Brand: QUEST ® EQUINE GEL
FORMULATION: «oral gel» in pre-charged syringes
ACTIVE INGREDIENT(S): Moxidectin 20 mg/g (= 2%)
CHEMICAL CLASS of the active ingredient(s): macrocyclic lactone
HORSES & PONIES
PARASITES CONTROLLED* (spectrum of activity)
* Country-specific differences may apply: read the product label.
- Large strongyles: Strongylus vulgaris (adults and arterial stages); Strongylus edentatus (adults and visceral stages); Triodontophorus brevicauda (adults), Triodontophorus serratus (adults).
- Small strongyles: Adult and immature (fourth stage larvae) small strongyles or cyathostomes: Cyathostomum spp, Cylicocyclus spp, Cylicostephanus spp,
Cylicodontophorus spp, Gyalocephalus spp. EQUEST Oral Gel is effective against undifferentiated lumenal larvae and agaisnt encysted late L3 and L4 mucosal cyathostome larvae.
Pinworms (adults and L4 larval stages): Oxyuris equi
- Ascarids (adults and L4 larval stages): Parascaris equorum
- Hairworms (adults):Trichostrongylus axei
- Large-mouth stomach worms (adults): Habronema muscae
- Stomach bots: Oral and gastric stages of Gasterophilus spp, horse bot flies
*Can be slightly different in some countries: read the product label!
- 0.4 mg moxidectin per kg bodyweight (= 400 mcg/kg).
- The syringe is calibrated in 50-pound increments, up to 1150 pounds
- LD50 (acute oral) in rats: >5000 mg/kg (estimate calculated according to the WHO based on the moxidectin LD50)
- Estimated hazard class according to the WHO: not applicable for veterinary medicines
Suspected poisoning? Read the articles on moxidectin safety in this site.
Withholding periods (=withdrawal times) for meat & milk (country-specific differences may apply: read the product label)
- MEAT & OFFAL: USA: Do not use in horses intended for human consumption.
- MILK: Do not use in animals producing milk for human consumption
WARNING !!!: Never use on humans, dogs or cats
Risk of resistance? YES
- Small strongyles (cyathostomes). Tolerance of small strongyles to macrocyclic lactones (e.g. ivermectin, moxidectin), manifested as a low but significant worm egg output after treatment (determined after fecal egg counts) is not yet widespread, but has been already reported in Europe (e.g. in the UK, Germany, Italy), the USA, and Brazil.
- Parascaris equorum: Resistance to macrocyclic lactones (e.g. ivermectin, moxidectin) has been reported in the USA, UK and Australia.
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:
- Benzimidazoles, mainly fenbendazole, mebendazole, etc. But they also have similar or even worse resistance problems than macrocyclic lactones
- Imidazothiazoles, mainly levamisole. Not approved for use in horses in many countries.
- Tetrahydropyrimidines, mainly pyrantel (limited spectrum of activity), but resistance cases have also been reported (e.g. Australia, USA, Brazil, Japan).
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.
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 product is marketed (maybe under another TM): US, Canada; in the EU marketed as EQUEST.
GENERIC BRANDS available? YES, but not too many.
Click here to learn more about GENERIC vs. ORIGINAL drugs.
QUEST oral gel for horses is a horse wormer with original moxidectin from ZOETIS.
Moxidectin is a macrocyclic lactone introduced in the market in the early 1990s (by AMERICAN CYANAMID → PFIZER → ZOETIS). It is moderately used in livestock and pets. It is effective against most species of roundworms that affect horses and against bots (Gasterophilus spp), but not against tapeworms.
Moxidectin and other 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 moxidectin administered at 400 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.
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.