I don't do metric, I don't usually need metric and I find all the different units of measure in the metric system bewildering. I torment people here for posting in metric and I think the Canadian government's adoption of metric measures is a silly affectation. Nonetheless, I now have to calculate something important in metric measures and would appreciate the help of anyone here who can work the system.

I have a 1050lb horse with a wound. I want to inject some Penicillin. The drug instructions are in metric and say 21,000 IU/kg twice daily. OK, in metric the horse weighs about 477 kgs so how many IUs is that? Or, put another way, how many IUs are there to a fluid ounce or pint or other common unit of measure?

Jesus, I feel I should be fueling for Air Canada.

IU are not metric, to my knowledge, but an international standard to facilitate communication of a substance quantity. You should be able to find out the concentration of the specific preparation you're using - ie the number of IU/mL or /100mL etc..

Usually though, while substances like vitamins etc are measured in IU (vit D, E) but drug dosages tend to be in mg/kg - however, I know nothing of the veterinary world and stand to be corrected by someone who does.

Thank you for that,

It does say, under Administration and Dosage,

"Horses 21,000 IU/Kg" which I can calculate back to a number of IUs for 1050lbs but nowhere does it say how many IUs there are in the 250ml bottle. Still horses are big, I don't suppose a bit of variation much matters, I'm thinking to shoot a fluid ounce or so.

The IU's is only half of the information you need. You should find somewhere on the packaging or data sheet the information of how many units are in 1ml (if you were a diabetic example it is likely that your insulin would have 100units per ml).

You should therefore do the following calculation:

21,000 x 447 = 9517,000

9517,000 divided by the number of units per ml = the number of mls to give

With this number of units to be given I would imagine that the medication will probably be somethin like 100,000 ui/ml. If the info is missing from the pack contact the person who gave it to you.

I hope that this helps.

It certainly does help.

The package lists the active ingredient as being 300,000 IU per mL. So, 9,517,000/300,000 suggests about 32 somethings per dose. 32 what? 32ccs seems a huge amount though, of course, the recipient is a large animal.

It's about 1 fl oz.

I hope you're not basing your idea of ccs on the supposed origin of the name of the band 10 cc.

I have no idea of ccs, no perception of them, but if I can get an idea of metric volumes just by using my hand I'm up for that.

That would be 32 mls. It does seem a huge amount to inject, but then I am used to injecting humans where you would usually only give 2-3mls at a time, maybe 5mls occasionally but it would hurt.

I am wondering if you have been told the correct doseage.

I know that horses are larger than humans, but not 10 times larger.

This horse weighs about 7 times an average person, so it sounds about right to me.

It is still a large quantity to be putting into dense muscle tissue.

Are you sure that it doesn't say 21000iu/kg daily given over 2 doses? That would be getting a bit closer. (I still wouldnt want to be the one giving the jab though)

21000 of body weight intramuscularly twice daily, it says. Based on this thread I'm going to go with 30ccs twice tomorrow and see what happens.

Thanks everyone.

Good luck, let us know how it goes. Don't stand near the end that kicks

Is there a valid reason why you just don't pay a qualified veterinarian to do this?
By the time all this has been debated, the poor animal could bleed to death!

Hardly in the league of empty fuel tanks on planes or sick horses, but I've missed a car service because the guy I told "it says 6,700 miles at the moment" to thought that was about 2,000km Have I found the only Canadian who doesn't know what a mile is?

With the risk of incurring insults from the anti-metric squad, if the car service guy was under about the age of 35 he was educated completely in metric and would know km/h, km's etc. Living near the US border there is probably more knowledge of the imperial system as well. All of my car service scheduling is done by the km's and the odometer only reads in km's.