Ch 4 Fluid Therapy Flashcards
Maintenance fluids for adult cattle
3.5-5%bwt/d for nonlactating = 40-60ml/kg/day
Additional 80-90% milk production in lactating cows
Maintenance fluids for calves/preruminant cattle
80-100ml/kg/day
Don’t exceed 80ml/kg/hr during rehydration
Parameters assoc with 8% dehydration
- 6 second skin tent
2. 4mm eyeball sinking
The 8% rule
Cattle >8% dehydrated likely req. IVFT vs oral or intra-ruminal
Guide for estimating calf dehydration
% dehydration, eyeball recession (mm), skin tent (sec)
0 % - 0mm - 2secs 2% - 1mm - 3 secs 4% - 2mm - 4s 6% - 3mm - 5s 8% - 4mm - 6 s 10% - 6mm - 7secs 12% - 7mm - 8secs 14% - 8mm - 9secs
Most common metabolic derrangements in cattle with GI dz
METABOIC ALKALOSIS
Much more common than metabolic acidosis
Conditions assoc. w development of acidosis in ruminants
- Calf diarrhoea
- Carbohydrate engorgement (V high VFA absorption)
- Choke/dysphagia (salivary loss - rich in bicarb)
- Acute small intestinal obstruction (volvulus)
Conditions usually alkalotic
Abomasal displacement/volvulus
Caecal displacement/torsion
Intussusception
Fluid therapy for metabolic acidosis
Simply restoring extracellular fluid volume is insufficient to rapidly correct acidosis in calves with naturally occurring diarrhoea
Alkalinising agents can be added incl sodium bicarb, or metabolisable bases such as lactate, acetate, gluconate, and citrate
Lactate probably most commonly used (LRS) L-isomer is the only one efficiently metabolised
Properties of citrate
Chelates calcium so can only be used in ORAL rehydration, unsuitable for IV
Properties of gluconate
Used in combination with acetate, ineffective in calves as alkalinising agent
Recommendations for oral fluid therapy in calf scour
Avoid v high bicarb - >70mM - abomasal alkalinisation may encourage growth of enteropathogenic bacteria.
Isotonic electrolyte solutions containing the alkalinising agents acetate or propionate may be more appropriate.
Calculating base replacement required (bicarb?)
BD
BD × 0.3 × BW = Base required
BD - mEq/L
0.3 is a conversion factor (extracellular water or the “bicarbonate space,”)
The base required is expressed as total mEq of base.
Use conversion factor of 0.6 is used for calves - higher % body water
Base deficit calculation example
When acid-base status not measurable, can correct for a base deficit of 10 mEq/L without sig risk.
Eg for 500-kg cow
10mEq L×0.3×500kg=1500mEq
No of mEq of HCO3- in 1g sodium bicarb
12
Therefore in 10mEg base deficit, req 1500mEq base replacement - = 125g bicarb
Since 13 g of sodium bicarb made upto 1 L of water is isotonic solution, it would require just under 10 L of isotonic (1.3%) sodium bicarbonate solution to correct a BD of 10 mEq/L. Therefore about 10 L of isotonic sodium bicarbonate solution, or 125 g of sodium bicarbonate, is needed empirically to treat moderate acidosis in an average-sized cow.
Potassium in acidosis
Becomes extracellular (exchanged for H+) so may be hyperkalaemic, altohugh subsequent urinary excretion can rx in total body deficit
Serious hypokalemia may result when potassium moves from extra to the intracellular compartment while acidosis is being corrected. For this reason, potassium should be included in alkalinising fluids or should follow immediately after correction of acidosis.
A moderate concentration of 10 mEq of K+/L is safe for hyperkalemic acidotic cattle, even at the 20 L/h rate, if it is administered simultaneously with bicarbonate
Summary for fluid therapy for metabolic acidosis
Most common in diarrheic neonatal calves - not common in adults
Bicarbonate is the most efficient IV alkalinising agent, but lactate and acetate are also effective. In acidotic calves, oral electrolyte solutions containing acetate or propionate may be more appropriate alkalinising agents than those containing bicarbonate.
Fluid therapy for normal acid-base or metabolic alkalosis
Much more common in adult cattle
Treated by providing extracellular anions in relative excess to cations (the strong ion theory)
This is accomplished with chloride-rich, potassium-rich solutions
Conditions commonly causing metabolic alkalosis
Vagal indigestion, abomasal displacement or volvulus, traumatic reticulitis, abomasal ulcer disease, peritonitis, renal disease, and almost any condition that results in anorexia and gastrointestinal stasis
Common electrolyte abnormalities with metabolic alkalosis
Hypochloraemia and hypokalaemia
Solutions used for volume replacement in metabolic alkalosis
0.9% NaCl and ringers solution (NOT lactated as alkalinising); normal saline is acidifying
Add potassium chloride to either solution at a rate of 20 to 40 mEq/L.
1 g of potassium chloride contains about 14 mEq of potassium ion.
2 g of potassium chloride/L yields 28 mEq/L
Oral potassium supplementation should be provided as well because safely administering adequate IV potassium replacement is often difficult
Glucose supplementation
5% glucose solution can be administered at a slow IV rate for several days.
It is usually preferable to infuse 2.5% to 5% glucose in 0.45% to 0.9% sodium chloride or other electrolyte solution
Useful for ketosis etc
Calcium supplementation
Advised for all lactating cattle
500 mL of a commercial calcium borogluconate solution may be added to 20 L of solution for IV administration. Alternatively, 10 g of calcium chloride may be substituted
Intra-ruminal fluid recipe
140g NaCl 25g KCl 10g CaCl2 or 500ml 23% Calcium Gluconate 20L Water
Hypertonic saline dose
4-5ml/kg (4ml/kg horse dose)
Need to combine with 20 L of water administered orally
Summary of fluids in metabolic alkalosis
IV fluids should contain approximately 300 to 500 mOsm/L.
The solution should contain sodium (135-155 mEq/L), chloride (150-170 mEq/L), and potassium (10-20 mEq/L).
Lesser concentrations of electrolytes may be included if glucose is added to the solution.
In dairy cows, calcium borogluconate (5-8 g/L) or calcium chloride (0.5 g/L) should be added. Cattle with ketosis, fatty liver, or negative energy balance may benefit by adding 10 to 50 g/L glucose.
Hypertonic-saline (2400 mOs/L) solution administered at a dose of 4 to 5 mL/kg body weight intravenously and accom- panied by intraruminal fluid is an alternative to large-volume IV isotonic fluid therapy.
Intra-ruminal fluid techniques
Frick speculum and ororumen tube
Nasogastric tube
Pump and oesophageal probe
IV catheter sites
Jugular - easiest and best suited to high volumes
Auricular vein - lower volumes, better suited to longer term (upto 96hr) administration
