Resilience vs. Resistance: Why I'm Not Deworming My Whole Herd

There's a microscope on my kitchen table this week, and I've spent more time looking at goat poop under it than I'd like to admit to dinner guests. I ran a sample on every animal in the herd — does, bucks, the whole roster — slid each one under the lens, and counted eggs against the little identification chart until my eyes crossed. It is not glamorous work. It is, however, the single most useful thing I've done for this herd all spring.

Because here's what the microscope made impossible to ignore: my goats are not all carrying the same load. Not even close.

The short version

In almost every herd, a small handful of animals — often cited as around 20% of the herd — carry roughly 80% of the total worm burden and do most of the pasture contamination. That's not a guess; it's how parasites distribute themselves, and it's been documented in small ruminants for years. The takeaway is brutal and freeing at the same time: deworming every goat on the calendar is mostly wasted product, and worse, it's how you breed dewormers that don't work anymore. The smarter move is to find your heavy shedders and treat them — which means you have to actually look, not guess.

Two kinds of "tough," and breeders mix them up constantly

This is the part nobody explains clearly, so I'm going to.

Resistance is a goat's ability to keep worms out. A resistant doe's immune system fights the parasites off, so she carries a low burden and sheds very few eggs. You want this.

Resilience is a goat's ability to stay healthy and productive despite carrying worms. A resilient doe can have a respectable worm load and still hold her condition, milk like a champ, and raise fat kids. She looks fantastic.

Here's the trap: resilient is not the same as clean. The most dangerous animal in a parasite program is the doe who is resilient but not resistant — she looks like a million dollars, so you'd never think to treat her, and meanwhile she's quietly pumping eggs all over the pasture your newborn kids are about to walk on. You can't see that with your eyes. I couldn't. However, the microscope did.

The dream is a goat who's both — resistant and resilient. Those are the animals you build a herd on. And the only way to find out who they are is to test, not admire.

The other "resistance" — the one on the wormer label

While we're untangling words: there's a second resistance in this conversation, and it's the worms' fault, not the goat's. Anthelmintic resistance is when the worms themselves stop dying when you deworm. Decades of treating every animal, every season, on a schedule, did this to us — we killed off all the susceptible worms and left the survivors to breed.

Which is the whole reason the calendar approach backfires. Every blanket deworming is a selection event for super-worms. The fix is something called refugia — deliberately leaving some worms un-exposed to the dewormer (the ones in your healthy, untreated animals and out on pasture) so the worm population stays susceptible and the drugs keep working. Treating only your heavy shedders isn't just efficient. It's how you protect the few tools we have left.

What we actually do here

I check animals using FAMACHA (eyelid color to catch the barber pole worm, the blood-feeder that kills goats fastest), body condition, and now fecal egg counts off the scope — and I treat the goats that need it, not the calendar.

I reach for natural support first.

Herbal dewormers earn their keep best as maintenance and prevention in resilient, low-load animals. They are not a rescue for an anemic goat with a heavy barber pole load. When FAMACHA tells me an animal is in real trouble, I go to an effective chemical dewormer — one I've confirmed still works on this farm — without apology.

Why I'm doing all this now

Timing is everything in Michigan. Our kids hit the ground in that moody March-and-April stretch where the weather can't decide what it is — and right around kidding, a doe's immunity relaxes and her egg-shedding spikes (the spring rise). That dumps larvae onto pasture exactly when the kids arrive with zero immunity of their own. If I can find and knock down my heavy shedders before the grass greens up and the babies are out walking through it, I break that cycle before it starts. The microscope isn't a gadget. It's me trying to give this year's kids a fighting start.

(If you want to go deeper, the American Consortium for Small Ruminant Parasite Control — wormx.info — is the real-deal free resource the egg-ID chart on my table came from. Worth every minute.)

So — do you know who your 20% are? I'd love to hear whether you've started counting. (I get into our full herd-health and breeding-selection approach in my book — including how I choose which animals stay.