The proper way to use liquid ivermectin for dogs is to dilute the ivermectin with propylene glycol (or possibly food-grade (USP) glycerin -- I have not actually seen instructions using glycerin rather than propylene glycol, but liquid ivermectin injectable solutions are made with 40% glycerol and 60% propylene glycol). Some people have used vegetable oil instead because it tastes better and is easier to get, but the drug will not mix as well with oil and so the dosage within the solution may not be even. Without diluting the ivermectin solution, the amount to give is too small to measure accurately.

Ivermectin 0.27% solution is the easiest to use, especially for small dogs. A 200 ml bottle of ivermectin 0.27% solution costs around $50, and would be enough to treat 200,000 lbs of dogs.

Ivermectin 1% solution is more readily available and can also be used, especially for larger dogs. A 50 ml bottle of ivermectin 1% solution costs around $35 and would be enough to treat 150,000 lbs of dogs.

There are instructions below for creating a 30:1 dilution, which works best for small dogs and can also be used for large dogs. Below that are instructions for creating a 9:1 dilution, which can be used for large dogs but does not work well for small dogs, since the dosage is so small.

Keep Ivomec and any unused mixture refrigerated. The length of time the diluted mixture will remain potent is unknown.

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Directions for making 30:1 dilution:

Shake well before using to mix the ivermectin evenly.

Dosage using Ivermectin 0.27% solution at 30:1 dilution:
Give 0.3 cc or ml (cc is the same as ml) of the mixture orally per 10 lbs of body weight.

Dosage using Ivermectin 1% solution at 30:1 dilution:
Give 0.1 cc or ml (cc is the same as ml) of the mixture orally per 10 lbs of body weight.

To make a small amount of the mixture, you will need a 1 cc syringe that measures accurately to the tenth of a cc. Draw up 0.1 cc of Ivermectin solution in a 1 cc syringe, and mix well with 3 cc of propylene glycol, giving you 3 ccs at a dilution ratio of 30:1. This is enough to treat 100 lbs of dogs using the 0.27% solution, or 300 lbs of dogs using the 1% solution.

To make larger amounts of the mixture, use a 1 fluid ounce dropper bottle, which is 30 ml. Put 1 ml of ivermectin solution in a 1 fluid ounce dropper bottle, then fill with propylene glycol. This will be enough to treat 1,000 lbs of dogs (e.g., 100 10-lb dogs or 50 20-lb dogs) if using the 0.27% solution, or three times that much using the 1% solution.

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Directions for making 9:1 dilution:

Shake well before using to mix the ivermectin evenly.

Dosage using Ivermectin 0.27% solution at 9:1 dilution:
Give 0.1 cc or ml (cc is the same as ml) of the mixture orally per 10 lbs of body weight.

Dosage using Ivermectin 1% solution at 9:1 dilution:
Give 0.03 cc or ml (cc is the same as ml) of the mixture orally per 10 lbs of body weight.

To make a small amount of the mixture, you will need a 1 cc syringe that measures accurately to the tenth of a cc. Draw up 0.1 cc of Ivermectin solution in a 1 cc syringe, and mix well with 0.9 cc of propylene glycol, giving you 1 cc at a dilution ratio of 9:1. This is enough to treat 100 lbs of dogs using the 0.27% solution, or 333 lbs of dogs using the 1% solution.

To make larger amounts of the mixture, use a 1 fluid ounce dropper bottle, which is 30 ml. Put 3 ml of ivermectin solution in a 1 fluid ounce dropper bottle,  then fill with propylene glycol. This will be enough to treat 3,000 lbs of dogs (e.g., 30 100-lb dogs) if using the 0.27% solution, or three times that much using the 1% solution.

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Buy Ivermectin, Propylene Glycol and Glycerin:

Valley Vet 800-419-9524
Ivermectin 1% solution, 50 ml, $34 (free shipping).
Propylene glycol, 1 gallon, $19 + shipping.
Glycerin, 1 gallon, $25 + shipping.

The Chemistry Store 800-224-1430
Propylene glycol, 1 quart, $12 + shipping.
Glycerin, 1 quart, $11 + shipping.

If you use this product, you would want to give 1/4 the dosage they recommend, which would require a 1 cc syringe rather than what appears to be a larger syringe that they send with the product, in order to accurately measure the smaller dosages. At a 19:1 dilution, dosage would be 0.06 mg per 10 lbs of body weight, which should be rounded up so that you always give at least the minimum dosage:

10 lbs: 0.06 ml or cc -- round to 0.1 cc
15 lbs: 0.09 ml or cc -- round to 0.1 cc
20 lbs: 0.11 ml or cc -- round to 0.2 cc
25 lbs: 0.14 ml or cc (Blue) -- round to 0.2 cc
30 lbs: 0.17 ml or cc -- round to 0.2 cc
40 lbs: 0.22 ml or cc -- round to 0.3 cc
50 lbs:  0.28 ml or cc (Green) -- round to 0.3 cc
100 lbs:  0.55 ml or cc (Brown) -- round to 0.6 cc

The web site does not say what the ivermectin is mixed with. I know nothing about this company other than what is found on their web site.

How the calculations were done

Heartgard Blue for dogs up to 25 lbs has 68 mcg ivermectin
Heartgard Green for dogs 26-50 lbs has 136 mcg ivermectin
Heartgard Brown for dogs 51-100 lbs has 272 mcg ivermectin

1 cc of ivermectin 0.27% contains 2,700 mcg; 0.1 cc = 270 mcg ivermectin
1 cc of ivermectin 0.27% diluted 9:1 contains 270 mcg; 0.1 cc = 27 mcg ivermectin
1 cc of ivermectin 0.27% diluted 30:1 contains 90 mcg; 0.1 cc = 9 mcg ivermectin

1 cc of ivermectin 1% contains 10,000 mcg; 0.1 cc = 1,000 mcg ivermectin
1 cc of ivermectin 1% diluted 9:1 contains 1,000 mcg; 0.1 cc = 100 mcg ivermectin
1 cc of ivermectin 1% diluted 30:1 contains 333 mcg; 0.1 cc = 33 mcg ivermectin

1 cc of ivermectin 0.08% sheep drench solution contains 800 mcg; 0.1 cc = 80 mcg

The exact dosage using a 30:1 dilution mixture of ivermectin 0.27% solution would be 0.3 ml per 10 lbs of body weight:
10 lbs: 0.3 ml or cc
15 lbs: 0.5 ml or cc
20 lbs: 0.6 ml or cc
25 lbs: 0.8 ml or cc (Blue)
30 lbs: 0.9 ml or cc
50 lbs:  1.5 ml or cc (Green)
100 lbs:  3.0 ml or cc (Brown)

 The exact dosage using a 30:1 dilution mixture of ivermectin 1% solution would be 0.824 cc per 10 lbs. of body weight:
10 lbs: 0.08 ml or cc
15 lbs: 0.12 ml or cc
20 lbs: 0.17 ml or cc
25 lbs: 0.21 ml or cc (Blue)
30 lbs: 0.25 ml or cc
50 lbs:  0.41 ml or cc (Green)
100 lbs:  0.82 ml or cc (Brown)

The exact dosage using a 9:1 dilution mixture of ivermectin 0.27% solution would be 0.1 ml per 10 lbs of body weight:
10 lbs: 0.1 ml or cc
20 lbs: 0.2 ml or cc
25 lbs: 0.25 ml or cc (Blue)
30 lbs: 0.3 ml or cc
50 lbs:  0.5 ml or cc (Green)
100 lbs:  1.0 ml or cc (Brown)

The exact dosage using a 9:1 dilution mixture of ivermectin 1% solution would be 0.0272 ml per 10 lbs of body weight:

10 lbs: 0.03 ml or cc
20 lbs: 0.06 ml or cc
25 lbs: 0.07 ml or cc (Blue)
30 lbs: 0.09 ml or cc
50 lbs:  0.14 ml or cc (Green)
100 lbs:  0.27 ml or cc (Brown)

 The exact dosage using undiluted  ivermectin 0.08% sheep drench solution would be 0.034 cc per 10 lbs. of body weight:
10 lbs: 0.04 ml or cc
15 lbs: 0.05  ml or cc
20 lbs: 0.07 ml or cc
25 lbs: 0.09  ml or cc (Blue)
30 lbs: 0.1 ml or cc
50 lbs:  0.17 ml or cc (Green)
100 lbs:  0.34 ml or cc (Brown)

It's not necessary to be quite so exact, but you should give at least the amount shown (round up).

For the most part, larger dosages are safe, as long as your dogs are not infected with heartworms (in which case, very high doses may kill off too many microfilariae at once, which can lead to an anaphylactic reaction), or if your dogs have the mutation that makes them more susceptible to ivermectin. Even then, as long as you're close to the dosage above, you should be fine, it's just when you give 10 times as much as you should or more that you might run into trouble. This is quite common if you follow recipes on the internet, which often leave out the fact that the ivermectin must first be diluted 9:1 with another liquid, making the dosage ten times what it should be.

http://web.archive.org/web/20061104194714/http://www.heartwormsociety.org/katrina.htm
"Be careful when calculating doses and administering ivermectin solution, as the concentration in most available solutions is very high compared to the dose needed for small animal treatment. Remember 1% solution = 1 gram/100 ml = 10 mg/ml = 10,000 ug/ml [ug=mcg]. . . . People often dilute 1% solution with 99 mls of propylene glycol [dilution ratio of 99:1], to create a solution that is 100 micrograms per ml. The preventive dose of ivermectin for a 10 kg [22 lb] dog then would be .5 mls."

http://www.espomagazine.com/vet/apr96.htm
"As mentioned in that article, the dose of Ivermectin necessary to treat or prevent intestinal parasites is about 30 times the dose used to prevent heartworm disease. The dosage you listed, 0.1 cc per 10 lbs. of body weight, is the dosage recommended for the prevention of intestinal parasites and heartworms [thus, it's 30 times higher than needed to prevent heartworms alone]. Therefore, if you wish to use the cattle wormer, Ivamec, as a heartworm preventative only, the amount needed would, indeed, be too minute to measure accurately. One way to solve the problem is to dilute a small amount of Ivamec in vegetable oil or propylene glycol (a solvent sometimes used to treat bloat in livestock). The vegetable oil tastes better, but the drug will mix better with propylene glycol because that is the same liquid used to dissolve the Ivermectin in a bottle of Ivamec.
"One dilution scheme which would minimize waste would involve using a 1 cc syringe and the more common 3 cc syringe. Draw up 0.1 cc of Ivamec, using the small syringe, and mix well with 3 cc of vegetable oil or propylene glycol [this is a dilution ratio of 30:1]. Using this diluted product, the heartworm preventative dose would be a familiar .1 cc per 10 lbs. of body weight. A larger amount could be diluted and stored in the refrigerator for future use, but the length of time its potency would remain is unknown."