FARNAM MECWORMA & BOT wormer PASTE for HORSES - INTERNATIONAL ANIMAL HEALTH PRODUCTS - abamectin, macrocyclic lactone

Brand: FARNAM ® MECWORMA ® & BOT

Company: INTERNATIONAL ANIMAL HEALTH PRODUCTS

FORMULATION: «oral paste» in pre-charged syringes

ACTIVE INGREDIENT(S): Abamectin: 3.64 mg/g (=0.364%)

CHEMICAL CLASS of the active ingredient(s): macrocyclic lactone

INDICATIONS

HORSES

PARASITES CONTROLLED* (spectrum of activity)

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

RECOMMENDED DOSE*

*Can be slightly different in some countries: read the product label!

  • ~200 mcg abamectin/kg bw equivalent to 5.5 g of paste per 100 kg bodyweight.
  • The contents of one 33 g syringe are sufficient to treat one horse of 600 kg bodyweight. The plunger is calibrated in 100 kg increments which each deliiver 5.5 g oif paste.

SAFETY

  • LD50 (acute oral) in rats: ~2700 mg/kg (estimate calculated according to the WHO based on the abamectin LD50)
  • Estimated hazard class according to the WHO: not applicable for veterinary medicines

Suspected poisoning? Read the articles on abamectin safety and/or morantel safety in this site.

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

  • MEAT & OFFAL: AUS: DO NOT USE LESS THAN 28 DAYS BEFORE SLAUGHTER FOR HUMAN CONSUMPTION.
  • MILK: Do not use in animals producing milk for human consumption

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:

RESISTANCE PREVENTION

Risk of resistance? YES

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 gastrointestinal roundworms through product rotation:

These alternative products may not be available in all countries, or may not be available as oral pastes or gels.

Learn more about resistance and how it develops.

MARKETING

Are the active ingredients of this product ORIGINAL* or GENERICS**?

  • 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 product is marketed: Australia, New Zealand
GENERIC BRANDS available? YES

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

COMMENTS

This product is a classic oral paste for horses from INTERNATIONAL ANIMAL HEALTH PRODUCTS with generic abamectin.

Abamectin, a veteran endectocide introduced in the 1980s (by MSD AgVet → MERIAL), is considered as the "cheap" macrocyclic lactone. It is less potent and more toxic than ivermectin and other macrocyclic lactones but is often "good enough", with a similar spectrum of activity as ivermectin. Interestingly abamectin is widely used on livestock and horses in Australia and New Zealand but so far not in the EU, the USA and Canada. As for other macrocyclic lactones, abamectin has no efficacy whatsoever against tapeworms and flukes.

Most macrocyclic lactones have about two weeks residual effect on horses because they are stored in body fat and progressively released. This, together with the time that worms need to develop inside the horse after infection (pre-patent period) allows to space the treatment intervals to 10 to 12 weeks in year-round control programs in many regions. For other active ingredients that have no residual effect such as fenbendazole, mebendazole, or pyrantel the treatment interval is usually 4 to 6 weeks.

Whereas in ruminants abamectin administered at 200 mcg/kg controls a series of external parasites as well (mites, lice, etc.), such an indication is not approved in most countries in horses: external parasites have to be controlled with ectoparasiticides (e.g. pour-ons, sprays, etc.).

Many horse owners complain about the price of the oral pastes & gels for horses (with ivermectin or other macrocyclic lactones), compared with the much cheaper injectables for livestock with the same active ingredients, used at the same dose (200 mcg/kg). This is why off-label use of livestock ivermectin injectables in horses is very common worldwide, particularly in working horses of cattle and sheep ranches. The reason why injectables are mostly not approved for use on horses is apparently that, shortly after introduction, it was noticed that horses were more prone to develop severe clostridial infections at the injection site (due to contamination of the needles) and other undesired side effects than cattle or sheep. In addition, the pharmacokinetic behavior of ivermectin on horses is different than in ruminants. For these reasons oral pastes were developed for horses that do not show such side effects. However, in numerous countries (e.g. in Latin America) some ivermectin injectables for livestock are also approved for use on horses.

For an overview and a list of the most used oral paste & gel brands click here. 

DISCLAIMER

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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