guest wrote:My wife brought this question home on an employment application and I don't understand it. Please help me understand the question.

"If a dog is sedated with a sedative and the dose is based on weight, compute how many milligrams of sedative are needed for a 32 lb dog. Dosage of sedative is 1mg/ml body weight, strength of solution is 100mg/ml. How many ml's are needed?"

P.S. She is applying for a receptionists position so I'm hoping that they don't expect her to tell the vet the proper dosage.

Thank you for your help. Leon

The information they gave you seems suspect, as 1 mg/ml of body weight doesn't help us here... notice that by this we would be giving 1 mg of medication per ml... but ml is not weight, it's volume, and we don't know the volume of the dog!

If on the other hand, we're supposed to give 1 mg/pound of body weigh, the answer would be obtained this way:

1 mg/lb x 32 lb = 32 mg.

32 mg / 100 mg/ml = 0.32 ml

Going off on another tangent, and assuming that they want their receptionist to be a physics major, you could try to estimate the dogs volume by assuming that the average density of the dog is 1.0 g/ml, (the density of water) and coverting 32 lbs to 14.51 Kg. Since 1 Kg of water is 1 liter, then we have 14.51 liters or 14,510 ml of dog. At 1 mg/ml, we'd need to dispense 14,510 mg of sedative at 100 mg/ml, that would have us dispensing 145.1 ml of sedative.

145.1 ml is 5.1 ounces. Thats a little less than half the size of a can of coke. When the dog sees the vet coming at him with a syringe that big, he'll simply pass out, eliminating the need to give the injection at all.

I think the first answer is probably more realistic.

William J. Knight

Health Physicist

Los Alamos National Labs