increases as weak acids increase

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Long Term

Kidney regulates electrolytes

primarily Na GI tract

absorption of cationsand anions

dependent of needs

Rapid

Lung releasesCO2 (HCO3-)

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DCAD diets

Sodium bicarbonate administration

IV vs GI

effect of other sodium forms

Furosemide