Brand: BLOCKADE ® S Cattle Dip & Spray

Company: COOPERS

FORMULATION: liquid concentrate for dipping and spraying animals


CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED (spectrum of activity)


1:250, i.e. 1 part of product in 250 parts water, equivalent to 100 ppm* cypermethrin and 552 ppm* chlorfenvinphos,
Stirring Plunge dip: Hand stir the dip with a paddle. Do not use cattle as stirrers.
Spray race: Agitate vigorously with a pump and manually with a paddle. It is essential that the dip/sump is stirred at the beginning of each day's dipping.
Topping up / Replenishment Plunge dip: When the level of the dip has fallen by 1000 litres, topping up should be carried out. Add 1 part product to 185 parts of water (1:185) and stir as above. It is not advisable to allow the dip volume to fall more than 1000 litres from the original level.
Spray Race: When the supm level has dropped 300 litres, topping up should be carried out. Add 1 part product to 185 parts of water (1:185) and stir sump as above. It is not advisable to allow the dip volume to fall more than 300 litres from the original level. When wash is polluted, clean out sump before recharging.
Management It is important that the product be used at the recommended concentration. This will be achieved by charging and topping up as described above. If the level of wash is allowed to fall excessively without topping up, the concentration of the product will fall and its efficacy will be reduced.
Reinforcement Not recommended.
Hand Spray and non-recirculating Spray Races
Cattle only 1:250, i.e. 1 part of product in 250 parts water, equivalent to 100 ppm* cypermethrin and 552 ppm* chlorfenvinphos.

 * ppm = parts per million = mg/L

Read the complete product label carefully and ensure thorough accomplishment of all the use instructions.


  • LD50 (acute oral) in rats:
    • Chlorfenvinphos a.i. 9.6 to 39 mg/kg
    • Cypermethrin a.i. 250 (oily vehicle) to 5150 mg/kg (aqueous vehicle)
  • LD50 (acute dermal) in rats:
    • Chlorfenvinphos a.i. 30 - 108 mg/kg
    • Cypermethrin a.i. >4920 mg/kg
  • Estimated hazard class according to the WHO: II, moderately hazardous

Suspected poisoning? Read the article on cypermethrin safety and chlorfenvinphos safety in this site.

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

  • Meat
    • Cattle, goats: AUS 8 days
    • Horses: AUS 28 days
  • Milk for human consumption: AUS Do not use on lactating cows or within 42 days of calving, where milk or milk products may be used for human consumption. Do not use on female sheep or goats that are producing or may in the future produce milk for human consumption.

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

All synthetic pyrethroids (e.g. cyhalothrin, cypermethrin, deltamethrin, permethrin, etc.) are extremely toxic to fish and aquatic invertebrates. Do not contaminate dams, streams or waterways with product or used containers. Store original container, tightly closed in a safe place under lock and key. All organophosphates (incl. chlorfenvinphos) are highly toxic to birds.

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 cattle ticks (Rhipicephalus = Boophilus microplus) and buffalo flies (Haematobia irritans exigua) to synthetic pyrethroids is widespread in AUS and elsewhere and can be very high. Resistance of both parasites to organophosphates has also been reported in Australia but is usually less high and frequent than to synthetic pyrethroids. Multi-resistant cattle ticks, i.e. simultaneously resistant to both organophosphates and synthetic pyrethroids have been also reported in Australia and elsewhere.

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, although this is usually the most frequent cause of product failure.

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 for dipping or spraying, 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: Australia
GENERIC BRANDS available? YES, with comparable mixtures of synthetic pyrethroidsorganophosphates. This brand is marketed by COOPERS in Australia.

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

For an overview on the most used antiparasitic spray, dip & dust BRANDS click here.


This product is one of the numerous liquid insecticides for spraying animals for the control of ticks and flies. Worldwide there are hundreds if not thousands of such products. Besides cypermethrin, numerous other synthetic pyrethroids are used worldwide in such products, e.g. cyhalothrindeltamethrin, flumethrin, fenvaleratepermethrin, etc. They all have a similar spectrum of activity and a comparable safety profile. Mixtures of synthetic pyrethroids and organophosphates such as the one in this brand are less frequent.

Cypermethrin is one of several veteran type-II synthetic pyrethroids. It was introduced by ICI & SHELL in the 1970s. Worldwide it is massively used in veterinary products as well as in agricultural and hygiene pesticides.

Chlorfenvinphos is a veteran broad-spectrum organophosphate introduced in the 1950s by SHELL (SUPONA) and CIBA-GEIGY (STELADONE) that has been abundantly used worldwide in agriculture and veterinary insecticides. Nowadays usage on livestock and dogs is rather scarce. Chlorfenvinphos is highly effective against flies and ticks, but used as indicated in the label of this product is not effective against ticks.

Insecticide concentrates for spraying and dipping such as this product often represent the cheapest option for insect control on animals. However the active ingredients used in such products are mostly rather old (introduced in the 1950s to 1970s) and many pests have developed resistance to them. More modern and often more effective active ingredients for the control of external parasites are often not available as concentrates but only as ready-to-use pour-ons and  injectables. They are often more effective, more convenient and with a longer protection period than the concentrates, but are also more expensive and often not approved for the control of as many pests as the concentrates.

All synthetic pyrethroids and organophosphates are veteran pesticides developed in the 1950s-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 (i.e. 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.

After topical administration to livestock or other animals, both organophosphates and synthetic pyrethroids do not have a systemic mode of action, i.e. they are not transmitted to the parasite through the blood or the host. Topically administered synthetic pyrethroids are very poorly absorbed through the skin of the hosts, and what is absorbed is quickly broken down and/or excreted. Consequently the concentration reached in the blood is too low to kill blood-sucking parasites. But this is why they are considered rather safe for mammals, both humans and livestock (cats are an exception: pyrethroids are toxic to them!) and why they leave rather low residues.

For best results it is very important to ensure a complete coverage of the animals' hair coat (depending on hair coat adult cattle may need 3 to up to 10 liters product for complete wetting). This is best achieved after dipping the animals. Best alternative to dipping are spray races. Efficacy after hand spraying is often poor due to the fact that using these methods some parts of the body may not be properly treated (e.g. inside the ears, below the tail, the udders, etc.), which allows a significant number of parasites to survive, reproduce and perpetuate the infestations. To learn more about correctly dipping or spraying cattle and other livestock read the corresponding articles on dipping and spraying livestock in this site.

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". Cypermethrin has 8 isomers, 4 cis and 4 trans. Manufacturers of active ingredients usually supply the raw material in standard qualities, for cypermethrin typically e.g. in a 40:60, 50:50 or 80:20 cis:trans ratio. It happens that the efficacy against parasites and the mammalian toxicity of these isomers are significantly different. Typically cis isomers are more effective insecticides but also more toxic to mammals. Obviously a cis/trans 80:20 mixture is more potent than a cis/trans 40:60 mixture. Qualities with higher cis content are usually also more expensive. And the higher the percentage of the most active isomer, the lower the rate that is required for achieving the same efficacy.


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.