Food Animal Drug Regulations
Minor Species: It is very expensive to get drugs approved; hence many drug manufacturers stop after one indication or species. Due to the limited financial gains from marketing for sheep and goats, these animals have limited to no approved drugs.
Minor Use: Similarly, it would not be financially acceptable for drug companies to test their drugs on every condition individually. The less common diseases (about everything except endotoxemia, fever, respiratory disease and footrot) don’t often have approved drugs. Extra label use is required if not FDA approved drug exists.
The act was also designed to incentivize companies to actually get approval for these conditions and species but that has not worked very well.
The UK uses 7 days milk/28 days meat minimum withhold if the drug is not specifically licensed for goats.