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Company: ASPEN

FORMULATION: «pour-on» for topical administration.


  • Permethrin: 7.4% = 74 g/L
  • Piperonyl butoxide (=PBO): 7.4% = 74g/L

CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED (spectrum of activity)




Lactating and non-lactating dairy cattle, beef cattle, calves

  • For moderate fly control apply 1.5 ml /100 lbs bw of animal up to a max. of 15 mL per animal. For lice and severe horn fly control apply 2.0 mL/100 lbs bw, up to a maximum of 20 mL per animal. Pour-on: pour correct dose along back and down face. Ready-to-use-spray: Use undiluted in a mist sprayer to apply correct dose. Back Rubber Use: Mix 64 mL (2.1 oz.) per gallon of mineral oil. Keep rubbing device charged. Results improved by daily forced use.

Sheep & lambs

  • Sheep keds & lice: Pour-On: Pour along the back. Apply 1 mL per 50 lbs. body weight of animal, up to maximum of 12 mL for any one animal. For optimum control, all animals in the flock should be treated after shearing.
  • Biting midges: Ready-To-Use Spray: Use undiluted in a mist sprayer to apply 4 mL of product per animal to the ventral (underside) of sheep.
  • Repeat treatment as needed, but not more than once every two weeks. For optimum lice control, two treatments at a 14-day interval are recommended.

Horses & foals

  • Wipe on: Apply 8 ml to 16 ml as a wipe on. Dampen an applicator mitt, cloth or toweling (Turkish) with this product. Rub over hair with special attention to the legs, shoulders, neck and facial areas where flies tend to congregate. Be especially careful not to get in horses eyes.
  • Ready-To-Use spray: Use this product after riding or exercise. Use undiluted in a mist sprayer, applying 8 ml to 16 ml per animal. Apply directly onto attached ticks.


  • Pour on: After riding or exercise, pour 8 ml to 16 ml of this product along the back and down the face of MATURE horses, being careful to avoid the eyes. Do not use this method of application on foals.


  • In & around horse, beef, dairy, swine, sheep & poultry premises, animal hospital pens & kennels, and "outside" meat processing premises.
  • Ready-To-Use Spot or Premise Spray: Use undiluted in a mist sprayer. Apply directly to surface to leave a residual insecticidal coating, paying particular attention to areas where insects crawl or alight. 500 mL will treat approximately 7,200 square feet.


  • LD50 (acute oral) in rats: >5050 mg/kg (according to MSDS)
  • LD50 (acute dermal) in rats: >2020 mg/kg (according to MSDS)
  • 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)

  • Meat: USA NIL
  • Milk for human consumption: USA NIL

WARNING !!!: Never use on humans, dogs 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. 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 horn flies, houseflies, and mosquitoes 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.

The synergist in the formulation (PBO) is supposed to neutralize resistance. However, PBO works only against the so-called metabolic resistance (enhanced detoxification) caused by mixed function oxidases (= MFO), which is one among several mechanisms by which parasites can become resistant to synthetic pyrethroids and pesticides of other chemical classes. PBO specifically inhibits the activity of MFOs. If metabolic resistance is caused by other enzymes than MFOs, or if resistance is (also) due to other mechanisms such as target site insensitivity, reduced penetration or behavioral modifications, it won't be neutralized by PBO. In the vast majority of cases producers affected by parasites resistant to synthetic pyrethroids do not know which mechanism makes the parasites resistant, and it is mostly not possible to find it out. Consequently, whether the synergist PBO helps to overcome resistance or not is in fact a lottery.

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

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

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


EXIT GOLD SYNERGIZED Pour-on is one of numerous insecticidal pour-ons for cattle, sheep and other livestock containing synthetic pyrethroids for the control of flies, liceticks and other external parasites. Worldwide there are hundreds if not thousands of such pour-ons. Besides permethrin, numerous other synthetic pyrethroids are used in such pour-ons, e.g. cyhalothrin, cypermethrin, deltamethrin, etc. They all have a similar spectrum of activity and a comparable safety profile.

Permethrin is one of the first Type-II synthetic pyrethroids introduced already in the 1970s by several companies (FMC, ICI, SHELL, etc.). It is massively used in veterinary products as well as in agricultural and hygiene pesticides.

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.

All pour-ons containing contact insecticides such as synthetic pyrethroids have the same weakness: they are applied on the back of the animal and spread more or less quickly along the hair coat to other parts of the body, but coverage is usually not homogeneous and some parts of the body are not or only poorly reached. How fast and complete the spreading is depends on a lot of factors (e.g. distance to the delivery point, rain, animal behavior such as grooming, licking, rubbing, etc.) but also on the inert ingredients in the formulation, which may or may not favor spreading. In any case, compared with the backline the concentration of the active ingredient will be significantly lower in body parts that are difficult to reach (e.g. udders, perineum, below the tail, inside the ears, etc), where parasites can survive because the concentration is not high enough to kill them. For this reason such pour-ons are mostly not effective enough against some parasites such as ticksfleas and mites. Irregular spreading may also cause chronic exposure of some parasites to sub-lethal doses, which is known to favor development of resistance.

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.

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 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. 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.

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