Brand: ZAPP ® ENCORE ® Pour-on for Sheep


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.

  • Knockdown and long term control of body lice Bovicola (Damalinia) ovis on all breeds of sheep.
  • Treatment and protection against blowfly strike (including Lucilia cuprina) on coarse wool breeds of sheep breeds.


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

Use recommendations (New Zealand):

Lice Control
Body Weight Dose Vol. (mL) Coarse wool: Off-shears only Dose Vol. (mL) Fine-wool: Off-shears only Coarse wool: up to 6 months wool
Up to 7 kg 6 mL 6 mL
7.1 - 10 kg 7 mL 10 mL
10.1 - 20 kg 8.5 mL 12 mL
20.1 - 30 kg 10.5 mL 15 mL
30.1 - 55 kg 13.5 mL 20 mL
55.1 - 75 kg 17 mL 25 mL
> 75 kg 3 mL / 10 kg 5 mL / 10 kg
Apply in a single strip down the middle of the back between the poll and the butt of the tail.
Flystrike Control
Body Weight Dose Volume (mL)
Up to 7 kg 2 x 3 mL
7.1 - 10 kg 2 x 5 mL
10.1 - 20 kg 2 x 6 mL
20.1 - 30 kg 2 x 7.5 mL
30.1 - 55 kg 2  x 10mL
55.1 - 75 kg 2 x 12.5 mL
> 75 kg 1 x 2.5 mL / 10 kg
Appy half dose in a single strip from the poll to the tail base and half dose in a second stroke around the crutch.

* Read the product label for further details on dosing and administration.


  • LD50 (acute oral) in rats: >5000 mg/kg (source: MSDS)
  • LD50 (acute dermal) in rats: >5000 mg/kg (source: MSDS)
  • Estimated hazard class of the a.i. according to the WHO classification of pesticides: U, unlikely to present acute hazard in normal use.

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


Risk of resistance in BODY LICE? YES. Resistance reported in Australia in field populations.

  • New Zealand. To our knowledge there are no confirmed reports on body lice resistance to triflumuron or other benzoylphenyl ureas in New Zealand, but based on the abundant use of this chemical classes and the experience in Australia the risk that it develops is real. The concomittant use of imidacloprid in this product may control lice that have become resistant to triflumuron, since so far no resistance of body lice has been reported to imidacloprid.

Alternative chemical classes/active ingredients for product rotation to prevent resistance of body lice to triflumuron:

These alternative products may not be available in all countries, or may not be available as pour-ons.

Risk of resistance in BLOWFLY STRIKE? YES. Resistance widespread and high in Australia, reported in New Zealand in field populations.

  • New Zealand. Resistance of blowflies to triflumuron has been reported in several field strains of L. cuprina in New Zealand, but it seems not to be as widespread and high as it is in Australia.  For this reason efficacy of this product against blowfly strike may not achieve the label claims. The imidacloprid in the formulation is not effective against blowfly strike.
  • It is interesting to know that benzoylphenyl ureas show cross-resistance with organophosphates (e.g. diazinon), a chemical class that was massively used on sheep in the past against blowfly strike in Australia and New Zealand, now vastly replaced by less toxic compounds.

Alternative chemical classes/active ingredients for product rotation to prevent resistance of blowfly strike to triflumuron:

These alternative products may not be available in all countries, or may not be available as pour-ons.

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.

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? NO, in most countries 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.


ZAPP ENCORE Pour-on for sheep is an original product from BAYER niw ELANCO) for body lice and blowfly strike control. It combines two active ingredients: triflumuron that is effective against both lice and blowfly strike, and imidacloprid that is only effective against lice but with a mode of action different from the one of triflumuron.

Imidacloprid is a neonicotinoid insecticide introduced by BAYER in the early 1990s. As most other neonicotinoids it is a non-systemic contact insecticide, effective against a number of insect pests such as lice, fleas and flies. It has no acaricidal efficacy, i.e. it does not affect ticks or mites. It has no effect whatsoever on internal parasites (roundworms, tapeworms, flukes, etc.). It is abundantly used in pets against fleas, but rather scarcely in livestock. It is vastly used in pesticides for crop protection and for the control of public and household pests (cockroaches, termites, etc.). It is also vastly used in dogs and cats for flea control in pets.

Triflumuron is a broad-spectrum insect growth regulator (IGR) belonging to the benzoylphenyl-ureas introduced in the 1980s (by BAYER). It is effective against immature stages (larvae, nymphs, etc.) of numerous insects but not against adult stages. It is ineffective against ticks or mites. It is moderately used in sheep and scarcely in horses against body lice but not in other livestock or pets. It is also used moderately against agricultural and household pests.

It is important to understand that insect growth regulators do not kill adult lice that may infect sheep at the moment of treatment, i.e. they don't have a knock-down effect. What they do is to prevent development of immature stages. Larvae and/or nymphs fail to molt to the next stage and die. Therefore they are used to prevent the further development of immature stages or eggs of occasional adult lice that sheep may catch. Imidacloprid is a classic insecticide that will rather quickly kill lice adults, nymhs and larvae.

Triflumuron and other benzoylphenyl ureas conquered the sheep body lice market very quickly in Australia and New Zealand in the 1990s after resistance to synthetic pyrethroids exploded and organophosphates that still worked well were progressively withdrawn for safety reasons. In the meantime lice resistance in Australia and New Zealand is a serios issue and increasing.

It is interesting to know that neither triflumuron nor other benzoylphenyl ureas are used on sheep in the EU, the US or in Latin America, where body lice is also an important pest of sheep. The likely reason is that organophosphates and/or synthetic pyrethroids are still widely used in these countries against this pest that has not yet become resistant to these chemicals.


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.