Chris Gregory BVSc MRCVS, Molecare Veterinary Services
Last month’s article looked at the risk factors for fluke infestation and testing options. This instalment looks at appropriate treatments available and when to treat. A vast array of products exist, and not all products kill all stages of fluke within the animal. The scope of this article is not to give detailed recommendations on when and what to treat with, more to highlight some of the important considerations in making those core health-planning choices. Products and timings will be particular to each unit depending on fluke risk, housing arrangements, handling systems, meat withdrawals and type of stock.
(2) Treatment Options & Timing
At housing, an animal could be harbouring multiple stages of the fluke parasite depending on pasture risk and seasonal exposure ranging from:
- Fresh fluke cysts ingested off pasture – effectively ‘day 0’ of infestation
- Early Immatures
- Late Immatures
- Adult fluke in the liver (gall bladder and bile ducts) – ~10-12 weeks after ingesting the cyst
- Only at this point will fluke eggs be identifiable in dung samples.
As we said previously, winter housing offers a unique opportunity to interrupt the pasture-based fluke lifecycle. Once housed there are no more fluke cysts ingested, potentially allowing all current immature stages to catch-up to the adults. Theoretically, after 10-12 weeks (mid-late housing period) only adult stages would exist in the animals.
Looking at the table below, different products kill fluke stages from 2 weeks post ingestion all the way through to adults at 10-12 weeks + post ingestion NB. None of the products kill fluke less than 2 weeks old. This presents a range of possibilities with respect to timing treatments.
- Treat at housing:
Systems geared around minimal handling e.g. housed forward stores or fat cattle close to finishing that will not go back out to grazing. In this case a housing dose reduces the stress/growth check of additional gatherings for treatment(s). Although there will be some stages of fluke untreated, most of the grazing burden is cleared and impact on growth rate reduced. Commonly a combination product to eliminate worm burdens will be used with this strategy to maximise the efficiency of the single dose at housing approach.
- Delay treatment:
Systems capable of multiple handlings and animals less prone to growth checks (e.g. suckler cows). A single treatment could be delayed until a product has its maximum effect.
e.g. Triclabendazole – delay treatment until 3 weeks after housing
e.g. Clorsulon/Closantel – delay treatment until 8 weeks after housing
- Additional pre-turnout treatment:
Where there is any suspicion of fluke stages left untreated, an additional late housing dose could be carried out. Especially if the cattle are to return to grazing the following spring.
e.g. Cattle dosed at housing for convenience may still have a residual fluke burden.
e.g. Systems where cattle out-winter or have limited access to grazing may re-infect after initial treatment as none of the fluke products have persistency.
Any cattle that carry a residual adult fluke burden through housing will begin to contaminate pasture immediately after they are turned out again.
|Active Ingredient||Product Name
|Stage of Fluke Targeted, Post Ingestion of Cysts
|Method of administration||Meat Withhold
|‘Fasinex’, ‘Combinex*’, ‘Tribex’, ‘Triclafas’, ‘Endofluke’||2 weeks +||Oral||56|
|‘Cydectin-Triclamox*’||6-8 weeks +||Pour-on||143|
|Closantel||‘Closamectin*’||7 weeks +||Subcutaneous inj.||49|
|‘Closamectin*’||7 weeks +||Pour-on
|‘Trodax’||8 weeks +||Subcutaneous inj.||60|
|‘Virbamec*’, ‘Animec*’, ‘Ivomec Super*’, ‘Bimectin Plus*’||Adult fluke 8-12 weeks +||Subcutaneous inj.||66|
|‘Rumenil’, ‘Zanil’,||Adult fluke 8-12 weeks +||Oral drench||13|
|‘Endospec’, ‘Albenil’, ‘Albex’||Adult fluke 8-12 weeks +||Oral drench||14|
Fluke treatment strategies are a core component of a solid herd health plan, relying on informed product knowledge and tailored use specific to a farming system. As always, your herd vet and local SQP are the best resources for advice when considering what treatments to use and when.