This is what I found:
Plumb's & 7th Edition
Plumb's & 9th Edition
The 300 microgram (0.3 mg/kg )dose is for the injectable product, but I guess you could try using the horse paste orally. If one has the 1.87% paste, the math is:
pounds divided by 2.2, times 0.3 (mg/kg), divided by...