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Brand: FENAFLUKE 5% w/v Oral Suspension

Company: PHARVET

FORMULATION: «drench» for oral administration.


CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED (spectrum of activity)

Cattle & Sheep


  • For sheep, the recommended therapeutic dose is 7.5 mg fenbendazole and 7.5 mg rafoxanide per kg bw (equivalent to 1.5 mL product per 10 kg bw).
  • For cattle, the recommended therapeutic dose is 11.25 mg fenbendazole and 11.25 mg rafoxanide per kg bw (equivalent to 11.25 mL product per 50 kg bw).

Read the product label for specific details on dosage.

* Country-specific differences may apply: read the product label.


  • LD50 (acute oral) in rats:
    • rafoxanide: >2000 mg/kg (for the a.i.)
    • fenbendazole: a.i. >10000 mg/kg (for the a.i.)
  • LD50 (acute dermal) in rats: n.a.

Suspected poisoning? Read the articles on fenbendazole safety and rafoxanide safety in this site.

Withholding periods (=withdrawal times) for meat & milk (country-specific differences may apply: read the product label)

  • Meat:
    • Cattle Ireland 60 days
    • Sheep Ireland 54 days
  • Milk: Ireland
    • Not authorised for use in animals producing milk for human consumption including during the dry period.
    • Do not use during the last trimester of pregnancy in heifers which are intended to produce milk for human consumption.
    • Do not use within 1 year prior to the first lambing in ewes intended to produce milk for human consumption.

WARNING !!!: Never use on humans, dogs or cats

You may be interested in the following articles in this site dealing with the general safety of veterinary products:


Risk of resistance: YES.

Resistance of gastrointestinal roundworms to all benzimidazoles (incl. fenbendazole) in ruminants is a very serious and increasing problem worldwide, particularly in sheep and goats, but also in cattle. The most affected worm species are:

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it may be due to resistance and not to incorrect use, which is usually the most frequent cause of product failure.

There are also a few reports of resistance of Haemonchus spp to rafoxanide, but its certainly not comparable with the high prevalence and frequency of resistance to benzimidazoles.

Alternative chemical classes/active ingredients to prevent resistance of gastrointestinal roundworms through product rotation:

These alternative products may not be available in all countries, or may not be available as drenches, or may not be effective against all the concerned parasites.

There are only very few reports on resistance of Moniezia spp tapeworms to benzimidazoles (not in Europe) but it is certainly not a widespread problem so far.

It is highly recommended to periodically check the resistance status of each property performing appropriate tests (e.g. fecal egg counts) under supervision of a veterinary doctor. Such tests are now routinely available for most producers in developed countries.

Learn more about resistance and how it develops.


Are the active ingredients of this product ORIGINAL* or GENERICS**?


*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.

COUNTRIES where this brand/product is marketed: Ireland
GENERIC BRANDS available? Yes, but rather few in most countries with this particular composition, if at all.

Click here to learn more about GENERIC vs. ORIGINAL drugs.

For an overview on the most used antiparasitic drench brands click here.


FENAFLUKE 5% Oral Suspension from PHARVET is a classic combination drench: fenbendazole is effective against roundworms and tapeworms, and rafoxanide is effective mainly against flukes and a few roundworms. However, this particular combination is nowadays rather unusual because rafoxanide has been abandoned in many countries. However, increasing liver fluke resistance to benzimidazoles may support again the use of rafoxanide.

Fenbendazole is a veteran anthelmintic introduced in the 1970s (by HOECHST, now MSD = MERCK ANIMAL HEALTH). Fenbendazole has a broad-spectrum of activity against roundworms (gastrointestinal and pulmonary) & tapeworms, but is ineffective against flukes. Fenbendazole also kills eggs of roundworms (ovicidal activity). As all benzimidazolesfenbendazole has no efficacy whatsoever against external parasites (ticksflies, lice, mites, etc). Among the benzimidazoles fenbendazole is quite comparable with oxfendazole in terms of efficacy and safety. Fenbendazole is used a lot in livestock and horses, much less in pets. It is not used in agriculture.

As all benzimidazoles (as well as other anthelmintics such as levamisole, monepantel, and tetrahydropyrimidines), fenbendazole administered as a drench has no residual effect, i.e. it kills the parasites shortly after administration, but does not significantly protect the animals against re-infestation by infective stages in their environment.

Unfortunately, resistance of several gastrointestinal roundworms to all benzimidazoles (including fenbendazole) is already very high and very frequent worldwide in sheep and goats, slightly lower in cattle. The presence of rafoxanide in this product may ensure efficacy against benzimidazole-resistant Haemonchus contortus, but not against other resistant worms.

Rafoxanide is a narrow-spectrum salicylanilide introduced in the 1970s (by MS&D AgVet, now Merial). It is effective against liver flukes (Fasciola hepatica mature and immature over 8 weeks of age) and a few gastrointestinal nematodes such as Haemonchus spp and Bunostomum spp. It is not used in pets or horses, and nowadays usage in livestock is very scarce because other flukicides (e.g. closantel, triclabendazole, oxyclozanide) are often preferred in combinations. It is not used in agriculture.

Nowadays more convenient pour-ons and injectables containing macrocyclic lactones (e.g. abamectin, doramectin, eprinomectin, ivermectin, moxidectin) are often preferred over drenches with benzimidazoles or combinations. Macrocyclic lactones also ensure several weeks protection against re-infestation by several worm species, in contrast with all benzimidazoles that lack any residual effect.

In ruminants, reducing the amount of feed slows down the exit flow of the rumen and prolongs the time during which the active ingredient remains there and is absorbed. Consequently it is advisable to reduce the access of animals to feed (especially to fresh pasture, not to water) 24 hours before administration. For the same reason, it is better to keep the animals away from food for about 6 hours after drenching. However sick or weak animals should not be kept away from food and fasting animals should have access to water. In cattle, a fiber-rich diet also increases the bioavailability of fenbendazole.

Fenbendazole active ingredient is a solid compound poorly soluble in water and in drenches it is formulated as a suspension (not as a solution or as an emulsion). A key unfavorable feature of all suspensions is that the suspended solid particles tend to fall down to the bottom of the container and sediment, very much like sand in water. This means that suspensions must be thoroughly shaken before use. How fast the suspension sediments and how easily shaking the container redistributes the suspension depends on the formulation quality. A good formulation sediments slowly and shaking will re-suspend it quickly. Bad formulations sediment quickly and shaking re-suspends them slowly.

Thoroughly shaking suspensions before use is crucial for efficacy. If the active ingredient remains in the sediment, a few animals may get most of the active ingredient and will be overdosed, and the large majority will get almost only solvents and will be underdosed.

Click here for general information on good practices for the prevention and control of gastrointestinal worms in livestock.


This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics. 

Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.

In case of doubt contact the manufacturer or a veterinary professional.