Selamectin -- (Revolution) Calculate Dose in mg and cc
A newer treatment for mites and lice requiring a prescription. Apply topically to the skin. Pfizer reportedly advises 10mg/kg for cavies. Selamectin does not have ivermectin's proven safety track record but some cavy owners appreciate the convenience of once a month topical dosing.

NOTE: Tubes come in different concentrations (either 60mg/cc or 120 mg/cc). Individual tubes contain from 15mg to 360 mg selamectin and vary from 0.25cc to 3 cc by volume.
Example: Mauve tube treats up to 2.5kg of cat and contains 15mg per tube. [Each tube contains 0.25cc at 60mg/ml -- see PICTURE OF PACKAGE]

So if the concentration is 60mg/cc and the dosage is 10mg for a one kilo pig, the dose is 0.167cc. If you use the 120mg/cc tubes (which are twice as concentrated), the dose is smaller: 0.0833cc for a one kilo pig. To dose individual pigs, multiply their weight in kilos times either 0.0833cc (for the 120mg/cc tubes) or 0.167cc (for the 60mg/cc tubes).
Example: for a pig of 0.5 kilos using a 60mg/ml concentration:
0.5kg X 0.167cc/kg = 0.0835cc Dosage: 10mg/kg

See also: Efficacy and Safety of Selamectin (Stronghold®/Revolution™) Used Off-Label in Exotic Pets - the authors cite recommendations by Beck of "15 mg selamectin for animals weighing less than 800 g body weight and 30 mg for animals heavier than 800 g body weight applied as a spot-on to the skin of the neck." While this would work out to 18.75mg/kg for an 800 gm pig and 37.5 mg/kg for an 801 gm pig (a very large dose), 10 mg/kg is adequate for treatment. We recommend a dose calculated accurately by weight. This information is presented to suggest a margin of safety, not to suggest using high doses.

source: http://www.guinealynx.info/antiparasitics.html