Brand: CYREX ™ LIQUID

Company: ELANCO


FORMULATION: concentrate for topical administration to sheep by «dipping», «spraying» or «jetting»

ACTIVE INGREDIENT(S):

CHEMICAL CLASS of the active ingredient(s):


INDICATIONS: SHEEP


PARASITES CONTROLLED * (spectrum of activity)

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

  • For prevention and treatment of blowfly strike (incl. Lucilia cuprina) in all breeds of sheep for up to 12 weeks.
  • For the control of lice on coarse wool breeds of sheep
  • For the treatmet of lice on long-wool Merino sheep.

RECOMMENDED DOSE*

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

  • JETTING
    • Mix 2 L of product with 1000 L water (equivalent to 1000 ppm=mg/L cyromazine and 25 ppm=mg/L spinosad). 
    • Ensure saturation to skin level. Top up at the same rate. Apply a min, of 2 L of dipwash per sheep and an additional 0.5 L for each month of wool growth up to a max. of 5 L per sheep.
  • CR SHOWER
    • Mix 2 L of product with 1000 L water (equivalent to 1000 ppm=mg/L cyromazine and 25 ppm=mg/L spinosad). 
    • Ensure saturation to skin level. Top up at the same rate. No reinforcement is requires with the use of a Constant Replenishment (CR) shower dip. Do not allow the sump to fall below ¾ of total volume.
  • FLYSTRIKE DRESSING
    • Mix 10 mL of product with 5 L water (equivalent to 1000 ppm=mg/L cyromazine and 25 ppm=mg/L spinosad).
    • Apply into the affected area for the spot treatment of flystrike. Remove the wool from around the area to be treated using clippers or shears. Prepare a fresh dilution of dressing each day.

Read the product label for further details on dosing and administration.


SAFETY

  • LD50 (acute oral) in rats:
    • cyromazine: 3387 mg/kg for the a.i.
    • spinosad: >3600 mg/kg for the a.i.
  • Estimated hazard class according to the WHO classification of pesticides for cyromazine: U, unlikely to present acute hazard

Suspected poisoning? Read the articles on cyromazine safety and spinosad safety this site.

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

  • Meat: New Zealand: 7 days
  • Milk for human consumption: New Zealand: Milk intended for sale for human consumption must be discarded during treatment and for not less than 35 days following the last treatment.
  • Wool: New Zealand: 2 months.

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? LOW

Cyromazine is a particular case regarding resistance development. Blowflies developed resistance to most chemical classes and active ingredients that were successively used for their control in Australia (and to a large extent in New Zealand too):

  • Organochlorines (e.g. DDT, dieldrin): introduced in 1946 in Australia, field resistance detected in 1957. Withdrawn for safety reasons in the 1970s.
  • Organophosphates (e.g. diazinon, malathion): introduced in 1957 in Australia, field resistance detected in 1965. Withdrawn for safety reasons in Australia in the mid 2000s.
  • Benzoylphenyl ureas (e.g. diflubenzuron): introduced in 1993 in Australia, field resistance detected in 2001. Claim for blowfly strike prevention removed in Australia in 2008. Since then approved only for lice control.

First cases of blowfly field resistance to the mentioned chemical classes appeared usually about 10 years after product introduction. Other chemical classes such as synthetic pyrethroids (e.g. cypermethrin) and macrocyclic lactones (e.g. ivermectin) have been used only marginally for blowfly strike prevention during these years, i.e. it can be assumed that the selection pressure on blowflies exerted by chemicals of these two classes has been rather low.

It is now >35 years since the introduction of the first cyromazine product (VETRAZIN Liquid for dipping and jetting) in the late 1970s, and so far only one case of light tolerance in the field (Nimmitabel) has been reported in 2011 for Lucilia cuprina in Australia. However, even in the affected properties the product still accomplished its label claims. Tolerant flies exhibited a Resistance Factor (RF) of about 3, meaning that a three-fold concentration of cyromazine was required to kill the tolerant maggots when compared with the susceptible ones. RFs for organochlorines, organophosphates and/or benzoylphenyl ureas can reach more than 100, which means that more than a hundred-fold concentration of these compounds is required to kill resistant flies when compared with susceptible flies.

The reasons for this unexpected behavior of cyromazine regarding resistance are not completely elucidated. It may be related to the fact that the organochlorines, organophosphates and benzoylphenyl ureas were mostly used twice a year (once against blowfly strike prevention, once against lice), whereas cyromazine is usually used only once a year, which results in a lower selection pressure. It has also been also proposed that the gene mutations that confer resistance to cyromazine are not completely dominant, and that the cyromazine-tolerant flies have little biological advantage over the susceptible ones. These factors together make it difficult for the cyromazine-tolerant flies to multiply and become predominant in the fly population.

To our knowledge no reports on resistance or tolerance of blowflies (Lucilia cuprina, Lucilia sericata) to cyromazine have been reported in New Zealand, UK (and other EU-countries) or South Africa, regions where cyromazine has been also vastly used against blowfly strike for decades.

Spinosad, a natural insecticide belonging to the class of the spinosyns was introduced for use against body lice and blowfly strike in Australia in the early 2000s. So far there are no reports on resistance or tolerance of sheep body lice and blowflies to spinosad in Australia or New Zealand. However, other pests have already developed resistance to spinosad (e.g. houseflies) in several countries. And in the past, both body lice and blowflies have developed resistance to several classes of insecticides (e.g. organophosphates, synthetic pyrethroids, benzoylphenyl ureas) in Australia and New Zealand. Consequently it must be assumed that they may sooner or later develop resistance to spinosad as well, particularly if it is uninterruptedly used during years. To delay resistance development Integrated Pest Management (IPM) practices are a must, including product rotation with active ingredients showing mechanisms of action different from that of spinosad.

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it is likely to be due to incorrect use and not to resistance. Incorrect use is the most frequent cause of product failure.

Alternative chemical classes/active ingredients to prevent resistance of blowflies through product rotation:

These alternative products may not be available in all countries, or may not be available for dipping, jetting or dressing.

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 brand/product is marketed: New Zealand
GENERIC BRANDS available? Rather few ones so far with such a particluar composition.

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

Click here for an overview on the most used antiparasitic BRANDS witoncentrates for dipping, spraying, or jetting.


COMMENTS

CYREX LIQUID for sheep from ELANCO is a so far unusual combination of active ingredients with different modes of action: cyromazine (a specific flystrike preventative, ineffective against lice) and spinosad (effective against flystrike and lice).

Cyromazine is a so-called Insect Growth Regulators (IGR) belonging to the group of the Chitin Synthesis Inhibitors (CSI). It was introduced in the late 1970s (by CIBA-GEIGY → NOVARTIS → ELANCO). It is narrow-spectrum larvicide. It is abundantly used in sheep, moderately in poultry, marginally in horses, but not in other livestock or pets. It is also moderately used in agricultural pesticides.

Chitin is a component of the cuticle of insects, which is an essential part of their outer skeleton. If chitin is not properly produced, larvae die when they attempt the next molt. However, cyromazine does not really inhibit chitin synthesis, but interferes with its correct deposition. The consequence is the same: Fly maggots cannot complete molting and die. Other CSIs such as the benzoylphenyl ureas (BPUs, e.g. diflubenzuron, triflumuron) do actually inhibit chitin synthesis. But whereas BPUs exert this effect an almost all insects, cyromazine is quite specific for Dipterans (flies, mosquitoes, etc.) and some beetles. This makes it much less harmful for the environment, but also ineffective against other sheep pests such as lice.

As all IGRs, cyromazine has no knockdown effect. This means that flowfly maggots will die only at their next attempt to molt to the next developmental stage, which may take several days to occur, depending on age of the maggots at the time of treatment, humidity, temperature, etc. For this reason, IGRs are usually not used for curing established infestations, but for preventing their development by killing the larvae, and thus preventing the development of parasite populations in the fleece.

Cyromazine is quite soluble in water, in contrast with many other parasiticides that are rather lipophilic. This means that heavy rains may significantly shorten the length of protection of this and other cyromazine-based products.

Spinosad is a natural insecticide obtained from soil bacteria introduced for veterinary use by ELANCO in the 1990s. It is effective against numerous insects pests (e.g. lice, fleas and flies, etc.) and also against ticks and mites. In contrast with cyromazine, spinosad does have adulticidal effect, i.e. it will kill adult parasites as well as their immature stages within a few hours after treatment. This means that it can be also used as a curative agent. It is still scarcely used in livestock so far. It is also used against fleas on dogs and cats, and against poultry mites. It is moderately used in agriculture as well as against household pests. One of its major benefits is its rapid degradation in the environment and the low residues it leaves in animal tissues. Its major weakness for use on livestock is the rather short residual effect after topical administration (against flystrike: 4-6 weeks in Australia, 2-4 weeks in New Zealand).


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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