NZ754349B2 - Ectoparasitic Treatment Method and Composition - Google Patents

Abstract

The present invention relates to a method of controlling lice on an animal. The method comprises administering externally a pharmaceutically effective amount of thiacloprid. The present invention also relates to a composition comprising thiacloprid for use in controlling lice on an animal.

Description

ECTOPARASITIC TREATMENT METHOD AND COMPOSITION TECHNICAL FIELD This invention relates to an ectoparasitic treatment method and composition.

In particular, the present invention relates to the treatment of biting lice on sheep, although it should be appreciated that aspects of the present invention can be extended to related matters.

BACKGROUND ART Ectoparasites of animals are a significant concern, affecting the health of the animal, and the costs and productive output of farm animals. A particular problem for farmers in Australia is parasite infestation on sheep.

In Australia, lice and blowflies are the two most significant external parasite problems that affect sheep. Both parasite groups are the cause of extensive production losses and serious animal welfare concerns. Lice are ‘obligate parasites’, meaning that they only live on a host and can only survive for a relatively short time away from a host.

Lice are also said to be “species specific”, which means that generally, sheep lice only live on sheep. Accordingly, goats, cattle, pigs and horses are each affected by their own species of lice. Although sheep lice may survive on goats for a short period of time, goats are not likely to be carriers of sheep lice. Although sheep may commonly be affected by at least three species of lice, the most prevalent and most significant is the biting louse, Bovicola (formerly Damalinia) ovis.

In Australia, lice are estimated to cost the wool industry more than $120 million per year. These costs include expenditure on treatment and control of infestations as well as production losses. Significant reductions in fleece value (e.g. up to 30%), greasy fleece weight and clean fleece weight have all been demonstrated in lice-infested 17782756_1 (GHMatters) P93847.NZ.1 flocks (Wilkinson et al., 1982; Niven & Pritchard, 1985; Elliott et al., 1986; Cleland et al., 1989). Lice infestation has also been shown to detrimentally affect the colour of the fleece, i.e. making it less bright and more yellow (Kettle and Lukies, 1982), and can result in the downgrading of skins due to ‘cockle’ (Heath, 1995a).

The impacts on animal welfare and production due to sheep lice (e.g. B. ovis) are a consequence of the irritation experienced by infested sheep. Primarily, the sheep show signs of pruritus (itchiness) such as rubbing, biting and scratching and these behaviours damage the integrity of the fleece (e.g. causing ‘pulled’ or cotted wool). In some sheep the pruritus can be intense and the irritation can manifest as changes to the skin, including increased scurf and thickening of the epidermis and overlying lipid layer (Britt et al. 1986; Heath et al. 1995b). There is variation between individual sheep susceptibility to lice and this may be linked to an immune response to infestation (James 1999; James et al. 2002).

B. ovis are recognised as feeding on “skin scurf, lipids, loose stratum corneum squames and bacteria” (James, Moon & Brown, 1998). Although most lice (particularly adults) have been observed in the fleece, away from the skin surface, they are quite mobile and are likely to feed on substrates other than just the loose debris present at that location (Sinclair, Butler & Picton, 1989). The feeding behaviour of B. ovis at skin level appears to occur only on the surface of the epidermis and does not bring it into direct contact with the internal tissues or blood of the host. Observations have determined that B. ovis “does not ingest nucleated keratinocytes and apparently does not penetrate deeper than the outer layers of the stratum corneum” (James, Moon & Brown, 1998).

Lice are transmitted between sheep via direct contact. 17782756_1 (GHMatters) P93847.NZ.1 The control of lice requires effective chemical treatment of an entire flock and subsequent biosecurity measures to prevent re-infestation (i.e. exclusion of lice- infested sheep).

External administration of ectoparasiticides to sheep is usually most effective when applied immediately after shearing (off-shears). In particular, treatment by backlining either by pour-on or spray on is recommended to be applied within 24 hours of shearing, although within 7 days may be suitable for some products.

Treatment using ‘dipping’ administration methods can generally be used on longer wool than backlining. These methods include plunge dipping, shower dipping and cage dipping. Administration is recommended within 2 weeks of shearing, although up to 6 weeks after shearing may also be suitable. Treatment of sheep with long wool may require hand-jetting or a specialised long-wool backlining treatment.

Not all parasiticidal actives are suitable for all of these different types of administration, due to various reasons including mode of action, safety, formulation requirements, persistency and potency.

The administration of any chemical parasiticide will to some degree result in residue on the animal. If a smaller quantity of parasiticide can be used, the resultant residues may also be lower. For high volume applications such as dipping or jetting, residues in the environment may also be reduced by using lower concentrations of suitable actives. However, the actives must maintain efficacy at lower concentration to be suitable. The use of lower quantities of actives is also desirable to lower cost and/or potentially decrease safety issues. Lower residues are desired in that they may provide shorter withhold times, avoid export limitations, and increase market acceptability.

In Australia the common types of externally administered chemical parasiticides suitable for the treatment and/or prevention of sheep lice include insect growth 17782756_1 (GHMatters) P93847.NZ.1 regulators (IGRs), such as triflumuron; spinosyns, such as spinosad; macrocyclic lactones, such as ivermectin; magnesium fluorosilicate; organophosphates ; synthetic pyrethroids; and the neonicotinoid imidacloprid.

IGRs do not affect adult lice, resulting in a delay of up to 14 weeks for the developing stages to be killed and for the adult lice to die off. There have also been reports of emerging resistance to IGRs in Australia.

Spinosyns have low toxicity and provide rapid knock-down, but have a short duration of action.

Macrocyclic lactones also provide rapid knock-down, but are required to be administered in relatively large quantities to be effective.

Organophosphates are under increased scrutiny in regard to safety. In Australia the use of diazinon, the most commonly used organophosphate for control of sheep lice, has been discontinued since May 2007.

Synthetic pyrethroids can take 6-8 weeks to kill lice, which may lead to further spreading of lice across a flock. Significant resistance has also occurred with synthetic pyrethroids, being reported since the 1980s. The resistance has progressed to the extent that the use of synthetic pyrethroids in many locations may no longer be effective in the control of sheep lice.

In Australia, imidacloprid is the active ingredient in the parasiticide product Avenge™, sold by Bayer Australia Ltd, for the control of lice on sheep. Avenge™ contains imidacloprid at a concentration of 3.5% w/v, and is applied as a backline treatment.

When used for lice control on sheep, Avenge™ provides up to four weeks of persistent activity when applied within 24 hours following shearing, which can prevent reinfestation by lice. 17782756_1 (GHMatters) P93847.NZ.1 There is a clear need for alternative methods for controlling ectoparasites such as sheep lice. Ideally such methods would use an active with high potency against lice to allow for relatively low quantities and concentrations of actives during use, be suitable for both off-shears (short wool) and long wool treatments, and have high persistency.

It is an object of the present invention to address one or more of the foregoing problems and/or to at least provide the public with a useful choice.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicant reserves the right to challenge the accuracy and relevance of the cited documents.

It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in Australia or New Zealand or in any other country.

Throughout this specification, the word “comprise”, or variations thereof such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. 17782756_1 (GHMatters) P93847.NZ.1 DISCLOSURE OF THE INVENTION The invention is based in part on the surprising discovery that thiacloprid has high potency and suitability for the control of lice, when applied externally to an animal.

Thiacloprid is as shown in the chemical formula: Thiacloprid: [3-[(6-Chloropyridinyl)methyl]thiazolidinylidene]cyanamide is an insecticide of the neonicotinoid class.

The present invention provides the following items 1 to 28: 1. A method of controlling lice on an animal, characterised by the step of administering externally a pharmaceutically effective amount of thiacloprid. 2. The method of item 1, characterised by the step of topically administering a composition containing from 0.0001% to 3.5% w/v of thiacloprid. 3. The method of item 1 or 2, wherein the amount of thiacloprid administered to the animal is from 1 to 45 mg/kg by weight of the animal. 4. The method of item 3, wherein the amount of thiacloprid administered to the animal is from 10 to 30 mg/kg by weight of the animal.

. The method of any one of items 1 to 4, wherein the method includes the step of diluting a composition containing from 30% to 60% w/v of thiacloprid with water before administering the diluted composition to the animal. 6. The method of item 5, wherein the composition is diluted with water to provide from 1 ppm to 200 ppm of thiacloprid. 17782756_1 (GHMatters) P93847.NZ.1 7. A method of providing persistent control of lice on an animal, characterised by the step of administering externally a pharmaceutically effective amount of thiacloprid. 8. The method of item 7, wherein persistent control is provided for at least two weeks following administration. 9. The method of any one of items 1 to 8, wherein the thiacloprid is administered to the animal by backlining, dipping or jetting.

. Use of thiacloprid in the manufacture of a composition for controlling lice on an animal. 11. The use of item 10, wherein the composition contains from 0.0001% to 60% w/v of thiacloprid. 12. The use of item 11, wherein the composition contains from 0.0001% to 3.5% w/v of thiacloprid. 13. The use of item 11, wherein the composition contains from 30% to 60% w/v of thiacloprid. 14. The use of any one of items 10 to 13, wherein the amount of thiacloprid administered to the animal is from 1 to 45 mg/kg by weight of the animal.

. The use of item 14, wherein the amount of thiacloprid administered to the animal is from 10 to 30 mg/kg by weight of the animal. 16. The use of any one of items 10 to 15, wherein the composition is administered to the animal by backlining, dipping or jetting. 17. Use of thiacloprid in the manufacture of a composition for persistent control of lice on an animal. 18. The use of item 17, wherein the persistent control is provided for at least two weeks following administration. 17782756_1 (GHMatters) P93847.NZ.1 19. A composition comprising thiacloprid for use in controlling lice on an animal.

. The composition of item 19, wherein the composition contains from 0.0001% to 60% w/v of thiacloprid. 21. The composition of item 20, wherein the composition contains from 0.0001% to 3.5% w/v of thiacloprid. 22. The composition of item 20, wherein the composition contains from 30% to 60% w/v of thiacloprid. 23. The composition of any one of items 19 to 22, wherein the amount of thiacloprid administered to the animal is from 1 to 45 mg/kg by weight of the animal. 24. The composition of item 23, wherein the amount of thiacloprid administered to the animal is from 10 to 30 mg/kg by weight of the animal.

. The composition of any one of items 19 to 24, wherein the composition is administered to the animal by backlining, dipping or jetting. 26. A composition comprising thiacloprid for use in persistent control of lice on an animal. 27. The composition of item 26, wherein the persistent control is provided for at least two weeks following administration. 28. The method of any one of items 1 to 9, the use of any one of items 10 to 18, or the composition of any one of items 19 to 27, wherein the animal is a sheep or a goat. 17782756_1 (GHMatters) P93847.NZ.1 The present invention as claimed herein is described in the following items 1 to 8: 1. A method of controlling lice on an animal, characterised by the step of topically administering a pharmaceutically effective amount of thiacloprid, wherein the amount of thiacloprid administered to the animal is from 10 to 30 mg/kg by weight of the animal, wherein the thiacloprid is administered in a composition containing 0.5%-2% w/v of thiacloprid, and wherein the animal is a sheep or a goat. 2. The method of item 1, wherein the composition is administered to the animal by backlining. 3. The method of item 1 or 2, wherein the composition contains 1% w/v of thiacloprid. 4. The method of any one of items 1 to 3, wherein the amount of thiacloprid administered to the animal is from 10 to 15 mg/kg by weight of the animal.

. The method of any one of items 1 to 4, wherein the method provides persistent control of lice on the animal. 6. The method of item 5, wherein persistent control is provided for at least two weeks following administration. 7. The method of any one of items 1 to 6, wherein the animal is a sheep. 8. The method of item 1 substantially as herein described with reference to any one of the Examples.

MODES FOR CARRYING OUT THE INVENTION Throughout the specification, the use of the present invention will be particularly described in relation to the control of biting lice on sheep (Bovicola ovis). However, it should be appreciated that the principles in the present invention could apply to and be useful in other situations – for instance controlling biting lice (Bovicola caprae) on 17782756_1 (GHMatters) P93847.NZ.1 goats. Many of the problems associated with sheep are also present in goats having regard to their long hair and related physiological systems.

According to an aspect of the present invention there is provided a method of controlling lice on an animal, characterised by the step of administering externally a pharmaceutically effective amount of thiacloprid.

According to a further aspect of the invention there is provided a method of controlling lice on an animal, characterised by the step of topically administering a composition containing from 0.0001% to 3.5% w/v of thiacloprid.

According to a preferred aspect of the invention the amount of thiacloprid administered to the animal is from 1 to 45 mg/kg by weight of the treated animal.

More preferably the amount of thiacloprid administered to the animal is from 5 to 40 mg/kg by weight of the treated animal. Even more preferably the amount of thiacloprid administered to the animal is from 10 to 30 mg/kg by weight of the treated animal.

According to a preferred aspect of the invention the composition administered in the method of controlling lice on an animal contains from 0.1% to less than 3.5% w/v of thiacloprid. More preferably, the composition administered in the method of controlling lice on an animal contains from 0.5% to 2% w/v of thiacloprid. Preferably the composition is administered as a backline treatment. More preferably the composition is administered to a sheep within 7 days after shearing.

According to another preferred aspect of the invention the composition administered in the method of controlling lice on an animal contains from 1 mg/L (ppm) to 200 mg/L (ppm) of thiacloprid. More preferably, the composition administered in the method of controlling lice on an animal contains from 5 mg/L (ppm) to 100 mg/L (ppm) of thiacloprid. Even more preferably, the composition administered in the method of 17782756_1 (GHMatters) P93847.NZ.1 controlling lice on an animal contains from approximately 48 mg/L (ppm) of thiacloprid.

Preferably the composition is administered as a dip treatment. More preferably the composition is administered to a sheep within 6 weeks after shearing.

Preferably the method includes the steps of diluting a composition containing from % to 60% w/v of thiacloprid with water before administering to the animal. More preferably the composition is diluted with water to provide from 1 ppm to 200 ppm of thiacloprid.

According to another preferred aspect of the invention the composition administered in the method of controlling lice on an animal contains from 100 mg/L (ppm) to 1000 mg/L (ppm) of thiacloprid. More preferably, the composition administered in the method of controlling lice on an animal contains from 200 mg/L (ppm) to 600 mg/L (ppm) of thiacloprid. Preferably the composition is administered as a jetting treatment.

Preferably the composition is administered to a sheep after 2 weeks or more after shearing. More preferably the composition is administered to a sheep after 4 weeks or more after shearing.

According to another aspect of the present invention there is provided a method of providing persistent control of lice on an animal, the method including the step of administering topically a composition including thiacloprid. Preferably the method provides persistent protection for at least two weeks following administration.

According to another aspect of the present invention there is provided a composition for controlling lice on an animal, characterised by including thiacloprid. Preferably the composition includes from 0.0001% to 60% w/v thiacloprid. 17782756_1 (GHMatters) P93847.NZ.1 According to another aspect of the present invention there is provided a composition for use in a method of controlling lice on an animal, the composition including 30% to 60% w/v of thiacloprid. A particularly preferred composition includes in the order of 48% w/v thiacloprid.

According to another aspect of the present invention there is provided a composition for use in a method of controlling lice on an animal, the composition including 0.3% to less than 3.5% w/v of thiacloprid. More preferably, the composition administered in the method of controlling lice on an animal contains from 0.5% to 2% w/v of thiacloprid. A particularly preferred composition includes in the order of 1% w/v thiacloprid.

According to another aspect of the present invention there is provided a composition for use in a method of controlling lice on an animal, the composition including 1 mg/L (ppm) to 200 mg/L (ppm) of thiacloprid. More preferably, the composition administered in the method of controlling lice on an animal includes from 5 mg/L to 100 mg/L of thiacloprid. A particularly preferred composition includes in the order of 48 mg/L of thiacloprid.

According to another aspect of the present invention there is provided a composition for use in a method of controlling lice on an animal, the composition including 100 mg/L (ppm) to 1000 mg/L (ppm) of thiacloprid. More preferably, the composition administered in the method of controlling lice on an animal includes from 200 mg/L to 600 mg/L of thiacloprid. A particularly preferred composition includes in the order of 400 mg/L of thiacloprid.

The medicament can be administered to the animal (e.g. a sheep) by any suitable means, including but not limited to backlining, dipping, or jetting. In some embodiments, the composition is applied to all or a majority of the fleece or hair of the 17782756_1 (GHMatters) P93847.NZ.1 animal. In some embodiments, the composition is applied by localised topical application to part of the fleece or hair of the animal, e.g. to the back of the animal.

It should be appreciated that the present invention can be combined with other active ingredients, for instance as combined formulations or combination treatments. Other suitable actives include but are not limited to other parasiticides, anthelmintics, vaccines, vitamins/mineral supplements and the like. Not only does this offer advantages by having two or more treatments being delivered in a single dose, but they may also be synergistic effects resulting. For example, the inclusion of vitamins and minerals may assist the skin recovery of an animal once the biting lice have disappeared as a result of the insecticide treatment.

In preferred formulations, in addition to the active, there may be provided dispersing agents, wetting agents, surfactants, emulsifiers, solvents, co-solvents, thickeners, anti- oxidants, stabilisers, preservatives, anti-foaming agents, colourants and humectants.

Preferred methods of administration are discussed below. These methods are described with particular reference to administration to sheep, since sheep are the most typical species that is treated, however one skilled in the art will be aware of suitable adaptations and means for administering to other animals.

Dipping A traditional form of dipping for sheep is known as plunge dipping, wherein the sheep are mustered through a deep trough containing the treatment liquid. The sheep swim through the liquid allowing the liquid to penetrate into the fleece. The sheep may also be completely submerged into the liquid by a handler immersing each sheep’s head into the liquid.

An alternative method of dipping is known as shower dipping, wherein the sheep are sprayed with the treatment liquid from overhead nozzles and optionally from side 17782756_1 (GHMatters) P93847.NZ.1 spraying nozzles. A typical arrangement uses a circular treatment enclosure with a rotating boom arm with downwards spraying nozzles mounted above the enclosure.

The treatment time is approximately 12 minutes for the sheep to be sufficiently wetted with the treatment liquid.

Jetting The jetting procedure involves the use of a high pressure stream or jet of treatment fluid being directed onto the animal. The application technique includes manual hand- jetting and the use of an automated jetting race. Manual hand-jetting uses a pump to supply treatment fluid to a jetting-wand held by an operator, who administers the treatment to the sheep. The jetting-wand includes a spray head with a nozzle or nozzles for directing the liquid into the fleece of the sheep, which helps saturate areas of the fleece and provide skin contact with the fluid. The operator uses the jetting wand to apply the liquid as onto different areas of the animal’s body. The areas for administration may be chosen by the operator depending on the circumstances, such as wool length, and the requirements for different animals such as rams and wethers.

The pressure of the jets is typically around 700 kPa, and the minimum volume of treatment liquid is around 0.5 L per month of wool growth.

An automated jetting race is a less laborious method of jetting compared to hand- jetting, using apparatus that applies treatment liquid to the back of an animal as it passes under a series of nozzles while traveling through the apparatus. Generally a higher volume and lower pressure of treatment liquid is used, compared to hand jetting.

Backlining The backlining technique, otherwise referred to as pour-on or spray-on, is the application of a relatively small amount of liquid to back of an animal. The liquid may be applied as a spray or a stream or jet of liquid, using manual applicators or power assisted applicators. The volume, concentration viscosity and other properties of the 17782756_1 (GHMatters) P93847.NZ.1 treatment liquid may vary depending on the requirements. Typically a pour-on is administered in two or more bands along either side of the spine of the sheep.

The inventors have surprisingly discovered that thiacloprid has unexpectedly high efficacy in the control of lice on sheep.

One particular advantage provided by the present invention is the long persistency following administration. For instance, when thiacloprid is administered as a plunge- dip and/or pour-on, four weeks of persistency has been measured.

There is limited understanding in the prior art of the usefulness of thiacloprid in controlling parasites on animals.

The superior potency of thiacloprid compared to imidacloprid in the control of lice on sheep is a surprising result. The dose of imidacloprid recommended for the product AVENGE™ for the control of lice on sheep is around 49 mg/kg of the body weight of the sheep. By comparison, thiacloprid has been demonstrated as effective when used as a pour-on treatment at a dose as low as 5 mg/kg thiacloprid.

In one embodiment, the present invention provides a method of controlling lice on sheep, characterised by the step of administering externally thiacloprid in an amount of from 5 to 40 mg/kg by weight of the treated animal, wherein the thiacloprid is administered by localised topical application to the back of the animal. In one embodiment, the thiacloprid is administered as a pour-on. In one embodiment, the thiacloprid is administered as one or more bands along either side of the spine of the animal.

In one embodiment of the invention, the high potency of thiacloprid is utilised by the provision of a 1% w/v composition of thiacloprid for use as a backline treatment for 17782756_1 (GHMatters) P93847.NZ.1 lice control on sheep. By comparison, the backline imidacloprid formulation Avenge™, uses the substantially higher concentration of 3.5% w/v.

This significantly higher potency allows for lower concentrations and/or quantities of thiacloprid to be used compared to similar parasiticides such as imidacloprid. It can be seen that the present invention has a number of advantages over the prior art, including lower residues both on the animal and the environment, lower costs for manufacture, ease of manufacture, and a lower chance of lice developing resistance.

EXAMPLES In table 1 is a formulation example of the present invention. In particular this formulation may be used as a concentrate that is diluted with water for use in dipping, such as plunge dipping, cage dipping or spray dipping. Typically this formulation would be diluted to around 48 ppm for use in dipping.

Table 1: Formulation of thiacloprid concentrate Formulation 1 Ingredients Proportion Thiacloprid 48% Active Polysorbate 80 10-15% Surfactant Plasdone K25 2.0-5.0% Dispersing Xanthan gum 0.1- 0.3% Thickening Wacker silica 0.5- 1.5 Thickening/ dispersing Methyl paraben 0.2 Preservative Propyl paraben 0.04 Preservative Defoamer RD 0-0.1 Anti foam Propylene glycol 10- 20% Anti-freeze Deionised water Qs to 100% 17782756_1 (GHMatters) P93847.NZ.1 In table 2 is an example composition of the invention with particular suitability for use in a backlining treatment, such as a pour-on.

Table 2: Formulation of thiacloprid pour-on Formulation 2 Ingredients Proportion Thiacloprid 1.0% Active DMA (Dimethyl acetamide) 40% Solvent BHT 0.2% Antioxidant Dipropylene glycol methyl ether Qs to 100% Co-solvent Trial Example 1 Six sheep with a natural infestation of B. ovis were treated by hand jet with a 400 mg/L (ppm) solution of thiacloprid (approx. 4L per sheep). At 166 days after treatment average numbers of live lice on these sheep were reduced by 96.4%.

Trial Example 2 Six sheep infested with B. ovis were treated with 400 mg/L (ppm) thiacloprid by hand jet (approx. 5L per sheep). Lousicidal efficacy (calculated using geometric means and the Henderson-Tilton formula) was 99.5% at 104 days after treatment.

Trial Example 3 Subsequent studies were conducted in which various concentrations of thiacloprid were assessed for lousicidal efficacy when applied by hand jet to naturally-infested sheep.

Seven (7) different concentrations ranging from 300 ppm down to 20 ppm were assessed in these studies. A positive correlation between thiacloprid concentration and efficacy was observed. 17782756_1 (GHMatters) P93847.NZ.1 Trial Example 4 In this study, sheep with a natural infestation of lice were treated with aqueous solutions of thiacloprid ranging from 500 to 125 ppm, applied as a plunge dip. All sheep treated at all dose levels were found to be free from live lice at 20 weeks after treatment (WAT).

Trial Example 5 A subsequent study was performed in which lice-infested sheep were treated by plunge dip with various concentrations of thiacloprid from 120 to 15 ppm. Lousicidal efficacy was high at all concentrations.

Trial Example 6 A second dose-titration plunge dip study was conducted using six thiacloprid concentrations of around 15, 8, 4, 2, 1 and 0.5 ppm. Acceptable levels of efficacy were demonstrated at the three highest concentrations tested in this trial.

Trial Example 7 The efficacy of a concentration of 48 ppm was further confirmed when treatment of six lice-infested sheep successfully eliminated live lice from detection, when the sheep were assessed over a period of 12 months.

Trial Example 8 An in vitro assessment to compare the relative potencies of imidacloprid and thiacloprid was conducted by means of an adult louse bioassay. The results of this study indicated that thiacloprid was almost six times more potent than imidacloprid against a field strain of B. ovis when compared at the lethal concentration 50% (LC50) level. 17782756_1 (GHMatters) P93847.NZ.1 Trial Example 9 Another unexpected finding following plunge dip treatment with thiacloprid at 48 ppm was the persistence of lousicidal efficacy. In two studies, introduction of lice to treated sheep up to 4 weeks after treatment did not result in successful establishment of new infestations. This presents a significant advantage over other plunge dip products currently available for use on sheep in Australia for which such persistent lousicidal efficacy is not known to occur.

Trial Example 10 A study was performed using 10 g/L thiacloprid pour-on formulation, on four groups of sheep at different dose rates including a negative control group, as summarised in table 3. The results of the study demonstrated that thiacloprid 10 g/L pour-on effectively controlled a natural infestation of sheep lice when applied at a dose level as low as 0.5 mL per kg bodyweight (approximately 200 mg thiacloprid per square metre of sheep body surface area). At each assessment time, including 22 weeks after treatment, there was an absence of live lice on all three groups.

Table 3: Trial of 1% w/v thiacloprid pour-on Volume Nominal Number of Assessment Group Treatment administered Dose level Sheep times Thiacloprid 1 1.5 ml/kg 600 mg/m 8 g/L Pour-On Thiacloprid Pre-shearing, 2 1.0 ml/kg 400 mg/m 7 g/L Pour-On 4, 8, 12 and Thiacloprid 22 weeks post 3 0.5 ml/kg 200 mg/m 8 g/L Pour-On treatment Negative 4 Nil Nil 7 controls Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims. 17782756_1 (GHMatters) P93847.NZ.1 REFERENCES Wilkinson, F.C., de Chaneet, G.C. and Beetson, B.R. (1982). Growth of populations of lice, Damalinia ovis, on sheep and their effects on production and processing performance of wool. Veterinary Parasitology 9, 243-252 (Wilkinson et al, 1982).

Niven, D.R. and Pritchard, D.A. (1985). Effects of control of the sheep body louse (Damalinia ovis) on wool production and quality. Australian Journal of Experimental Agriculture 25, 27-31 (Niven and Pritchard, 1985).

Elliott, J., Jones, A.L. and Pauley, J.R. (1986). The effect of body lice on wool production. Australian Advances in Veterinary Science. Australian Veterinary Association, pp 125-126 (Elliott eat al., 1986).

Cleland, P.C., Dobson, K.J. and Meade, R.J. (1989). Rate of spread of sheep lice and their effects on wool quality. Australian Veterinary Journal 66, 298-299 (Cleland et al., 1989).

Kettle, P.R. and Lukies, J.M. (1982b). Effects of sheep lice Damalinia ovis on wool colour. New Zealand Journal of Experimental Agriculture 10, 15-17 (Kettle and Lukies, 1982).

Heath, A.C.G., Cooper, S.M., Cole, D.J.W. and Bishop, D.M. (1995). Evidence for the role of the sheep biting louse Bovicola ovis in producing cockle, a sheep pelt defect.

Veterinary Parasitology 59, 53-58 (Heath, 1995a).

Britt, A.G., Cotton, C.L., Pitman, I.H. and Sinclair, A.N. (1986). Effects of the sheep- chewing louse (Damalinia ovis) on the epidermis of the Australian Merino. Australian Journal of Biological Science 39, 137-143 (Britt et al, 1986). 17782756_1 (GHMatters) P93847.NZ.1 Heath, A. C. G., Cole, D. J. W., Bishop, D. M., Pfeffer, A., Cooper, S. M., Risdon, P. (1995). Preliminary investigations into the aetiology and treatment of cockle, a sheep pelt defect. Veterinary Parasitology 56, 239-254 (Heath, 1995b).

James, P.J. (1999). Do sheep regulate the size of their mallophagan louse populations? International Journal for Parasitology 29, 869-875 (James 1999).

James, P.J., Carmichael, I.H., Pfeffer, A., Martin, R.R. and O’Callaghan, M.G. (2002a).

Variation among Merino sheep in susceptibility to lice (Bovicola ovis) and association with susceptibility to trichostrongylid gastrointestinal parasites. Veterinary Parasitology 103, 355-365 (James et al., 2002).

James, P.J., Moon,R.D. and Brown, D.R. (1998). Seasonal dynamics and variations among sheep in densities of the sheep biting louse, Bovicola ovis. International Journal for Parasitology 28, 283-292 (James, Moon & Brown, 1998).

Sinclair, A.N., Butler, R.W. and Picton, J. (1989). Feeding of the chewing louse Damalinia ovis (Shrank) (Phthiraptera:Trichodectidae) on sheep. Veterinary Parasitology 30, 233-251 (Sinclair, Butler & Picton, 1989). 17782756_1 (GHMatters) P93847.NZ.1

Claims (8)

CLAIMS :

1. A method of controlling lice on an animal, characterised by the step of topically administering a pharmaceutically effective amount of thiacloprid, wherein the amount of thiacloprid administered to the animal is from 10 to 30 mg/kg by 5 weight of the animal, wherein the thiacloprid is administered in a composition containing 0.5%-2% w/v of thiacloprid, and wherein the animal is a sheep or a goat.

2. The method of claim 1, wherein the composition is administered to the animal by backlining. 10

3. The method of claim 1 or 2, wherein the composition contains 1% w/v of thiacloprid.

4. The method of any one of claims 1 to 3, wherein the amount of thiacloprid administered to the animal is from 10 to 15 mg/kg by weight of the animal.

5. The method of any one of claims 1 to 4, wherein the method provides persistent 15 control of lice on the animal.

6. The method of claim 5, wherein persistent control is provided for at least two weeks following administration.

7. The method of any one of claims 1 to 6, wherein the animal is a sheep.

8. The method of claim 1 substantially as herein described with reference to any 20 one of the Examples. 17782756_1 (GHMatters) P93847.NZ.1