Author Topic: Metacam Doses?  (Read 594 times)

Offline MaatAset

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Metacam Doses?
« on: March 03, 2019, 10:15:21 AM »
My boy rat went through hernia surgery on Wed and started removing stitches. Though he didnít exhibit usual signs of pain, I was told to give him the pain meds I had from a previous surgery (from a previous vet) to help reduce inflammation and irritation so it may not bother him as much. I donít recall ever giving my rats more than like .2 of this stuff before and she wants me to give him .4 of the 1.5mL suspension (Iím breaking it in half, twice a day). He makes weird little noises after I give it to him though and it kind of weirds me out. I donít want to be giving him too much. He is a big boy at about 610kg. I need to weigh him to get his exact weight post surgery, but he is about 600kg.

Mostly, I want to know how do I calculate his dosage myself (like seriously dumb it down). And does this dose seem too high for about a 600kg rat?

Offline MaatAset

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Re: Metacam Doses?
« Reply #1 on: March 03, 2019, 10:20:28 AM »
Because we couldnít leave our stitches alone, we got a cone of shame added yesterday. Here we are sitting in the corner of the cage, moping and contemplating how horrible life is and hoping to guilt mom into taking the terrible contraption off.

Offline Michael C

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Re: Metacam Doses?
« Reply #2 on: March 03, 2019, 01:16:39 PM »
I'm not a vet and dosing is complicated and there's some important terminology involved. I'm gonna over-explain for clarity.

MG: This is a unit of measurement for mass. It refers to how how much of the drug is in your medicine.

ML: This is a volume measurement for an amount of liquid.

KG: This is the unit of measurement for your rat's weight. There are 1000 grams (g) in a kilogram (kg) so the conversion is really easy. 600 g = .600 kg.

MG/ML: This is the concentration of medicine within a liquid. It refers to how many milligrams (mg) of medicine are in each milliliter (ml) of liquid. I believe the metacam you're using is 1.5 mg/ml, meaning there are 1.5 milligrams (mass) of medicine in each milliliter (volume) of liquid. Mass is the amount of matter an object contains, while volume is how much space it takes up.

MG/KG: This is the dose. It refers to how much medicine to give your rat based on their weight. The dose refers to how many milligrams of medicine to give your rat per each kilogram of their weight. Being that rats weigh less than a kilogram, it requires some math (or a dosing calculator) to help figure out the fraction. The RatGuide recommends somewhere in the range of .5 to 2 mg/kg for metacam. This means your rat will get .5 to 2 milligrams of the drug for each kilogram of their weight. Sometimes the recommendation is in lbs. instead of kg but you can google a mg/lb to mg/kg calculator to convert the numbers. 

Now we have to use all of these numbers to figure out how much liquid medicine to give. I think of it like sugar in a glass of water. If I mix 1 teaspoon of sugar into a glass of water and I want to consume a total of 1/2 teaspoon of sugar, I'll drink half the glass. If there's only 1/4 teaspoon of sugar in a glass, I'll need to drink two full glasses to get the 1/2 teaspoon of sugar.

Here comes the math part. The calculator linked above will help a lot. To use as an example, let's go with a dose that's exactly in the middle of the RatGuide's recommendations and say 1.25 mg/kg of metacam. We know your rat is about 600 grams or .6 kilograms so for a dose of 1.25 mg/kg, we'd want to give him .75 mg of medicine (1.25 mg/kg x .6 kg = .75 mg) -note; this number is amount of medicine we want to give but the amount of liquid you'll give will be dependent on the concentration of the suspension- If we want to give the rat .75 mg and there are 1.5 mg in each ml of the suspension, we'll give him .5 ml of liquid (.75 mg / 1.5 mg/ml = .5 ml). This is pretty close to what your vet recommended. Doing the math backwards, it looks like your vet is dosing him at 1 mg/kg, which is basically in the middle of what's recommended.

Using the dosing calculator for a 600 gram rat and 1.5 mg/ml metacam, below is a range of doses from weaker to stronger based on RatGuide's recommendations;

.5 mg/kg    = .20 ml (weakest)
.8 mg/kg    = .32 ml
1 mg/kg     = .40 ml
1.3 mg/kg  = .52 ml
1.5 mg/kg  = .60 ml
1.8 mg/kg  = .72 ml
2 mg/kg     = .80 ml (strongest)

tl;dr: Refer to Ratguide and use a dosing calculator.