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 old, it should be safe to add another 4gms of bicarb to the 1000 bottle (one 50 ml bottle of 8.4% or 1/3 of the 13gms provided in the small bags of bicarb attached to the bottle). 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:
- Measure each sample three times. Take average.
- 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