FORMULATION: «pour-on» for topical administration.


CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED* (spectrum of activity)

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

  • Treatment and prevention of infestations by:
  • Provides up to 13 weeks protection against lice.


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

  • FLYSTRIKE PREVENTION AT DOCKING: Apply 11 ml product per lamb as an arc.
  • FLYSTRIKE PREVENTION AND LICE CONTROL: Apply the recommended dosage as 2 stripes plus a third stripe as an arc (as per the breach diagram).
  • LICE CONTROL ONLY: Apply the recommended dosage as 2 stripes, eg 31-40 kg live-weight = a total of 27 ml along the backline from poll to tail.
  • For optimum results treatment is recommended when wool is as short as possible.
  • Existing flystrike at the time of application must be treated with a conventional blowfly dressing.

Read the product label for further details on dosing.


  • LD50 (acute oral) in rats:
    • deltamethrin: 31-5000 mg/kg depending on the carrier (for the a.i.)
    • diflubenzuron: >4640 mg/kg (for the a.i.)
  • Estimated hazard class according to the WHO: III, slightly hazardous

Suspected poisoning? Read the article on deltamethrin safety in this site. Diflubenzuron is an IGR with rather low mammalian toxicity.

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

  • Meat: New zealand: 3 days
  • Milk for human consumption: New Zealand: Milk intended for sale for human consumption must be discarded during treatment and for not less than 35 days following the last treatment.
  • Wool: New Zealand: 2 months.

WARNING !!!: Never use on humans, dogs or cats. Synthetic pyrethroids are toxic to cats!

2nd-generation synthetic pyrethroids (e.g. cyhalothrin, cypermethrin, deltamethrin, permethrin, etc.) are irritant to the eyes and the skin, both of humans and livestock. The inert ingredients in the formulation may worsen this side effect. Irritation can be particularly problematic for dairy cows because it can significantly hinder handling for milking.

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 body lice (Bovicola = Damalinia ovis) to synthetic pyrethroids is widespread in Australia and has been reported in New Zealand too. The same applies to resistance of blowfly strike to diflubenzuron and other benzoylphenyl-ureas.

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 against a given parasite 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 the parasites in their property: at least one of the actives will work... This may be the case for a while. But the risk that some parasites 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 external parasites through product rotation:

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

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: New Zealand.
GENERIC BRANDS available? YES, but rather few with this particular composition.

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

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


This product is an classic pour-on for sheep from RAVENSDOWN but with a rather unusual combination of deltamethrin (mainly lousicide) and diflubenzuron, an insect growth regulator effective against lice and blowfly strike.

Deltamethrin is a last-generation synthetic pyrethroid introduced in the late 1970s (BUTOX by ROUSSEL-UCLAF → INTERVET → MSD ANIMAL HEALTH). It has a broad-spectrum of activity against insects, ticks and mites. During the last decades of the last century it has been very much used against agricultural, domestic and veterinary pests. Nowadays usage has declined because numerous pests (e.g. cattle ticks, horn & buffalo flies, houseflies, sheep body lice, fleas, mosquitoes, cockroaches, etc.) have developed resistance to most synthetic pyrethroids (incl. deltamethrin).

All synthetic pyrethroids are veteran pesticides developed in the 1970s-1980s and are basically contact insecticides. This means that when the parasite comes in contact with it (e.g., during the blood meal, after landing on a treated host, etc), the active ingredient that impregnates the host's hair coat penetrates through the cuticle of the parasite (the "skin" of insects and other arthropods) into its organism and disturbs essential biological processes in the parasite's body, in this case its nervous system.

It is useful to know that the active ingredients of many synthetic pyrethroids consist in a mixture of various optical isomers, typically those called "cis", and those called "trans", which have different efficacy and toxicity. Deltamethrin is an exception to this because it consists of a single isomer.

Diflubenzuron is a veteran IGR, the first benzoylphenyl-urea, discovered already in the 1970s (by PHILIPS-DUPHAR). It is a so-called Chitin Synthesis Inhibitor (CSI) effective against numerous insect species. It is moderately used in sheep, very scarcely in other livestock but not in pets. It is also moderately used in agricultural pesticides. It was introduced for use as a lousicide in sheep in Australia only in the 1990's (under the TM FLEECARE from HOECHST), when lice developed high resistance to synthetic pyrethroids, which lost approval for lice control. Diflubenzuron and other benzoylphenyl-ureas subsequently conquered the sheep body lice market very quickly in Australia after resistance to synthetic pyrethroids exploded and organophosphates that still worked well were progressively withdrawn for safety reasons.

Chitin is a component of the cuticle of insects, which is an essential part of their outer skeleton. If chitin is not properly produced, larvae die when they attempt the next molt. The consequence is that fly maggots cannot complete molting and die. CSIs such as the benzoylphenyl ureas (BPUs, e.g. diflubenzuron, triflumuron) inhibit chitin synthesis. But they do not immediately kill the fly maggots (larvae), i.e. they have no knockdown effect. Larvae will die at their next attempt to molt to the next developmental stage, which may take 1-4 days to occur, depending on age of the maggots at the time of treatment, humidity, temperature, etc. For this reason, IGRs are usually not used for curing established strikes, but for preventing their development by killing the very small first-stage larvae that hatch out of the eggs deposited by the adult flies on the wool.


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.