Alkanalizing Diarrhea Calves – 3/5/09 Jim Bennett, DVM



Alkanalizing Diarrhea Calves – 3/5/09 Jim Bennett, DVM

(From Vet Clinics of NA, March 09 and Nov 03)

To determine amount of bicarb needed, calculate base deficit:

Total base deficit = wt(kg) X base deficit in meq/l X 0.6

Diarrhea calves with the following attributes have an estimated deficit in meq/l of:

Standing Strong: 5.2 meq/l

Standing Weak: 7.8

Down: 19.1

Strong Suckle Reflex: 4.2

Weak Suckle Reflex: 11.4

No Suckle Reflex: 21.5

For example, a 40 kg calf with no suckle reflex would require:

40 X 21.5 X 0.6 = 516 mm total defict

In contrast, a similar calf with a strong suckle reflex would require:

40 X 4.2 X 0.6 = 100. 8 mm

The amount be replaced can be calculated either in mm/l of base (bicarbonate) or in meq of Strong Ion Difference. They can be considered as equal. Amounts provided by various solutions are:

Isotonic NAHCO3 (1.3%, or 13gm/L): SID = 155 meq/l, or 155 mm of HCO3/l

Hypertonic NAHCO3( 8.4%) has 1meq of HCO3 per MILLILITER, so 50cc provides 50 meq SID or 50 mm of HCO# ( 155 ml of 8.4% per 1000 ml of sterile water will make an isotonic solution. – so if you only have 8.4% available, give 1ml per mm total base deficit diluted in a total volume of 6.45 ml of solution. – 10 cc per 64.5 cc, 100 cc per 645 cc, etc.)

Another way to increase the amount of bicarb provided is to make a slightly hypertonic solution of bicarb. For calves 1 week of age you may be able to add up to three 50cc bottles, or nearly another full bicarb packet to 1000 ml.

Our first example calf with a total base deficit of 516mm needs 3.3 liters or isotonic bicarb. Our second example calf needs only 0.65 L of isotonic bicarb – so an appropriate range for diarrhea calves we see is probably 1-4 L IV

Hydralyte provides a SID of 75 meq/l so two liters would provide 150 meq of buffer activity – or the same as one L or isotonic bicarb IV.

Note that Hydralyte is a hypertonic solution – so if you get crazy with hypertonic IV therapy and you want to dilute with oral electrolytes, Hydralyte may not be the best choice – it is about double blood osmolality.

Blood pH: Normal > 7.2, acidotic= 7-7.2, severely acidotic>7.0

Using the Cardy pH meter:

1. Measure each sample three times. Take average.

2. Calculate base deficit using following formulas:

Base excess (deficit) based on pH reading of Cardy

-301.158+(39.617 X portable pH meter reading.)

For total amout of base needed (or excess) multiply calculated base deficit times weight in kg times 0.6.

For example: blood pH of 40 Kg calf = 6.9 on Cardy pH meter:

Base deficit - calculated directly from Cardy reading

-301.158+(39.617X6.9)

-301.158+273.357 = 27.801

27.801 X 40 X 0.6 = 667 meQ total needed

If one knew the actual blood pH (instead of Cardy reading) the formula for calculating base deficit – in contrast to the one above for the Cardy pH meter, is

-428.11 + (58.601 X pH)

OR One can calculate the actual pH from the Cardy reading as follows:

Actual blood pH=2.159+(0.676 X portable pH meter reading)

In our example, the Cardy reading of 6.9 is actually:

pH=2.159 + (0.676 X 6.9)

pH=2.159 + 4.664

pH=6.823

So for our 40 Kg calf, using the actual (calculated) pH:

-428.11 + (58.601 X 6.823)

-428.11 + 399.834 = 28.275

28.801 X 40 X 0.6 = 691 total Meq needed

This gives a slightly different result, but essentially clinically equivalent

References for use of Cardy pH meter:

Nappert, G. A comparison of pH determination methods in food animal practice. 2001. Can Vet J, 42:364-367.

Nappert, G. Rapid determaination of Acid-Base Status in Diarrheic and Healthy Calves with the Cardy Twin Waterproof pH Meter. 1997. The Bovine Practitioner, 30:144-145

Naylor, J. Evaluation of the Total Carbon Dioxide Apparatus and pH Meter for the Determination of Acid-Base Status in Diarrheic and Healthy Calves. 1987 Can Vet J, 28: 45-48

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