Advanced Fluid Therapy for the Small Animal Patient

Define dehydration

A deficit in total body water

Strictly refers to loss of water but often used clinically to refer to isotonic and hypotonic losses as well

What are sensible, insensible, and pathological losses of water?

Sensible: things we can measure (like urine output)

Insensible: things hard to measure like sweat or in feces

Pathological: vomiting, diarrhea, wounds, into a third space, panting, renal disease

What are the clinical signs of dehydration?

MM dryness, skin tenting, sunken eyes

What are the clinical signs of <5% dehydrated?

None

What are the clinical signs of 5-6% dehydrated?

Subtle loss of skin elasticity

What are the clinical signs of 6-10% dehydrated?

Definite loss of skin elasticity

Eyes possibly sunken in orbits

Possibly dry mucous membranes

What are the clinical signs of 10-12% dehydrated?

Tented skin stands in place

Eyes sunken in orbit

Dry mucous membranes

What are the clinical signs of 12-15% dehydrated?

As for 10-12% but with additional signs of hypovolemic shock progressing to collapse and death

How else can you estimate dehydration?

Factorial approach: measure water content of all losses

PCV/TP: will rise with dehydration

What type of fluid is usually used for dehydration? What is the exception?

Isotonic crystalloids (0.9% NaCl “normal saline,” Ringer’s, Harmann’s)

Except where dramatic abnormalities in sodium concentration are present

What route for fluids in dehydrated patients is usually used?

IV usually but subQ or oral are very useful for mild cases

How fast should you give fluids for dehydration?

Replace over 24 hours and add maintenance and ongoing losses

How fast should you give fluids for shock?

Rapidly

If you recheck a dehydrated patient a day later and they are still dehydrated, what could cause this?

Issues with fluid administration

Incorrect estimation of dehydration

Ongoing losses

Which is more emergent - hyerkalemia or hypokalemia?

Hyperkalemia is an emergency

What are the symptoms of hypokalemia?

Asymptomatic or muscle weakness and PUPD

What causes hypokalemia?

Decreased potassium intake

Translocation (ECF→ICF)

Increased loss

Where is most potassium stored in the body and why is this significant for determining deficit?

It is intracellular so if you can see a decrease in the blood you probably have a large deficit in the body

What kind of fluid doe we use for potassium supplementation?

Usually spike fluids like NaCl or Hatman’s with potassium

How common are sodium abnormalities?

It is quite uncommon

What causes hypernatremia?

Hypotonic fluid loss/salt intoxication

In what diseases is hypernatremia most commonly seen in?

Neurological disease and diabetes insipidus

What causes mild hyponatremia?

Hypertonic volume losses in GI disease

What is the affect of hypoalbuminemia on the body?

Causes general edema because it affects the starlings forces

What causes hypoalbuminemia?

Either decreased production or increased loss such as hepatic disease, protein losing enteropathy/nephropathy, inflammatory effusions

How is hypoalbuminemia treated?

Can’t just supplement - need the animal to produce their own proteins

Can support them with synthetic colloids 20ml/kg/day, albumin, or fresh frozen plasma

What colloids are used?

Hemacel (licensed)

Pentastarch - not used anymore

What is the risk of treating with human serum albumin?

Healthy dogs go into anaphylaxis but sick ones do not - need to do it at the right time but also not wait too long

What are the drawbacks of using fresh frozen plasma?

Expensive

Not that much albumin in it

Low vascular persistence

Are acid/base and electrolyte disturbances more common with acute or chronic diarrhea?

Chronic

What type of fluid is recommended for diarrhea?

balanced electrolyte solution such as Hartmann’s - may require potassium supplementation

What should be ruled out if hyperkalemia and hyponatremia are present?

Hypoadrenocorticism

What electrolytes are affected by pre-pyloric vomiting?

Loss of K+, Na+, Cl- → hypochloremic metabolic alkalosis

What kind of fluid would you want to use for this?

Acidifying fluid with a high chloride concentration

What is the affect of metabolic alkalosis on the urine?

Paradoxical aciduria

Metabolic alkalosis is self-perpetuating because the kidneys reabsorb NaHCO2 in the presence of volume, chloride, potassium depletion

What kind of fluid is used for pancreatitis?

Choose based on the degree of shock and dehydration but commonly use Hartmann’s and in severe cases may use fresh frozen plasma

What usually needs to be done to stabilize a FB patient prior to anesthesia?

Correct fluid/electrolyte abnormalities

Can have marked loss of fluid and electrolytes into the intestine

If barcarbonate is lost can have metabolic acidosis

In severe cases of hepatic disfunction which fluid should not be used?

Harmann’s because it contains lactate which is metabolized by the liver

What electrolyte and acid/base problems can come with liver disease?

Hypoalbuminemia

Coagulopathy

Hypokalemia

Variable acid/base changes

Hypoglycemia

Ascites

If you only need maintenance fluids for a patient (patients with no deficit or ongoing loss) what electrolyte needs are different?

Need less Na and more K

Glucose is usually added to make them isotonic and prevent hemolysis

What conditions make patients most prone to volume overload?

Renal disease

Cardiac disease

Hypoalbuminemia

Pulmonary contusions

What are the symptoms of volume overload?

Chemosis, serous nasal discharge, increased respiratory rate/effort/noise, restlessness, peripheral edema, polyuria

What are the possible complications of fluid therapy?

Iatrogenic electrolyte disturbances

Volume overload

Catheter related issues

Complications with individual products (such as coagulopathy with colloids)