Internal parasites are the most common health problem in alpacas, and dewormer resistance is now widespread. The old approach — deworming the whole herd on a calendar — makes things worse. Modern control combines testing, targeted treatment and pasture management.
The main parasites
| Parasite | Why it matters |
|---|---|
| Barber pole worm (Haemonchus) | Blood-sucking; causes severe, sometimes fatal anemia in warm, wet weather |
| Other strongyles, whipworm, Nematodirus | Weight loss, diarrhea, poor growth |
| Coccidia including E. macusaniensis | Diarrhea and weight loss, especially in crias |
| Liver fluke | Wet pastures; can be fatal |
| Meningeal worm | Deer parasite causing neurological disease in eastern North America |
| External: mites, lice, ticks | Skin and fleece damage |
Step 1: Fecal egg counts (FEC)
A fecal egg count (McMaster method) estimates eggs per gram of feces. Run counts:
- every 4–8 weeks during the warm grazing season,
- on every new arrival during quarantine,
- before and 10–14 days after deworming to check the drug worked (fecal egg count reduction test).
Many owners learn to do their own counts with a microscope; your vet or a lab can also run them. Ask the lab to check for coccidia and whipworm, which need special techniques.
Step 2: Check for anemia
FAMACHA eyelid scoring — comparing the inner lower eyelid color with a chart — helps spot barber pole worm anemia. In camelids use it alongside FEC, body condition and, if in doubt, a packed cell volume (PCV) blood test.
Step 3: Targeted selective treatment
- Deworm only animals that need it — high FEC, anemia, weight loss or clinical signs.
- Leaving some healthy animals untreated keeps “refugia”: worms that are still susceptible to drugs, which slows resistance.
- Choose the drug with your vet based on resistance testing. Camelid doses are extra-label and often differ from sheep and goat doses.
- Weigh animals (don’t guess) — underdosing breeds resistance.
Never rotate dewormers blindly or deworm the whole herd every month “just in case”. It is the fastest way to create a farm where no dewormer works.
Step 4: Pasture hygiene
- Pick up dung piles at least twice a week — one of the most effective tools you have.
- Rotate pastures and avoid grazing below about 4 in (10 cm).
- Don’t overstock — use the stocking-rate calculator.
- Rest or hay-cut heavily contaminated paddocks; co-graze with horses.
- Fence off wet areas to reduce fluke and snail habitat.
- Consider tannin-rich forages like sericea lespedeza or birdsfoot trefoil.
Step 5: Know your season
Barber pole worm thrives when monthly average highs exceed about 64°F (18°C) and rainfall is above about 2 inches (50 mm). Our local climate guides list the worm-season months for every U.S. county.
Meningeal worm
In areas with white-tailed deer (eastern and central North America), discuss a meningeal worm prevention plan with your vet. Many farms use a preventive protocol during the snail season, weighing the benefit against resistance in stomach worms. Reduce snail habitat and keep deer out where possible.
Frequently asked questions
How often should I deworm alpacas? Only when testing or signs show it’s needed. Test every 4–8 weeks in warm months.
Do natural dewormers work? Garlic, diatomaceous earth and pumpkin seeds have no proven benefit in camelids. Tannin-rich forages have some research support as a supplement to good management.
Keep reading
This page is educational and does not replace advice from a veterinarian who has examined your animals. Camelid medicine uses many drugs “extra-label”, so dosing must come from your vet. In an emergency, call your vet first. Read our disclaimer · How we write and review content.