Fluid Therapy

What % of BW is blood volume?

8%

What % of BW is total body water?

60%

How do you calculate the fluid deficit/volume needed?

%dehydration + maintenance + ongoing losses

What is dehydration?

Loss of total body water

What is hypovolemia?

Decrease in circulatory volume

T/F an animal can be dehydrated but not hypovolemic?

True

How can an animal maintain circulatory volume?

Pull water from interstitial space

What level of mild dehydration is not clinically appreciable?

<5%

What are some clinical findings of dehydration?

Tachycardia, reduced jug fill, cold extremities, tacky mm, sunken eyes

Reduction in body weight (very helpful)

Wat are some lab estimates of dehydration?

PCV/TP

Creatinine (if renal function is normal)

What are some causes of elevated PCV/TP that are not dehydration?

Splenic contraction or anemia

Protein loss

High globulin with chronic disease

What USG in adult horses is dehydrated?

>1.030

What USG in young foals is dehydration?

>1.005

What blood lactate levels indicate dehydration?

>2

Why can blood lactate be elevvated?

Due to anaerobic metabolism because of anemia, pneumonia, hypovolemia & dehydration causing poor perfusion

What is maintenance fluids?

60mL/kg/day (can adjust to per hour or per minute if wanted)

Why can giving fluids be challenging in large animals?

Catheters are positional so if in wrong position fluids wont flow

What is maintenance for neonatal foals?

80-120 mL/kg/day

What are some ongoing losses of fluids?

nasogastric reflux (easy to measure)

Diarrhea (hard to measure)

Third spacing

Hemorrhage

How can you give fluids?

IV or oral

SQ is not used

When are IV fluids indicated?

Severe dehydration, refluxing horse, or large volumes

When are oral fluids used via nasogastric tube?

Large colon impactions and it is the least expensive option

If you have an elevated anion gap, what is the most common reason why?

Elevated lactate (lactate is not usually measured by itself)

How do you give a bolus of fluids for very dehydrated animals?

10-20mL/kg at presentation (want about 50 L total over time)

Reassess patient

When are oral fluids not indicated?

large volumes or animals in shock

What determines what type of fluid to give?

Replacement or maintenance?

Electrolyte and acid-base

What are the traits of LRS?

Alkalinizing (lactate anion is metabolized to HCO3 in liver)

What are the traits of 0.9% NaCl?

Acidifying (high Cl content)

What are the traits of plasmalyte A?

Alkalinizing (acetate anion is metabolized to HCO3 in plasma)

What are the traits of 0.45% NaCl?

Acidifying but hypotonic

Can add 2.5% dextrose to make isotonic

What is 0.45% NaCl used?

Patients that become hypernatremic on IV fluids (foals)

What are the colloid fluid types?

LRS

0.9% NaCl

Plasmalyte A

0.45 NaCl

What are the traits of 5% dextrose?

Isotonic, but only has dextrose

What are the traits of 5% or 8.4% NaHCO3?

Commercially available but very hypertonic and will irritate vessels

Dilutes to 1.3% to be isotonic

T/F lactic acidosis is common in dehydrated animals?

True

What fluids to do you if a dehydrated animal has lactic acidosis?

LRS as long as liver is functional

If no longer dehydrated and still metabolic acidosis we give NaHCO3

What fluids to foals need?

Fluid restricted formula because in euvolemic foals they adjust poorly and can cause brain edema

If both HCO3 and PCO2 change in the same way what do you know?

It is simple with compensation

What are the rules for treating metabolic acidosis with fluids?

Correct dehydration and then reassess

Give HCO3 after volume expansion

Why do you not give 5% dextrose during metabolic acidosis?

Would worsen Na, Cl, and Ca

What two fluids can you give during metabolic acidosis initially?

LRS or plasmalyte A

What electrolyte changes are common with colitis?

Hyponatremia and hypochloremia

What electrolyte problems are common with GI disease?

Hypocalcemia

How much TBW is ICF?

66%

How much TBW is ECF?

33%

How much BW is interstitial fluids?

12%

How much body weight is blood?

8%