How often should I worm my goats? The smart alec reply is "as often as they're wormy." But that can be difficult to determine. Worming goats is a tricky business - worm too often and you allow the parasites to become immune to the wormer. Don't worm often enough and you lose goats. There are a few ways of testing whether your goats are wormy - ranging from Famacha eye scores and body condition scores to fecal egg counts. But the frequency of worming can vary drastically depending on your environment.
In dry or cold climates like Arizona or Montana, parasites will likely have a much harder time surviving than in more humid climates like Florida. Here in Oklahoma, our weather can be quite varied - but it usually leans slightly to the heavy side of the parasite range.
But the biggest factor affecting how often you worm is the parasite resistance of your herd. When we started off, we wormed about 4 times a year (and lost a lot of goats anyway). Thanks to a lot of hard culling, now we only have to worm one (or in wet years two) times a year. It takes a lot of effort to produce a herd that can hold its own against the parasites - but the reduced management time more than compensates for it.
The best way we've found for determining the parasite resistance of your herd without breaking the bank on vet bills is to keep some records of the Famacha eye scores. This also lets you know which does have the heaviest parasite loads. Using this information, you will be able to identify the goats that need to be sold and the ones that should be bred.