Dose Calculation Explained!
HOW MUCH MEDICATION AM I GIVING?
Veterinarians frequently prescribe medication in a liquid suspension to be given using a 1 cc syringe. Your vet decides how often and how many cc's to give your guinea pig based on its weight, the concentration of the drug in the suspension, and the dosage the vet chooses to use.
To figure out the dosage your vet has prescribed, you need three pieces of information:
- Dose in cc - the amount in cubic centimeters to give at one time
(see: Dose Tips)
- Weight in kg - your guinea pig's weight in kilograms (see: Conversion Chart)
- Concentration in mg/ml - the amount of the drug in the liquid suspension in milligrams per milliliter (see: Concentration Tips)
Enter the dose, weight, and concentration to calculate the dosage in mg/kg.
Say you are giving your 1 kilogram guinea pig 0.625 cc of the standard pediatric suspension of trimethoprim sulfa (Bactrim) twice a day.
..... The dose in cc is 0.625 cc of trimethoprim sulfa.
..... The weight of the guinea pig is exactly 1 kilogram (2.2 lbs).
..... The concentration of the suspension is the standard of 48 mg/ml (your vet conveniently wrote it on the label).
Enter these numbers in the calculator above.
WARNING: Draw only one dose at a time! NEVER draw multiple doses into one syringe and attempt to treat multiple pigs from that same syringe.
CALCULATE DOSAGE MANUALLY
First multiply the dose (in cc) times the concentration (in mg/ml) to yeild the dose in mg. (note: 1 ml = 1 cc)
0.625 cc X 48 mg/ml = 0.625 cc X 48 mg/cc = 30 mg
Then divide by the weight in kilograms.
30 mg/1kg = 30 mg/kg (dosage)
If this guinea pig weighed only half a kilogram and was being given the same 0.625 cc, he would have been receiving twice the recommended dose because the wrong dosage was being used.
30 mg/0.5 kg = 60 mg/kg (dosage)
So remember: telling someone your guinea pig is getting 0.5 cc of baytril is not helpful unless you provide all of the following information:
- Dose -- the amount in cc you are giving at one time
- Weight of your guinea pig in kilograms AND
- Concentration of the drug in the suspension in mg/ml (mg/cc).
- See: Medications
COMMON MEDICATION DOSAGES
- Chloramphenicol: ORAL Dosage 50 mg/kg q12h
- Doxycycline: ORAL Dosage 5mg/kg q12h
- Enrofloxacin (Baytril): ORAL Dosage 2.5 to 10.0 mg/kg q12h
- Trimethoprim sulfa (Bactrim): ORAL Dosage 30 mg/kg q12h
- Ivermectin: ORAL Dosage 0.2mg/kg
- Ivermectin: TOPICAL Dosage 0.5mg/kg
- Metronidzole (Flagyl): ORAL Dosage 20 to 60 mg/kg q12h
- Selamectin (Revolution): TOPICAL Dosage 10mg/kg
- For more information about these drugs and others, see: Medications
Typically, drugs are administered using a 1 cc needleless syringe. To remove the air in the syringe, draw a little extra medicine, tilt the tip upward, and push the plunger until you have the right dose. Find helpful techniques for giving drugs on the Giving Medications Page.
Draw only one dose at a time! NEVER draw multiple doses into one syringe and attempt to treat multiple pigs with medication.
1 cc syringe
The arrows in the picture below point to 1 cc, 0.5 cc, and 0.1 cc amounts.See: Larger Image
The picture below shows a very small amount, 0.05cc, which is only a few drops.
The concentration of the drug should be written on the drug container. If not, call your vet and ask for the concentration in mg/ml.
If the concentration is not listed in mg/ml but in a different amount, say mg/5 ml, you must divide the mg by the appropriate amount (in this case, 5) to determine the correct suspension in mg/ml.
- Bactrim is often listed as 240 mg/5 ml
- Divide 240 by 5 to determine the mg/ml
- 240 mg/5 ml = 48 mg/ml
If the concentration is listed as a percent (say, 1%), multiply the percent by 10 to calculate the mg/ml.
- Ivermectin can be purchased in a 1% solution
- 1 X 10 = 10 mg/ml
- Ivermectin can also be purchased in an 0.8% solution
- 0.8 X 10 = 8 mg/ml
- Enrofloxacin can be purchased in a 2.5% solution
- 2.5 X 10 = 25 mg/ml
HOW MUCH SHOULD I GIVE?
DOSE IN CC
To figure out how much of a particular drug in a liquid suspension your guinea pig should be given, you need three pieces of information:
- Dosage The amount of the drug to be given per quantity of body weight in mg/kg (See: Medications)
- Weight of your guinea pig in kilograms (see: Conversion Chart)
- Concentration of the drug in the suspension in mg/ml or mg/cc (see: Concentration Tips above)
This handy calculator can help determine how much of a liquid medication to give your guinea pig. Be sure to use the correct dosage (sometimes expressed as a range), the correct guinea pig weight in kilograms, and the concentration of the drug in mg/ml. Double check your answer using a calculator (dosage times weight divided by concentration).
CALCULATE DOSE IN CC
Enter the dosage, weight, and concentration of the drug to calculate the dose in cc you would give your guinea pig. Check the medical guide for more information.
- See: Medications
CALCULATE DOSE IN CC MANUALLY
First determine the dose in mg:
Dosage X Weight = Dose in mg
(the precise amount of the drug that the guinea pig should receive)
A guinea pig of 0.8 kg will be given ivermectin topically at 0.5 mg/kg
0.8 kg X 0.5 mg/kg = 0.4 mg ivermectin
Then determine the dose in cc:
Dose in mg divided by Suspension = Dose in cc
(the precise amount of the suspension containing the correct amount of the drug in mg)
Ivermectin 1% solution has 10 mg/ml (i.e. 10 mg/cc).
Calculate dose in cc for the above pig needing 0.4 mg ivermectin
Dose divided by suspension is 0.4 mg divided by 10 mg/cc = 0.04 cc
Note: there are ivermectin dosing charts on the site. See how your calculations compare with the charts.
Topical Ivermectin Treatment OR Oral Ivermectin Treatment
HOW OFTEN SHOULD I GIVE MY GUINEA PIG THIS MEDICATION?
FREQUENCY The most accurate and easy to understand terminology for describing when to administer drugs is q24h, q12h, q8h etc, where a dose is given and the next dose is given "X" hours later (24 hours, 12 hours, 8 hours, etc.).
Since older terminology may mislead the lay person into the belief that doses need not be spaced evenly over a given period of time, avoid the old terminology:
- SID = daily
- BID = twice daily
- TID = three times daily
- QID = four times daily
And instead use:
- q24h = every 24 hours
- q12h = every 12 hours
- q8h = every 8 hours
- q4h = every 4 hours
GLOSSARY FOR THIS PAGE:
- mg = milligram = a unit of mass or weight = the weight of drug itself
- kg = kilogram = a unit of mass or weight = the weight of your guinea pig is measured in kg when calculating the dosage
- 1 kilo = 1000 grams
(if you have any difficulty converting to kg, see: Conversion Chart)
- ml = milliliter = a unit of capacity = a volume of fluid
- cc = cubic centimeter = a unit of capacity = a volume of fluid
- 1 ml = 1 cc
Many drugs are administered in a liquid suspension:
- suspension = an amount of a drug (in mg) mixed with a fluid (in ml) usually represented as mg/ml (since 1 cc = 1 ml, mg/cc is the same thing)
5 mg ivermectin/ml means each ml contains 5 mg of ivermectin
The dose is quantity of a drug to give your guinea pig at one time.
The dosage is the amount (by weight), frequency, and number of doses to give your guinea pig.
- dose in mg = amount in mg of drug
- dose in cc = amount in cc of liquid suspension containing the drug (see above)
- dosage amount = amount of drug (in mg) per specific weight of pig, usually represented in mg/kg
0.5 mg ivermectin/kg means the dosage for ivermectin is 0.5 mg for every kilogram of pig
1 unit (insulin syringe) = 0.01 cc
One teaspoon = 5ml (or, more accurately, 4.9290 milliliters)
One "drop" is roughly 0.034 cc (3 drops are about 0.1cc).
- - - It is recommended to use more accurate methods of measurement than drops.