Brand: TOPDEC Pour-on
PARASITES CONTROLLED* (spectrum of activity)
* Country-specific differences may apply: read the product label.
- Gastrointestinal roundworms (adults & L4 larvae): Ostertagia ostertagi (incl. inhibited larvae), Haemonchus placei, Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus longispicularis, Cooperia oncophora, Cooperia punctata, Cooperia pectinata, Oesophagostomum radiatum, Nematodirus helvetianus, Bunostomum phlebotomum , Trichuris spp.
- Lungworms: Dictyocaulus viviparus (adults & L4).
- Sucking & biting lice: Linognathus vituli, Solenopotes capillatus, Haematopinus eurysternus, Bovicola (Damalinia) bovis.
- Mites (scabies): Chorioptes bovis.
- Buffalo flies: Haematobia irritans exigua.
- Cattle ticks: Rhipicephalus (Boophilus) microplus.
- Residual effect (significant country differences: read the product label!):
- Cattle: 500 mcg/kg bw, equivalent to 1 ml/10 kg (=22 lb) bw
* Can be slightly different in some countries: read the product label!
- LD50 (acute oral) in rats: >5000 mg/kg (estimate)
- LD50 (acute dermal) in rats: 2870 mg/kg (estimate)
- Estimated hazard class according to the WHO: not applicable for veterinary medicines
Suspected poisoning? Read the article on moxidectin safety in this site.
Withholding periods (=withdrawal times) in days for meat & milk (country-specific differences may apply: read the product label)
- Meat: Australia NIL.
- Milk: Australia NIL.
WARNING !!!: Never use on humans, dogs or cats
You may be interested in the following articles in this site dealing with the general safety of veterinary products:
- Safety for humans
- Safety for domestic animals
- Safety for the environment
- Hazard classifications of pesticides
Resistance of gastrointestinal roundworms to macrocyclic lactones in sheep, goats and cattle has been reported in numerous countries. Most cases have been reported for ivermectin, and moxidectin often works well against ivermectin-resistant worms initially. But if moxidectin use continues gastrointestinal roundworms will become resistant to it rather quickly. Based on the very abundant and frequent use of ivermectin and other macrocyclic lactones in livestock (with more-or-less cross-resistance to ivermectin) it must be assumed that resistance of gastrointestinal roundworms to this chemical class will continue spreading and strengthening in the future.
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.
- Benzimidazoles, e.g. albendazole, febantel, fenbendazole, oxfendazole, etc. Similar or even worse resistance problems than ivermectin
- Imidazothiazoles, mainly levamisole. etc. Similar or even worse resistance problems than ivermectin
- Nitroxinil (limited spectrum of activity)
- Tetrahydropyrimidines, e.g. morantel, pyrantel (limited spectrum of activity)
- Salicylanilides, e.g. closantel (limited spectrum of activity)
These alternative products may not be available in all countries, or may not be available as pour-ons.
Resistance of cattle ticks Rhipicephalus (Boophilus) microplus to ivermectin, another macrocyclic lactone has been reported in several Latin American countries. It is not yet a widespread problem, but nevertheless a warning. Based on the intensive use of macrocyclic lactones on cattle it is only a matter of time for resistance of cattle ticks to these compounds to develop elsewhere unless specific resistance preventative measures (e.g. rotation, IPM, etc.) are taken.
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, many brands in some countries (e.g. Australia), rather few, if at all, in other countries (e.g. the EU, USA).
Click here to learn more about GENERIC vs. ORIGINAL drugs.
For an overview on the most used antiparasitic pour-on brands click here.
TOPDEC Pour-on for Cattle is a local brand from AGSURE containing generic moxidectin.
Moxidectin is a macrocyclic lactone introduced in the 1990s (by AMERICAN CYANAMID → FORT DODGE → ZOETIS). It is moderately used in livestock and pets, but not in agriculture. Its spectrum of activity is similar to the one of ivermectin, i.e. basically roundworms and certain external parasites (mites, lice, etc.). As all other macrocyclic lactones moxidectin is not effective against tapeworms and flukes.
Moxidectin is generally considered as more potent than ivermectin against gastrointestinal nematodes of livestock, particularly in sheep and goats, and against a few other livestock pests (e.g. sheep scab, cattle ticks, etc.). It is also less toxic than ivermectin, which makes it possible to use it at higher rates, particularly in long-acting formulations.
But it has also disadvantages. In several scientific studies it has been shown that ivermectin administered as a pour-on is not "automatically" absorbed through the skin. Licking (self licking or licking of other treated animals) may account for >50% of the total intake, compared with only about 10% absorbed directly through the skin. This is the reason why a dose of 500 mcg/kg bw is needed after pour-on treatment, compared with only 200 mcg/kg bw after injection. And it has been also shown that intake of topically administered active ingredient in some cattle may be twice as high as in other ones, all treated at the same rate. The reason is that individual cattle show a different licking behavior. An important practical consequence is that the quantity that is finally ingested and is therefore available for the control of gastrointestinal worms depends on the licking behavior of the treated animals. "High lickers" can be overdosed, whereas "low lickers" can be underdosed. And chronic underdosing of animals in a herd may enhance development of resistance to ivermectin and other macrocyclic lactone in gastrointestinal roundworms.
To our knowledge similar studies have not been carried out with the moxidectin pour-ons, but it must be assumed that the licking-behavior of cattle affects intake of moxidectin in a comparable way. A similar effect of the licking behavior on the intake of active ingredient after pour-on administration has also been shown for fluazuron, a tick development inhibitor.
Absorption through the skin is also negatively affected by the thickness of the skin and the hair coat, by dust and mud on the coat, by product lost on fences and yards, etc, factors that don't play a role after injection.
In contrast with the injectables, the pour-on formulation should not be administered to wet animals, and rain shortly before (up to 6 hours) or after administration can cause product run-off and thus under-dosing. The pour-on shouldn't be administered by strong winds that may blow away part of the product and/or contaminate the workers.
For these reasons efficacy after pour-on administration is usually less reliable than after injection.
Being an excellent antiparasitic, comparable to ivermectin, moxidectin does not control all parasites of livestock. Unfortunately advertising and even the label of some generic formulations in less developed countries often include unsubstantiated claims. To help preventing confusion and misuse it is useful to know that whatever moxidectin pour-on (without additional active ingredients) used at the recommended dose of 500 mcg/kg DOES NOT CONTROL:
- Ticks (e.g. Amblyomma spp, Rhipicephalus spp, Dermacentor spp, Haemaphysalis spp, Hyalomma spp, Ixodes spp, etc.)
- Flies (e.g. houseflies, stable flies, black flies, horse flies, etc.)
- Fleas (e.g. Ctenocephalides spp)
- Tapeworms (e.g. Moniezia spp)
- Flukes (e.g. liver fluke Fasciola hepatica)
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.