Efficacy of a 1% lambdacyhalothrin cattle Pour-on (Saber) against sucking and biting lice infesting beef cattle

Four studies were conducted to determine the efficacy of a 1% lambdacyhalothrin pour-on (Saber Pour-on, Schering-Plough Animal Health) for control of sucking lice (Linognathus vituli, Haematopinus eurysternus, Solenopotes capillatus) and biting lice (Damalinia bovis) on beef cattle. Seventy-four mixed-breed cattle naturally infested with one or more species of lice at locations in Wisconsin, Nebraska, Oklahoma, and North Dakota were included in the study. Pretreatment lice samples were taken and identified by genus with the exception that sucking lice were not identified by genus at the North Dakota site. In January or February, half of the cattle at each location received a single application of 1% lambdacyhalothrin pour-on at 10 ml per head for cattle weighing less than 273 kg (600 lb) or 15 ml per head for cattle weighing 273 kg or more. The other cattle at each site served as untreated controls. Lice on designated body areas were counted 2, 4, 6, and 8 weeks after treatment, and the sum of all lice observed on each counting area was reported for each animal. The collective efficacy 6 weeks after treatment against three species of sucking lice (L. vituli, H. eurysternus, S. capillatus) was 88.4% at the Wisconsin site, 92.0% at the North Dakota site, and 100% at the Nebraska and Oklahoma sites. The 1% lambdacyhalothrin pour-on eliminated all biting lice within 2 weeks after treatment, and no biting lice were detected 8 weeks after treatment. A single treatment of 1% lambdacyhalothrin pour-on administered when lice populations were highest (January or February) provided effective season-long control of both biting and sucking lice on cattle.     

Therapeutic and persistent efficacy of spinosad applied as a pour-on or a topical spray against natural infestations of chewing and sucking lice on cattle

Studies were conducted in Wisconsin and Illinois, USA, to assess and compare the therapeutic and persistent efficacy of spinosad when applied as either a pour-on or topical spray and compared with cyfluthrin pour-on and coumaphos topical spray for controlling natural infestations of chewing (Bovicola bovis) and sucking (Linognathus vituli, Solenopotes capillatus and Haematopinus eurysternus) lice on cattle. Thirty-five animals at each trial site were blocked according to pre-treatment lice counts and randomly allocated to one of five treatment groups: single treatments of spinosad (25 g/L), diluted with water to 0.04% active ingredient and applied as a whole-body topical spray; spinosad (25 g/L) applied as a neat pour-on at 2 mg/kg body weight; Co-Ral Emulsifiable Livestock Insecticide (5.8% coumaphos), diluted to 0.03% active ingredient and applied as a whole-body topical spray; CyLence Pour-on Insecticide (1% cyfluthrin), applied as a neat pour-on at the manufacturer's recommended use rate for lice; and untreated control. Both spinosad treatments and cyfluthrin provided > or =96% control of B. bovis for up to 7 weeks, whereas the efficacy of coumaphos dropped to <90% after week 5 at one site. Spinosad spray had the best therapeutic and residual control of all treatments against L. vituli, > or =98% for at least 5 weeks at both sites, compared with 3 weeks for coumaphos at one site. Spinosad and coumaphos sprays provided 100% control of S. capillatus for at least 8 weeks compared with > or =97% control for spinosad and cyfluthrin pour-on treatments over the same interval. While H. eurysternus burden was low and limited to one study site, all four treatments provided 100% control for at least 6 weeks. These studies showed that topically applied spinosad provided a high degree of therapeutic and residual control against both sucking and chewing lice.     

Efficacy of a pour-on formulation of doramectin against lice, mites, and grubs of cattle

OBJECTIVE: To determine effectiveness of a pour-on formulation of doramectin against Damalinia bovis, Haematopinus eurysternus, Linognathus vituli, Solenopotes capillatus, Chorioptes bovis, Sarcoptes scabiei, Hypoderma bovis, and Hypoderma lineatum. ANIMALS: Cattle of various ages with naturally acquired or artificial infestations with 1 or more species of lice, mites, or grubs. PROCEDURE: In 10 louse and 6 mite studies, cattle were treated with doramectin (500 microg/kg, topically) on day 0, and parasite counts were performed approximately weekly from days 0 to 35. In 6 grub studies, cattle expected to harbor Hypoderma spp were treated before emergence of warbles. After warbles began to emerge, they were counted every 2 weeks, and grubs were collected and identified by species. RESULTS: Burdens of D bovis, H eurystemus, L vituli, and S capillatus on doramectin-treated cattle were 0 by 28 days after treatment. Burdens of C bovis and S scabiei decreased to 0 in naturally infested cattle and approximately 0 in artificially infested cattle by day 14 to 15. In grub studies, 107 of 136 control cattle had warbles, whereas 2 of 136 doramectin-treated cattle had 1 warble each, which represented a cure rate of 98.5%. CONCLUSION AND CLINICAL RELEVANCE: One topical application of doramectin was highly efficacious against common species of lice, mites, and grubs known to affect performance, health, and appearance of cattle.     

The persistent efficacy of doramectin pour-on against biting and sucking louse infestations of cattle

A repeated-exposure challenge model was used to evaluate the pour-on formulation of doramectin in preventing the establishment of louse infestations in cattle. Twenty calves cleared of preexisting biting and sucking louse infestations were randomly and equally allocated to either a doramectin-treated or untreated control group, with five replicates per group. Doramectin pour-on was administered topically at a dose rate of 500 microg/kg body weight. Every 14 days, from a pool of seeder calves with infestations of at least 50 biting and 50 sucking lice each, 10 calves were selected and 1 was placed in each replicate pen. Every week during the 112-day study, 9 predilection sites on the doramectin-treated and untreated calves were examined to estimate the louse population density. A calf met the infestation criterion for a louse species when two or more live lice were counted on two or more body regions for two consecutive count days. Because only 4 of 10 untreated calves acquired Solenopotes capillatus infestations, the persistent efficacy of doramectin against S. capillatus was not evaluated. Bovicola bovis and Linognathus vituli infestations in the untreated calves developed shortly after exposure to infested seeder calves. The acquisition of B. bovis and L. vituli infestations in the doramectin-treated group was delayed for 77 days and 105 days, respectively.     

Persistent activity of moxidectin pour-on and injectable against sucking and biting louse infestations of cattle

To evaluate the persistent activity of pour-on and injectable moxidectin against natural challenge by sucking (predominantly Linognathus vituli) and chewing (Bovicola bovis) cattle lice, 96 mixed-breed calves that had been treated to remove all lice were blocked by body weight and randomly allocated to three treatments: untreated control, moxidectin at 500 microg/kg by topical application and moxidectin at 200 microg/kg by subcutaneous injection. Twelve pens were blocked into groups of four and randomly allocated to four challenge times: 14, 21, 28 and 35 days post-treatment. Treatment groups were assigned to challenge pens randomly. Two donor calves, with demonstrated infestations of both sucking and chewing lice, were introduced into each pen containing eight principal calves at the start of each challenge time. Donors remained in the challenge pen for 7 days. Principal calves were examined for lice, 7, 14, 21 and 28 days after donor removal using a standardized hair-parting technique. Moxidectin injectable prevented re-infestation with L. vituli for up to 42 days, but did not provide persistent activity against B. bovis longer than 35 days post-treatment. Moxidectin pour-on demonstrated persistent activity against both B. bovis and L. vituli for 42 days.     

Efficacy of zeta-cypermethrin as pour-on or spray formulations for the control of buffalo fly (Haematobia irritans exigua) in cattle

Objective To determine the efficacy of zeta-cypermethrin in controlling buffalo fly ( Haematobia irritans exigua ).
Design Five field trials in northern and central Queensland.
Procedure Zeta-cypermethrin pour-on at 2.5 mg/kg, spray at 62.5 ppm, deltamethrin pour-on and pour-on vehicle were applied to groups of 20 cattle. Buffalo fly counts were conducted three times before treatment and 3, 7, 14, 21, 28 and 35 days after treatment.
Results In central Queensland where synthetic pyrethroid resistance in buffalo fly populations was rare, 2.5 mg/kg of zeta-cypermethrin pour-on gave good control of buffalo fly for 4 weeks and was better than a deltamethrin product. A zeta-cypermethrin spray used at 62.5 ppm gave 14 days control. In far-north Queensland where resistance to synthetic pyrethroids and heavy rain was common, the maximum period of efficacy of zeta-cypermethrin pour-on was reduced to 2 weeks.
Conclusion In areas where there is low resistance to synthetic pyrethroids among buffalo flies, zeta-cypermethrin pour-on can be expected to give good control for 4 weeks.     

Persistent efficacy of doramectin topical solution against induced infestations of Bovicola bovis and Solenopotes capillatus.

A study was conducted in two locations, Wyoming and Wisconsin, USA, to evaluate the persistent efficacy of doramectin topical solution at a dose rate of 500 microg/kg body weight against artificially induced infestations of Bovicola bovis and Solenopotes capillatus on cattle. At each location, lice-free beef calves were individually housed and randomly allocated to treatment. Both B. bovis and S. capillatus were transferred from untreated donor animals to doramectin-treated cattle at the end of 35, 63, 91 or 126 day post-treatment periods. Cattle treated with a saline pour-on served as the control. Based on the geometric means of lice counts 2 weeks following transfer, the persistent efficacy of a single treatment with doramectin topical solution against induced infestations of B. bovis was 100.0, 100.0, 99.5, and 100.0% at post-treatment days of 35, 63, 91, and 126, respectively. Persistent efficacy against induced infestations of S. capillatus, for the same intervals, were 100.0, 94.9, 86.3, and 74.9%.     

Persistent activity of moxidectin long-acting injectable formulations against natural and experimentally enhanced populations of lice infesting cattle

A study was conducted under a common protocol in Wisconsin and Wyoming, USA, to evaluate therapeutic and persistent efficacy of two long-acting injectable formulations of moxidectin against lice populations infesting cattle. At each site, 30 beef calves were blocked into groups of three based on naturally acquired Linognathus vituli populations, then randomly assigned to treatments within blocks. Treatments, injected subcutaneously into the proximal third of the ear on Day 0, included saline, a long-acting oil-based formulation containing 10% moxidectin given at the rate of 1 mg moxidectin/kg body weight (M10/1.0), or a long-acting oil-based formulation containing 15% moxidectin given at the rate of 0.75 mg moxidectin/kg b.w. (M15/0.75). Species of sucking and chewing lice were quantified on nine predilection sites before treatment, then 28, 63, 98, 133 and 168 days after treatment. During intervals between lice counts after Day 28, study animals from the three treatment groups were commingled for 32 days with two lice-free sentinels plus four to six seeder calves with infestations of both sucking and chewing lice. Following each 32-day commingling interval, seeder and sentinel animals were removed, and principal animals were sorted into pens by treatment. Lice were quantified on sentinel animals on the day of removal, and lice were quantified on principal study animals 3 days after removal of sentinel and seeders. Moxidectin was generally not efficacious against Bovicola bovis in the injectable formulations tested, whereas Haematopinus eurysternus infestations were inadequate to judge product effectiveness. Based on geometric means, both M15/0.75 and M10/1.0 provided statistically significant therapeutic efficacy against existing infestations of L. vituli and Solenopotes capillatus (100% efficacy on Day 28), and provided persistent protection against reinfestation with L. vituli and S. capillatus (efficacy >97%) for at least 133 days following treatment.     

Comparative efficacy of several insecticides for control of cattle lice (Mallophaga: Trichodectidae and Anoplura: Haematopinidae)

Several insecticides were applied to cattle at various rates, mixtures, application methods and numbers of treatments and evaluated for control of cattle lice. The insecticides included permethrin at various rates as a pour-on with and without the synergist piperonyl butoxide (PBO), and also at various rates as a spray with and without PBO. Pirimiphos-methyl was evaluated as a pour-on at various rates and with one or two applications. Lambda cyhalothrin in microencapsulated formulation was compared to a non-microencapsulated formulation. Rabon(R) was applied as a pour-on at two rates and at one or two treatments for each rate. Dimilin(R) was applied as a pour-on at two rates and mixed with permethrin and applied at two rates. Five endectocides, Eprinex(R), Ivomec(R), Dectomax(R), Cydectin(R) and Phoenectin(R) were all applied at the same rate. The cattle utilized in this research were all infested with a mixture of lice species. The species included: Bovicola (Damalinia) bovis (L.), Haematopinus eurysternus (Nitzsch), Linognthus vituli (L.) and Solenoptes capillatus (Enderlein). Most of the cattle were infested with at least two species and some had three or all four species present. All of the treatments except permethrin 1.0%+5% PBO, at a rate of 3ml/45.4kgwt. provided acceptable lice control with one application. Data indicated that applying the insecticides in early January should provide enough control to render the need for a second treatment unnecessary.     

Prevalence of sucking and chewing lice on cattle entering feedlots in southern Alberta

Beef calves from 2 sources entering southern Alberta feedlots in the winters of 1997-98 and 1998-99, were surveyed for the presence of lice. A random sample of multiple source (MS), that is, auction market-derived, calves entering commercial feedlots and single source (SS) calves entering a backgrounding feedlot were examined for the presence of lice at entry to the feedlot. A standardized examination, which involved hair-part examination of 8 louse predilection sites, was conducted on each selected calf to determine prevalence and intensity of infestation. The long-nosed sucking louse, Linognathus vituli, was the most commonly encountered species. This species infested from 57.8% to 95.6% of the calves selected from both MS and SS calves during both winters. Louse index values, indicating intensity of infestation, for L. vituli ranged from 1 to 243 lice per animal. The chewing louse, Bovicola bovis, was present on MS and SS calves only in the winter of 1998-99. The louse index values for B. bovis ranged from 1 to 230 lice per animal. Mixed infestations of the L. vituli and B. bovis were common. The little blue cattle louse, Solenopotes capillatus, was present only on the SS calves in the winter of 1997-98. The short-nosed sucking louse, Haematopinus eurysternus, was present at very low intensities, 1-2 lice per animal, on 2.6% to 4.4% of the MS calves during both winters. Comparison of results from the current study with published literature suggests that efforts to determine the economic impact of louse infestations are confounded by the lack of a uniform method to assess louse population levels.     

The efficacy of injectable and pour-on formulations of moxidectin against lice on cattle

SUMMARY The efficacy of one administration of moxidectin against natural infestations of the 3 common species of cattle lice in Australia: Linognathus vitull, Damallnla bovls and Haematoplnus eurysternus, was determined. A high degree of control of L vituli (too long-nosed sucking louse) was achieved with both the cattle Injection (96.7% and 100%) at 0.2 mg/kg and the cattle pour-on formulation (94.6% and 100%) at 0.5 mg/kg on the 2 farms where this louse occurred. An Injection of moxidectin at 0.2 mg/kg did not eliminate D bovis. In these trials efficacy ranged from nll to 85.2%. In contrast the pour-on formulation at 0.5 mg/kg provided consistently high efficacy (83.6 to 100%) against D bovis on 3 farms. Infestations of H eurysternus (the short-nosed sucking louse) were low and no significant difference was recorded between treatment groups In a single trial, however, lice persisted on 3 to 7 cattle In the untreated group at each Inspection, whereas none were found on any animals in the 2 groups treated with moxidectin on Inspection after treatment.     

EFFICIENCY AND SAFETY OF METHIDATHION APPLIED AS A POUR-ON SYSTEMIC INSECTICIDE FOR CONTROL OF CATTLE LICE

Methidathion applied to cattle as a pour-on insecticide for control of lice (predominantly Linognathus vituli, but also Haematopinus eurysternus and Damalinia bovis) caused a reduction in the lice population of approximately 98% to 99% in laboratory trials at the minimum recommended dose of 4 mg/kg and a 98.8% to 100% efficiency was achieved in field trials. In a comparative efficiency trial in the laboratory methidathion at 3.5 to 5 mg/kg reduced the lice population by 98.8% to 99%, fenthion by 98.5% at 4.5 mg/kg and famphur by 99.7% at 16.5 mg/kg. Methidathion was tolerated by calves aged 15 to 20 weeks at dose rates up to 40 mg/kg indicating an approximate 7 fold safety margin, but 1 of 4 calves treated at 50 mg/kg died following treatment. Treatment with fenthion at 50 mg/kg, 7.4 times the average recommended rate, famphur at 75 mg/kg, 3 times the average rate and chlorpyrifos at 85 mg/kg, 5 times average rate, caused reductions in whole blood cholinesterase activity of 52%, 27% and 47% respectively which were similar to the reductions in cholinesterase activity found in calves treated with methidathion at similar levels above the recommended commercial dose rates. It was found that 2 day old calves were more sensitive to treatment with methidathion than calves 9 or 16 days old. A further 11,900 cattle of varying age, breed and sex were treated with methidathion under field conditions at the recommended rate of 4 to 8 mg/kg, and 534 cattle were treated at 24 mg/kg without any signs of toxicity.     

Survey on blood-sucking lice (Phthiraptera: Anoplura) of ruminants and pigs with molecular detection of Anaplasma and Rickettsia spp

Lice may serve as biological or mechanical vectors for various infectious agents. To investigate louse infestation of ruminants and pigs, and pathogens potentially transmitted by them, anopluran lice (n=1182) were collected in Hungary, and evaluated for the presence of anaplasma, rickettsia and haemotropic mycoplasma DNA. On cattle the following species were found: Linognathus vituli (57%), Haematopinus eurysternus (38%) and Solenopotes capillatus (5%). L. vituli had a lower mean individual count/host when compared to H. eurysternus. On calves only L. vituli was observed, with a higher louse burden than on full-grown cattle. H. eurysternus and S. capillatus were more likely to occur simultaneously with another species on the same host, than L. vituli. Goats infested with Linognathus stenopsis had the overall highest prevalence (68%), while pigs harbouring Haematopinus suis showed the lowest (<1%). Anaplasma DNA was detected in 50% of pools analysed. In L. vituli Anaplasma ovis (or a closely related novel Anaplasma marginale genotype) was identified. Anaplasma-positivity of H. suis suggests that pigs may extend the reservoir and/or host spectrum of relevant species. Anaplasma-infected L. stenopsis pools show for the first time that caprine anaplasmosis is endemic in Hungary. Rickettsia spp. were demonstrated from Linognathus spp. and H. eurysternus. No haemotropic mycoplasmas were detected in any samples. In conclusion, this is the first molecularly confirmed report of bovine and ovine Anaplasma spp. in L. vituli, L. stenopsis and H. suis. The present results suggest that phthirapterosis of domestic animals deserves more attention, and lice should be evaluated among the broad range of potential vectors of arthropod-borne pathogens.     

Louse and mite infestation in domestic animals in northern Nigeria

Records of domestic animals brought to the Veterinary Entomology Laboratory for diagnosis of suspected lice and mite infestation over a 10 year period were analysed. From a total of 794 suspected cases, 137 (17.3%) and 247 (31.1%) were positive for lice and mange mites respectively. The most common lice species recorded were Linognathus vituli (66.7%) on cattle, L. ovillus (83.3%) on sheep, Haematopinus suis (100%) on pigs and Menacanthus stramineus (54.5%) on poultry. Other lice species recorded included Haematopinus bovis and Solenopotes capillatus on cattle, Damalinia ovis on sheep, Linognathus stenopsis and Menacanthus stramineus on goats, Goniocotes sp. on a horse, Linognathus setosus and Menacanthus stramineus on dogs, Goniodes gigas, Lipeurus caponis, Menopon gallinae and Chelopistes meleagrides on poultry. The most common mite species were Demodex folliculorum on cattle (96.9%) and on dogs (80.8%), Sarcoptes scabiei on pigs (100%) and Notoedres cati (80.3%) on rabbits. Other mite species included Psoroptes communis, Cheyletiella parasitivorax, Ornithonyssus gallinae and Dermanyssus gallinae.     

Efficacy of chlorfenapyr (AC 303630) experimental pour-on and CyLence formulations against naturally acquired louse infestations on cattle in New York

The four chlorfenapyr formulations examined provided 100% control of both the nymphal and adult stages of naturally acquired Bovicola bovis (L.) on cattle up to 35 days after application. Treatment with 6mg chlorfenapyr per kg BW in a 0.12ml per kg BW formulation was as effective as treatment with CyLence (cyfluthrin) in controlling naturally acquired Solenopotes capillatus (Enderlein) on cattle for 35 days. Percent reduction was never greater than 90% with any chlorfenapyr application against Linognathus vituli (L.). However, percent reduction was greater than 90% with CyLence from day 21 through 35. No adverse effects were noted on cattle from any of the chlorfenapyr dosages used.     

Arthropod parasites of Nubian ibexes (Capra ibex nubiana) and gazelles (Gazella gazella) in Israel.

In a 20-year survey the following ectoparasites were collected from Nubian ibexes: larvae of an unidentified Oestrus sp. collected from the nasal cavities, sinuses and horns, hippoboscid flies (Lipoptena chalcomelaena) specific to the Nubian ibex, blood sucking lice (Linognathus africanus) and unidentified biting lice (Damalinia sp.). Ibexes were severely infested with the cattle tick, Boophilus annulatus; a few Hyalomma anatolicum excavatum ticks were also collected. In five ibexes kept in two zoos, showing otitis, Psoroptes cuniculi, was identified, and from skin scrpaings of nine animals with severe dermatitis in three other zoos, Sarcoptes scabiei was isolated. Infestation of Nubian ibexes with sucking and biting lice as well as H. anatolicum excavatum is reported for the first time. The ectoparasites collected from gazelles were: hippoboscid flies (Lipoptena capreoli), calliphorid flies (Lucilia sericata and Calliphora sp.), sucking lice (Linognathus africanus and Solenopotes capillatus) and unidentified biting lice (Damalinia sp.), fleas (Ctenocephalides felis felis), and ticks, B. annulatus, Rhipicepahlus bursa, Rhipicephalus turanicus, H. anatolicum excavatum and H. marginatum rufipes. In skin scrapings of four gazelles with local dermatitis in the fetlocks Chorioptes bovis was identified. Neoschoengastia sp. was found in craters between the claws in three gazelles.     

Eradication of lice in cattle.

The purpose of this field study was to develop and evaluate eradication as a strategy to control lice in cattle. Thirty-three herds of cattle were selected and observed during a period of two and a half years. Before eradication, biting lice (Damalinia bovis) were present in 94% of the herds and 27% of the animals. Sucking lice (Linognathus vituli) were present in 42% of the herds and 5% of the animals. These levels were very similar to those reported from other countries in Northern Europe. The eradication strategy was successful in 28 of 33 herds, but lice were still present in 5 herds 3 to 6 months after treatment. Biting lice were present in all these 5 herds, sucking lice were present in 3 herds. During the next 12 months, nine of the 28 herds were reinfected with lice. Six herds were reinfected with just biting lice, 2 herds with just sucking lice and one herd was reinfected with both. There was no significant difference between the 2 louse species regarding the risk of unsuccessful eradication or reinfection. The only significant risk factor for reinfection was either purchase of livestock or use of common pasture, combined with failure in pre-treatment of newly introduced animals.     

Sustainability of Tsetse Control by Subsequent Treatment of 10% of a Previously Treated Ugandan Cattle Population with 1% w/v Deltamethrin

This study was conducted in Masaba and Masafu Sub-counties, Busia District, Uganda to assess the effect on the tsetse fly population of first treating all cattle with 1% w/v deltamethrin pour-on for a few months, followed by treating 10% of the cattle population. Treatment of all cattle for 6 months resulted in a significant reduction in the density of tsetse flies from 6.3 to 0.1 flies/trap/day (FTD), a 98.4% reduction. During the same period, the point prevalence of bovine trypanosomosis dropped from 37.7% to 2.9% (a 92.3% reduction). Treatment was resumed six months later, but this time only 10% of the cattle population received the pour-on treatment at three week intervals for a period of one year. This treatment maintained the tsetse fly density between 0 and 0.5 FTD and the prevalence of bovine trypanosomosis generally remained below 10%. In conclusion, under the local prevailing conditions, treatment of all communally grazed cattle with deltamethrin pour-on effectively suppressed the Glossina fuscipes fuscipes population. However, subsequent treatment of 10% of the cattle probably failed to control the tsetse fly population at a level sufficient to reduce trypanosomosis to acceptable levels.     

Treatment of natural infestations of the biting louse (Werneckiella equi) on horses using triflumuron, a benzoylurea derivative insect growth regulator

The horse biting louse (Werneckiella equi) is a common global equine ectoparasite. To our knowledge, benzoyl(phenyl)urea insecticides (triflumuron, diflubenzuron) commonly used as sheep lousicides, have not been evaluated for efficacy against W. equi. The aim of this study was to determine louse control efficacy, general wellness and dermal safety following triflumuron application as a backline pour-on to horses. Two efficacy trials using 25 adult naturally infested lousy horses, and a dermal safety trial using 10 adult louse-free horses were conducted over a 14-month period. Lousy animals were selected by assessment of their lice status prior to treatment. For the efficacy trial, the triflumuron product was applied at a dose of 2.5mg triflumuron per kg bodyweight (1 mL product per 10 kg bodyweight). For the safety study, triflumuron was applied at a 3x clinical dose of 7.5 mg triflumuron per kg bodyweight (3 mL product per 10 kg bodyweight). In our first efficacy trial, 100% lousicidal efficacy was achieved by day 44 post-treatment. In our second trial, no lice were identified on horses by day 71 post-treatment. In the safety trial, no adverse effects were seen. Results of this study demonstrate that the off-label, experimental pour-on application of triflumuron at 2.5 mg/kg bodyweight is convenient, highly effective and safe (at 3x the clinical dose) for the treatment of the horse biting louse, W. equi.     

THE INFLUENCE OF LIGHT INFESTATIONS OF LINOGNATHUS VITULI ON THE GROWTH OF YOUNG CATTLE

Groups of Hereford weaners carrying naturally acquired infestations of L. vituli were allocated to a factorial experiment to examine the effect of lice treatment, sex and nutrition on growth rate during winter and early spring. Plane of nutrition was the only factor influencing growth rate over this period. In untreated groups of cattle, the plane of nutrition influenced the lice score but lice score did not influence growth rate.