Importance of Quarantine Deworming
There are two ways to get dewormer-resistant worms: breed your own or import them from someone else's farm. Sheep and goat farms in the US without dewormer-resistant worms are rare. Assume that any sheep or goat brought to your farm is carrying worms with some degree of dewormer resistance.
To prevent the introduction of dewormer-resistant worms, you should quarantine drench all sheep and goats that are new to your property. A dewormer from each of the three chemical classes should be given. This is usually albendazole (Valbazen®) + moxidectin (Cydectin®), and levamisole (Prohibit, LevaMed®). Administer each of these drugs sequentially in a separate syringe (or gun) or dose. In non-US countries, other drug actives or multi-active drugs may be available.
Each of the drugs in the quarantine treatment is FDA-approved for sheep, but not goats and camelids. For goats and camelids, extra label drug use is required (valid veterinarian-client-patient relationship). Copper oxide wire particles (COWP) can also be added to the treatment combination (in barber pole worm prevalent areas). Be sure to use COWP safely.
After deworming, it is important to hold the animals in quarantine for at least three days to allow the worms present at the time of drenching to leave the gut. Doing a fecal egg count 10 to 14 days after quarantine drenching will give proof that the treatment was effective.
For other biosecurity concerns, it is best to leave new animals in quarantine for 4 weeks. After quarantining, the animals should be released onto a pasture (paddock) that is likely to be contaminated with worms from other grazing sheep/goats.