Scouring lambs, the first drench and Barber's pole: what to check before you drench

🐑 The short version

Look before you drench, and look at the right lambs.

A lamb with a dirty back end in spring isn't proof of worms. Rich spring grass can do it on its own, and scouring is one of the later signs of a worm problem, not the first. Barber's pole, the worm most likely to kill a lamb in the warmer parts of New Zealand, usually doesn't cause scouring at all. It causes anaemia: lambs that lag behind, sit down when the mob is moved, and have pale or white eyelids.

So there are two cheap things to do before reaching for the drench gun: pull down a few lower eyelids, and get a faecal egg count done. If you do drench, use a product that has worked on your farm, dose to the heaviest lamb, and check 10 days later that it worked.

🔍 First question

Is a scouring lamb a wormy lamb?

Sometimes. Beef + Lamb New Zealand's Wormwise handbook lists weight loss, scouring and dehydration as the major physical signs of worm disease, but it describes them as the end stage. By the time you can see them, the worms have been at work for a while.

Scouring has other causes too. NZ Lifestyle Block's November farming tips point out that diarrhoea in lambs may come from rich pasture rather than parasites, and in spring the grass is at its richest. One mucky lamb in a mob that is otherwise growing well tells you very little on its own.

A better question is whether the lambs are growing. The same November tips give a rough target of about 300 grams a day for lambs. Weigh a few now and again in a fortnight. A lamb that is scouring and growing is a different problem from a lamb that is scouring and going backwards.

🩸 The dangerous one

Barber's pole looks different from other worms.

Barber's pole (Haemonchus contortus) lives in the fourth stomach and sucks blood. The Wormwise handbook says it can kill lambs through anaemia and blood loss. Because it takes blood rather than upsetting the gut, it often doesn't cause a scour. Totally Vets says scouring is not typical with Barber's pole.

What you see instead, from Totally Vets and VetEnt:

• No stamina. Lambs can't keep up with the mob and often sit down when the animals are moved.
• Fast, shallow breathing after a little exercise.
• Pale gums and eyelids, and sometimes bottle jaw, a soft, fluid swelling under the jaw.
• Ill-thrift, a lamb that just isn't doing.
• Sudden deaths. Lambs can be found collapsed or dead with no warning.

That last one is why Barber's pole matters more than its signs suggest. A heavy burden can build quickly, and the first thing some people notice is a dead lamb. If you've had Barber's pole on your property before, assume it is still there.

👁️ Costs nothing

The free check: pull down the lower eyelid.

Hold the lamb, put your thumb just below the eye and gently pull the lower lid down. Look at the pink lining inside.

• Salmon pink is healthy.
• Pale pink is worth watching.
• White is a lamb in trouble. Totally Vets describes the membranes of a lamb with a heavy burden as "ghostly white".

Totally Vets says not to rely on the gums in lambs, because they often look pale even in healthy animals. Check the eyelids instead, and check the slow ones at the back of the mob first.

This check only tells you about anaemia, so it finds Barber's pole and misses the other worms. It's a screen, not a diagnosis. A white-eyed lamb is a reason to ring your vet today, not to guess at a drench.

📅 Timing

When Barber's pole strikes.

The Wormwise handbook says Barber's pole is more of a problem in the warmer parts of the North Island and the upper South Island, and puts its danger period in late summer and autumn. Totally Vets says the odd case turns up before Christmas, and that outbreaks tend to follow rain or heavy dew after a hot, dry spell, when the number of larvae on the pasture can climb quickly.

So late spring is the time to find out where you stand, before the risky months arrive. Beef + Lamb NZ notes that in the upper half of the country, a larval culture on lambs before weaning can show early Barber's pole levels, and that very high egg counts at this time of year are a warning sign of an early Barber's pole season.

❓ The big decision

Do lambs need a drench before weaning?

Not always. VetSouth notes that many farmers still drench four weeks before weaning out of habit, while others are moving to drenching only when it's needed. Beef + Lamb NZ says a pre-weaning drench may do little to improve lamb growth where the ewes lambed in good condition, though it can help on country recovering from drought or weeks of wet weather. They also flag late-spring drenching as a risk for drench resistance.

That's the case for testing first. A low egg count is a reason not to drench, and every drench you don't need is one less push towards resistance. A high count, or a culture showing Barber's pole, is a reason to drench with confidence.

One thing a small block can't easily do is move lambs to clean pasture. The Wormwise handbook notes that on lifestyle blocks there is limited scope for managing worms through grazing swaps and rotations, so good feeding matters more. Beef + Lamb NZ suggests land grazed by another species, such as cattle, as cleaner feed for lambs. If you run both, use it.

🧪 Simpler than it sounds

Getting an egg count done.

A faecal egg count (FEC) counts worm eggs in a dung sample. It sounds like a job, but most of the work is a phone call and a morning in the paddock.

1. Ring your vet clinic. Most do egg counts. Ask what it costs, whether they supply sample pottles or bags, and how soon they need the samples. Ask about a larval culture too. An egg count tells you how many eggs; a larval culture tells you which worms they are, including Barber's pole. The Wormwise handbook says a culture takes 10 to 14 days and identifies the type of worm, not how many there are.
2. Sample about 10 lambs. The Wormwise handbook says a mob result needs samples from at least 10 animals. Pick lambs from across the mob, not just the scouring one.
3. Take it fresh. At least a tablespoon from each lamb, still warm, one lamb per freezer bag or pottle. First thing in the morning is easiest, when they get up and go. Pen them for a few minutes if you need to.
4. Keep it cool. In the fridge, not the freezer, until it goes to the clinic. Same day is best.
5. Keep the samples separate and let the lab mix them if they're pooling. The Wormwise handbook prefers individual samples, because a few lambs often carry most of the worms.

Ask your vet to talk you through the result. What counts as high depends on the age of the lambs, what they've been grazing and how they're growing, and the handbook says the number has to be read with all of that in mind.

💉 Doing it properly

If you do drench.

• Use a product that works on your farm. Beef + Lamb NZ says to choose one shown to be highly effective on your farm in the last 12 months. VetSouth's advice where no drench testing has been done is a triple combination drench, followed by a drench check. Spring worms differ from autumn ones, so an autumn result may not apply now. Which product is a question for your vet, especially if you've had Barber's pole.
• Weigh, and dose to the heaviest. Under-dosing lets the toughest worms survive. Weigh a few lambs and dose the mob to the heaviest. Our drench resistance guide covers dosing properly.
• Check that it worked. The Wormwise handbook's drench check is 10 fresh samples taken 10 days after drenching (7 to 14 is acceptable). Eggs in those samples mean the drench went in wrong or resistant worms survived it. Talk to your vet if you find any.
• Leave at least 28 days between drenches. The handbook gives 28 days as the usual minimum interval for young stock. Totally Vets says not to stretch it beyond that for lambs on contaminated pasture where Barber's pole is about.
• Mind the withholding period before any lamb goes to the works or the freezer.

📲 Keeping track

Keeping track of it.

Worm problems repeat on the same block in the same months. What you write down this spring is what tells you what to expect next spring. Worth recording:

• Weights, so you can see which lambs are going backwards.
• Eyelid checks, by lamb, if any were pale.
• Egg counts and cultures, with the date and the result.
• Every drench: the product, the dose, the date and which lambs.
• The drench check, and whether it came back clear.

My Block Hand keeps weights on each animal and checks a drench dose against the label rate and the heaviest weight on file. It works out the withholding date, books the next round if you set it to repeat, and reminds you about twelve days after a drench to check whether it worked. Egg count results can go on as one dated note across the whole mob.

🚧 Where this guide stops

What this guide cannot do for you.

This is general information for lifestyle-block sheep owners, written from Northland. It doesn't recommend a drench product or a dose, and it can't see your lambs. A lamb with white eyelids, a lamb that can't keep up, or any unexplained death is a reason to call your vet straight away.

📚 Further reading

Where the information on this page comes from.

• Beef + Lamb NZ — Wormwise handbook (2026): signs of worm disease, where and when Barber's pole is a problem, lifestyle blocks, minimum drench intervals, taking samples, larval culture and the drench check.
• Beef + Lamb NZ — Pre-weaning worm management hacks for lambs: whether a pre-weaning drench pays, late-spring resistance risk, choosing a drench, the 10-day check, and early warning of Barber's pole.
• Totally Vets — Barber's pole worm: signs, the eyelid check, when outbreaks happen, drench intervals and testing.
• VetEnt — Barber's pole in sheep: signs including pale gums and eyelids and bottle jaw.
• VetSouth — Giving your lambs their first drench: drenching by habit versus by need, and what to use when your drench hasn't been tested.
• NZ Lifestyle Block — 25+ farming tips for November: growth targets, testing before drenching, and rich pasture as a cause of scouring.