Brand: TOLPENPRO ™ Insecticide Ear-Tag


DELIVERY FORM: «ear-tag» to be applied to the front or back of the ear.


  • Tolfenpyrad: 150%
  • Tag weight: 14 g

CHEMICAL CLASS of the active ingredient(s): pyrazole derivative

INDICATIONS: CATTLE (beef & dairy)

PARASITES CONTROLLED* (spectrum of activity)

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


  • For optimum control of horn flies and face flies, attach two tags per mature animal (one per ear).
  • For adequate control of horn flies and face flies, attach one tag per mature animal.
  • For calves apply one tag per animal (for face fly control). Replace as necessary.
  • Tolfenpro™ is effective against horn flies and face flies for up to five (5) months
  • Use in rotation with pyrethroid, organophosphate or avermectin cattle ear tags
  • Remove tags at the end of fly season or prior to slaughter, whichever comes first.


  • LD50 (acute oral) in rats: for the a.i. 150-386 mg/kg (according to MSDS)
  • LD50 (acute dermal) in rats: for the a.i. >2000 mg/kg (according to MSDS)

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.

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Risk of resistance? LOW. There are so far no reports on resistance of horn flies (Haematobia irritans) to tolfenpyrad.

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it is most probably not due to resistance but to incorrect use, which is usually the most frequent cause of product failure.

However, to prevent development of resistance to this active ingredient rotation with active ingredients having a different mode of action is highly recommended.

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 ear-tags, 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? NO; so far not with the same active ingredient.

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

For an overview on the most used insecticidal EAR TAG brands click here.


TOLFENPRO Insecticide Ear-tag for cattle from BAYER (now ELANCO) is one of the numerous insecticide-impregnated ear-tags for the control of flies on cattle.

Tolfenpyrad is a pyrazole derivative with a broad spectrum of efficacy against insects. It was introduced by MITSUBISHI CHEMICAL in the early 2000s for use in agriculture. To our knowledge this product is the first veterinary product using this active ingredient. Its mechanism of action on the flies is different from that of organophosphates, synthetic pyrethroids and macrocyclic lactones, which makes it a good candidate for rotation programs. Although closely related with phenylpyrazoles (e.g. fipronil) the mechanism of action is different.

Insecticide-impregnated ear-tags are designed to slowly release the insecticide into the animals hair-coat to ensure protection for months. Whether most of the insecticide is released at the beginning and only a little at the end, or release is homogeneous depends on the composition of the matrix and the behavior of the active ingredient(s) in it. However, after 3 to 4 months the amount released progressively decreases to drop below the amount that is required to ensure full fly control. This means that at a certain point flies and other parasites may be exposed to sub-lethal doses, which is generally considered as a factor that favors resistance development. For this reason the tags should be removed after 4-5 months following the manufacturer's use recommendations, and either replaced by new ones or the animals should be left untagged.

Once the active ingredient is released, efficacy strongly depends on the spreading of the active ingredient(s) along the animal's hair coat to other parts of the body. This depends on factors such as solubility of the active ingredient in the hair and skin lipids. Persistence in the hair-coat depends on other features of the active ingredient(s) such as volatility, resistance to sunlight, solubility in water, etc. As a general rule, some body parts will get less active ingredient than other parts and protection there will be lower, e.g. the legs, the underbelly, the udders, below the tail, etc.  Animal behavior (licking, grooming, rubbing, etc.) plays a role as well. It has been shown, that if only half of the animals in a herd are tagged, those untagged will also be protected so some extent against flies, indicating that part of the active ingredient is transferred from tagged to untagged animals. However, this also means that tagged animals will lose part of the active ingredient and protection will be shorter and/or control will be poorer. For this reason all animals in a herd should be tagged because this reduces the impact of animal behavior in efficacy and protection. However, since the individual animal behavior plays a role in efficacy and length of protection, it must be accepted that protection will not always be the same in all the animals in a herd.

Tolfenpyrad is basically a contact insecticide. 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.

After topical administration to livestock or other animals, organophosphates do not have a systemic mode of action, i.e. they are not transmitted to the parasite through the blood or the host.

Control of susceptible (i.e. non-resistant) horn flies is usually excellent, because they spend most of their time on cattle and thus are exposed to the insecticide for a long period of time. And they remain mainly in the back of the animals, where the concentration of the active ingredient released by the ear-tags is rather high. Face flies remain shorter on the hosts and protection may not last as long as that of horn flies.


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.