Max's House

Calculation of 24-Hour Fluid Requirement at Different Levels of Dehydration

% Dehydration

Rehydration
Needs(a)
(ml/kg/day)
Maintenance
Needs(b)
(ml/kg/day)
Total
Requirement(c)

(ml/kg/day)
Multiplication
Factor (d)
(x Maintenance)
1 10 60 70 1.2
2 20 60 80 1.3
3 30 60 90 1.5
4 40 60 100 1.7
5 50 60 110 1.8
6 60 60 120 2.0
7 70 60 130 2.2
8 80 60 140 2.3
9 90 60 150 2.5
10 100 60 160 2.7
11 110 60 170 2.8
12 120 60 180 3.0

a Fixed relationship of 10 ml/kg/day required for each percentage point of dehydration.
b Average maintenance requirement assuming no additional contemporary losses of fluid. This amount may need to be adjusted upward to account for contemporary losses, such as vomiting, diarrhea, and polyuria.
c Total requirement equals sum of rehydration and maintenance needs.

d Alternative method of calculation of total fluid requirement multiplies this arithmetic factor times the maintenance requirement of 60 ml/kg/day; thus, most dehydrated cats will require two times (moderate or 6 percent dehydration) to three times (severe or 12 percent dehydration) maintenance volume.

Note: Water intake from food and drinking must be taken into consideration while calculating the fluid requirement.  One, 5.5 oz can of cat food that contains 75% moisture contains 143 ml of water.

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