How to treat lice in sheep? - briefly
Apply a licensed ectoparasiticide (e.g., ivermectin, doramectin) at the recommended dose, covering the entire fleece and skin. Repeat the dose after 7–10 days and combine with regular shearing and quarantine to prevent reinfestation.
How to treat lice in sheep? - in detail
Effective control of ovine lice requires a systematic approach that combines accurate diagnosis, appropriate chemical or non‑chemical interventions, and ongoing monitoring.
First, confirm infestation by inspecting the fleece and skin. Adult lice and nymphs appear as small, grayish insects moving on the wool. Look for intense scratching, wool loss, and the presence of white, brown, or black nits attached to hair shafts. A thorough visual examination of the back, neck, and hindquarters provides the most reliable assessment.
Once lice are identified, select a treatment method based on herd size, resistance history, and product availability.
Chemical options
- Organophosphate dip (e.g., diazinon) applied at the label‑recommended concentration, ensuring full coverage of the fleece.
- Synthetic pyrethroid spray or pour‑on (e.g., cypermethrin, deltamethrin) administered to each animal, with a repeat dose after 7–10 days to target emerging nymphs.
- Macrocyclic lactone injectable (e.g., ivermectin) given subcutaneously; effective against both lice and many internal parasites, but resistance should be considered.
Non‑chemical options
- Fine‑tooth combing of heavily infested animals to remove adult insects and nits; labor‑intensive but useful for small flocks or in conjunction with medication.
- Strategic shearing to reduce habitat and improve the efficacy of topical treatments.
- Use of diatomaceous earth dusted onto the fleece; works by desiccating insects, but requires repeated applications.
Implement a treatment schedule that includes an initial application followed by a second dose 7–14 days later, aligning with the lice life cycle. Record dates, products used, and dosages for each animal.
After treatment, re‑examine the flock within two weeks. Persistent signs of infestation indicate possible resistance or incomplete coverage; adjust the protocol by rotating to a different class of insecticide or integrating mechanical removal methods.
Maintain flock hygiene to prevent reinfestation: regular shearing, clean bedding, and prompt removal of dead or heavily soiled animals reduce the environmental reservoir of lice.
Finally, establish a preventive program that administers a prophylactic treatment every 3–4 months during peak grazing seasons, monitors for resistance patterns, and documents outcomes to refine future interventions.