# Dosing problems, or, how to learn to love mg/kg

**Here are some “real life” medical dosing questions to solve…remember that cubic centimeters (cc) and milliliters (ml) are equivalent. Dosing information is correct for the drugs and parasites given. Always consult with your veterinarian if you are unsure about the proper dosing information for any medication.**

A) Your alpaca weighs 167 pounds. The vet has prescribed fenbendazole, 10% solution, at 20mg/kg for five days for strongyles. The suspension has 100mg of fenbendazole per ml. How many mls do you need to give the alpaca each day?

B) Your alpaca weighs 122 pounds. The vet has prescribed fenbendazole, 10% solution, at 50mg/kg for five days for meningeal worm treatment. The suspension has 100mg of fenbendazole per ml. How many mls do you need to give the alpaca per day?

C) Your alpaca weighs 101 pounds. The vet has prescribed moxidectin at 0.4mg/kg for a single day dose to combat resistant strongyles. You have Cydectin drench on hand, which has 1mg per ml of moxidectin in it. How many mls do you give the alpaca?

D) Your alpaca weighs 78 pounds. Your vet prescribes amprolium at 10mg/kg for five days on, five days off, five days on for small coccidia. Corid has 96mg of amprolium per ml. How many ml do you give the alpaca each day? (Bonus: what else should you give the alpaca if using amprolium?)

E) An alpaca is receiving 14 mls of fenbendazole 10% suspension daily for parasite treatment at 20mg/kg dosing. There are 100mg per ml of the suspension. How much does the alpaca weigh?

F) An alpaca is receiving 6 mls of Corid daily at the 10mg/kg dosing level. Corid has 96mg of amprolium per ml. How much does the alpaca weigh?

ANSWERS

A) 167 pounds equals approximately 76 kilos. You can use any of many online conversion engines to convert pounds to kilos. You need to give 20mg of fenbendazole for each kilo, so 20*76=1520mg for the daily dose. Each ml of the suspension has 100mg in it, so 1520/100=15.2 ml. Round up when using fenbendazole, so you would give 16ml. The quick and dirty way to figure this is 1ml per 10 pounds body weight (16.7 rounded up to 17ml)

B) 122 pounds equals approximately 55 kilos. You need to give 50mg of fenbendazole for each kilo, so 50*55=2750mg for the daily dose. Each ml of the suspension has 100mg in it, so 2750/100=27.5ml. Rounding up, you would give 28ml. Quick and dirty and close enough is 2.5ml per 10 pounds body weight (30.5 rounded to 30ml)

C) 101 pounds is approximately 46 kilos. You need to give 0.4mg of moxidectin for each kilo, so 46*0.4=18.4mg for the single dose. There is 1mg per ml of moxidectin in the Cydectin drench, so the alpaca would need 18ml (rounding down). The quick and dirty way is 2ml per 11 pounds (101/11=9.2) or 9.2*2=18.4.

D) 78 pounds is approximately 35 kilos. You need to give 10mg of amprolium for every kilo, so 35*10=350. There are 96mg of amprolium in every ml of Corid, so 350/96=3.7ml (round up to 4). Always give injectable thiamine every third day when using amprolium.

E) 14ml of fenbendazole suspension contains 1400mg of fenbendazole (14*100); each ml has 100mg. You are giving 20mg for every kilo, so this would treat a 70 kilo animal (1400/20=70). 70 kilos is approximately 154 pounds.

F) 6mls of Corid contains 576mg of amprolium (6*96); each ml has 96mg. You are dosing at the rate of 10mg/kg, so this amount will treat a 57.6 kilo animal (576/10=57.6). 57.6 kilos is approximately 127 pounds.