Brand: PERMETHRIN E-PRO Insecticide 36.8%


FORMULATION: liquid concentrate for spraying animals or farm premises

ACTIVE INGREDIENT(S): Permethrin: 36.8% = 368 g/L

CHEMICAL CLASS of the active ingredient(s): synthetic pyrethroids


PARASITES CONTROLLED (spectrum of activity)


Beef & Dairy Cattle, Goats & Sheep

  • Against horn flies:
    • High pressure spray: 4 fl. oz. (118 ml) to 50 gals. water (treats 200). Permethrin concentration in final dilution: 230 ppm* = mg/L = 0.023% Active Ingredient. AI. 1 qt. of coarse spray per animal.
  • Against horn flies, face flies, horse & deer flies, housefliesblack flies, stable flies, mosquitoes, mites, lice, tickssheep keds, eye gnats:
    • High pressure spray: 4 fl. oz. (118 ml) to 25 gals. water. (treats 50-100). Permethrin concentration in final dilution: 460 ppm* = mg/L = 0.046% Active Ingredient. 1-2 qt. of coarse spray per animal over whole body surface. For mange, scabies, ticks and lice, thoroughly wet animal. Repeat application 10-14 days for mites and lice.
  • Against horn flies, face flies, stable flieslice, ear-ticks:
    • Low pressure spray (hand pump sprayer): 4 fl. oz. (118 ml) to 2 1/2 gals. water. (treats 64-80). Permethrin concentration in final dilution: 4600 ppm* = mg/L = 0.46% Active Ingredient. For fly and lice control, spray midline from face to tailhead to point of runoff (4-5 fl. oz.) (118-148 ml). For ear tick control, spray directly into each ear (1/2 fl. oz. (15 ml) each).
  • Against horn flies (season-long control), face flies, stable flies:
    • Backrubber self oiler: 4 fl. oz. (118 ml) to 10 gals. diesel oil or suitable mineral oil. Permethrin concentration in final dilution: 1150 ppm* = mg/L = 0.115% Active Ingredient. Keep rubbing device charged. Results improved by daily forced use.


  • Against Northern fowl mites, lice:
    • High pressure spray: 1-4 fl. oz. (30 - 118 ml) to 3.75 gals. water. (treats 375). Permethrin concentration in final dilution: 766 - 3067 ppm* = mg/L = 0.076 - 0.30% Active Ingredient. 1 gal. of coarse spray per 100 birds, paying particular attention to vent area.


  • Against mange, lice:
    • Spray or Dip: 4 fl. oz. (118 ml) to 25 gals. water. (treats 50-100). Permethrin concentration in final dilution: 460 ppm* = mg/L = 0.046% Active Ingredient. Thoroughly wet or dip animals including ears. For Mange, spray pen floors, sides and bedding. Repeat at 14 days.


  • Against horn flies, face flies, horse & deer flies, housefliesblack flies, stable flies, mosquitoes, fleas, mites, lice, ticks, eye gnats:
    • Low Pressure Spray: 0.25 fl. oz. (7.5 ml) to 1 pt. water. Permethrin concentration in final dilution: 5750 ppm* = mg/L = 0.575% Active Ingredient. 1-2 fl. oz. (30-60 ml) spray per animal. Spot treat back, face, legs, tail and ears.
    • Dip Wash: 0.25 fl. oz. (7.5 ml) to 1.25 gals. water. Permethrin concentration in final dilution: 575 ppm* = mg/L = 0.0575% Active Ingredient. Thoroughly wet animal to skin with sponge or rag. Let drip dry.
    • Dip (dogs only): 4 fl. oz. (118 ml) to 20 gals. water. Permethrin concentration in final dilution: 625 ppm* = mg/L = 0.0625% Active Ingredient. Make sure all areas are soaked to skin. Let drip dry on animal. Do not rinse off.


  • Against fleas & ticks:
    • Low Pressure Spray: 0.25 fl. oz. (7.5 ml) to 1 pt. water. Permethrin concentration in final dilution: 5750 ppm* = mg/L = 0.575% Active Ingredient. 1-2 fl. oz. (30-60 ml) spray per animal. Spot treat back, face, legs, tail and ears.
    • Dip Wash: 0.25 fl. oz. (7.5 ml) to 1.25 gals. water. Permethrin concentration in final dilution: 575 ppm* = mg/L = 0.0575% Active Ingredient. Thoroughly wet animal to skin with sponge or rag. Let drip dry.
    • Dip: 4 fl. oz. (118 ml) to 20 gals. water. Permethrin concentration in final dilution: 575 ppm* = mg/L = 0.0575% Active Ingredient. Make sure all areas are soaked to skin. Let drip dry on animal. Do not rinse off.

For off-animal uses read the product label.

* ppm = parts per million


  • LD50 (acute oral) in rats: for the a.i. 400 mg/kg (in oil vehicle, 40:60 cis:trans mixture) to 1350 - 4000 mg/kg (in aqueous vehicle, depending on the study)
  • LD50 (acute dermal) in rats: for the a.i. 4000 mg/kg
  • Estimated hazard class according to the WHO: U, unlikely to present acute hazard

Suspected poisoning? Read the article on permethrin safety in this site.

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

  • Swine Meat: USA Do not ship swine for slaughter within 5 days of last treatment.
  • Milk for human consumption: USA NIL

WARNING !!!: Never use on humans or cats. Permethrin is particularly toxic to cats!

Permethrin and all other 2nd-generation synthetic pyrethroids (e.g. cyhalothrin, cypermethrin, deltamethrin, etc.) are irritant to the eyes and the skin, both of humans and livestock. But irritation is usually worse when using pour-ons than after spraying.

Permethrin and all synthetic pyrethroids (e.g. cyhalothrin, cypermethrin, deltamethrin, etc.) are extremely toxic to fish and aquatic invertebrates. Do not apply directly to water, or to areas where surface water is present, or to intertidal areas below the mean high water mark. Do not contaminate water when cleaning equipment or disposing of equipment washwaters.

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 horn flies, houseflies, fleas, mosquitoes, & poultry mites to synthetic pyrethroids (incl. permethrin) is widespread in the USA and worldwide, and can be very high. Cases of resistance of black flies and stable flies to synthetic pyrethroids (incl. permethrin) have also been reported, but their prevalence is usually low.

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.

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 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: USA
GENERIC BRANDS available? YES, numerous. This brand with generic permethrin is marketed by Y-TEX in the USA.

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 or dipping animals and/or premises containing synthetic pyrethroids for the control of flies, liceticks and other external parasites. Worldwide there are hundreds if not thousands of such products. Besides permethrin, numerous other synthetic pyrethroids are used wordlwide in such products, e.g. cyhalothrin, cypermethrin, deltamethrin, etc. They all have a similar spectrum of activity and a comparable safety profile.

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 more effective active ingredients for the control of external parasites are often not available as concentrates but only as ready-to-use pour-ons, injectables, or in the form of insecticide-impregnated ear-tags. They are usually 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 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 (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 administration to livestock or other animals, 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 in meat and milk.

For best results it is very important to ensure a complete coverage of the animals' hair coat. This is best achieved after dipping the animals. Best alternative to dipping is high pressure spraying (depending on size and hair coat, adult cattle need 3 to up to 10 liters product for complete wetting). Efficacy after hand spraying or spot application are 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 spraying cattle and other livestock click here.

Backrubbers have and inherent weakness: Dosing depends on the behavior of the animals. It is unavoidable that some animals get too much product, and other animals not enough. Besides insufficient protection of some animals, this may cause excessive residues in other animals. For these reasons backrubber application is no more allowed in many countries (e.g. the EU, Australia, etc.). And it is generally accepted that underdosing of animals favors resistance development. To learn more about backrubbers for cattle click here.

Control of susceptible (i.e. non-resistant) horn flies is usually good, because they spend a lot of time on cattle and thus are exposed to the insecticide for a long period of time. Lice are also exposed to insecticides for a long period of time because they never leave the host. Control of face flies is often not as good, due to their different behavior: they do not spend a lot of time on the animals and visit mainly body parts in the face that are humid with body fluids (eyes, nostrils, around the mouth), where the insecticide concentration is diluted by these body fluids. Stable flies, horse fliesblack flies and mosquitoes may bite the treated animal anywhere in its body and remain attached and thus exposed to the insecticide only during their blood meals that last a few seconds or minutes, which is often too short to kill them. Ticks attaching to the hosts in those body parts that are poorly covered with insecticide are also likely to survive.

Most lice and mites species spend their whole life on the infected animals but are likely to survive hidden inside the ears if they are not properly treated. And their eggs remain unaffected by the insecticide: this is why it is very important to re-treat the animals after 2-3 weeks, when most of the eggs laid before the previous treatment have already hatched.

The permethrin strength that results in the final dilution for a particular use is often substantially different for the numerous similar products in the market. E.g. whereas for spraying poultry against mites one manufacturer recommends a dilution that results in a concentration of 1000 ppm (parts per million) permethrin in the spraying liquid, the recommendations of another manufacturer result in a concentration of 500 ppm in the spraying liquid. Both recommendations will provide control of the mites, but control and length of protection at 1000 ppm will be certainly better than at 500 ppm.

All synthetic pyrethroids have a certain repellent effect, mainly on mosquitoes but it lasts usually only a few days, if at all.

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". Permethrin has 4 isomers, 2 cis, and 2 trans. Manufacturers of active ingredients usually supply the raw material in standard qualities, for permethrin typically in a 25/75 or 40/60 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 40/60 mixture is more potent than a cis/trans 25/75 mixture. Qualities with a high 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. If a manufacturer does not disclose the cis/trans ratio of the active ingredient used in its products it may be confusing because he may be selling the "same" product as another manufacturer, but the use recommendations are different.


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.