Company: VIRBAC

DELIVERY FORM: «drench» for oral administration.


  • Fenbendazole 25.0 g/L (equivalent to 2.5%)
  • Levamisole hydrochloride 40.0 g/L (equivalent to 4%)
    • Selenium 0.5 g/L (equivalent to 0.05%): without anthelmintic efficacy

CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED (spectrum of activity)


  • Effective against sensitive and single-resistant mature and immature stages of the roundworms and lungworms listed below and to aid in the control of tapeworms and selenium deficiencies in sheep and lambs:Barber's pole worm (Haemonchus contortus), small brown stomach worm (Teladorsagia=Ostertagia spp), black scour worm (Trichostrongylus spp), small intestinal worm (Cooperia spp), thin necked intestinal worm (Nematodirus spp), intestinal threadworm (Strongyloides papillosus), hookworm (Bunostomum spp), nodule worm (Oesophagostomum spp), large mouthed bowel worm (Chabertia ovina), large lungworm (Dictyocaulus filaria).
  • Aids in the control of tapeworm (Moniezia expansa).


  • 1ml product per 5 kg body weight, equivalent to 5 mg/kg fenbendazole and 8 mg/kg levamisole hydrocloride
Bodyweight (kg) Dose (mL) 20 L treats
<15 3 6666
16-20 4 5000
21-25 5 4000
26-30 6 3333
31-35 7 2857
36-40 8 2500
41-45 9 2222
46-50 10 2000
51-55 11 1818
56-60 12 1666
61-65 13 1538
66-70 14 1428
>70 1 ml/5kg  

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


  • LD50 (acute oral) in rats:
    • Fenbendazole: >10000 mg/kg (for the a.i.)
    • Levamisole: 180 mg/kg (for the a.i.)

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

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

  • Meat: 14 days
  • Milk for human consumption: 3 days
  • ESI: 14 days

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


Risk of resistance? YES

Unfortunately, resistance of several gastrointestinal roundworms to fenbendazole (and other benzimidazoles) and levamisole is already very high and very frequent worldwide in sheep and goats. Double (i.e. simultaneous) resistance to both chemical classes is also possible. Most affected worm species are:

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

It is generally accepted that the use of mixtures of active ingredients with different modes of action can delay the appearance of resistance. But only if the concerned parasites are susceptible to all the actives in the mixture. If not, the mixture is likely to promote multi-resistant parasites, because the selection pressure against all actives remains in place. Mixtures such as this one may provide peace-of mind to those users that do not know the resistance status of worms in their property: probably one of the actives will work... This may be the case for a while. But the risk that some worm species become resistant to all components after a few years using the same or comparable mixtures is considerable. If it is not too late, a better alternative is to determine the resistance status in the property and to rotate among products (not mixtures) against which the worms have not yet developed resistance, stopping the use of those chemical classes that have already shown resistance problems.

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.

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**?

  • Fenbendazole: GENERIC (introduced in the 1970s)
  • Levamisole: GENERIC (introduced in the 1960s)

*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: Australia, New Zealand
GENERIC BRANDS available? YES. This product tself is a combination o generic active ingredients.

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

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


DUOCARE plus Selenium is a drench brand from VIRBAC combining 2 generic anthelmintic active ingredients with different modes of action against gastrointestinal worms of sheep: fenbendazole and levamisole hydrochloride.

Fenbendazole is a veteran anthelmintic introduced in the 1970s (by HOECHST). It shows broad-spectrum efficacy 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 massively used in livestock and horses worldwide, much less in pets.

Levamisole is another veteran anthelmintic introduced by JANSSEN already in the 1960s (NILVERM, RIPERCOL). It shows broad-spectrum efficacy against roundworms (gastrointestinal and pulmonary) but no efficacy whatsoever against tapeworms and flukes. It is also completely ineffective against external parasites of livestock (ticksflies, lice, mites, etc). Levamisole has been used massively worldwide in countless generic formulations. It still remains one of the most preferred low-cost anthelmintics for livestock worldwide. It is less used in pets.

Fenbendazole and levamisole administered as a drench have no residual effect, i.e. they kill the parasites shortly after administration, but do not significantly protect the animals against re-infestation by infective stages in their environment.

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.

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.