World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.): Third edition of the guideline for evaluating efficacy of anthelmintics in ruminants (bovine, ovine, caprine).

This guideline is aimed at those who are involved in the assessment of anthelmintic efficacy in ruminant livestock species (bovine, ovine and caprine). The intent is to provide a framework that can be adopted worldwide for the testing of anthelmintics in ruminants, such that studies carried out in different countries can be compared and thereby unnecessary duplication can be reduced. Recommendations are made for the selection, housing and feeding of study animals, the type of studies required, the method used to conduct those studies, the assessment of results and the standards for defining anthelmintic efficacy.

X-ray Fourier transform holography with beam shaping optical elements.

Holography is a powerful method for achieving 3D images of objects. Extending this method to short wavelengths potentially offers significantly higher resolution than visible light holography. However, current X-ray holography setups employ nanoscale pinholes to form the reference wave. This approach is relatively inefficient and limited to very small sample size. Here, we propose a new setup for X-ray holography based on a binary diffractive optical element (DOE), which forms at the same time the object illumination and the reference wave. This optic is located separately from the sample plane, which permits investigation of larger sample areas. Using an extended test sample, we demonstrate a resolution of 90 nm (half-pitch) at an undulator beamline at BESSY II. The new holography setup can be directly transferred to free electron laser sources enabling time-resolved nanoscale imaging for ultra-fast processes.

Bovine parafilariosis - New autochthonous cases from Germany and summary of recent reports from Europe.

Bovine parafilariosis is an emerging fly-borne disease in central Europe, characterized by seasonal occurrence of hemorrhagic exudations ('bleeding spots') from the end of winter to end of summer. In two cases from Germany reported here, one animal of a small herd in Bavaria and 20 animals on a farm in Baden-Württemberg presented bleeding spots from late March and late April 2020, respectively. Exudate samples from both cases were positive for larvated Parafilaria eggs. Examination of the skin and trimmed tissue after slaughter of the animal from Bavaria resulted in the collection of 11 nematodes (two males, eight females, one specimen in fragments). The animal's carcass presented typical yellow-greenish areas and bloody spots on the subcutaneous tissue of the flesh side of the skin. The nematodes were microscopically determined as Parafilaria bovicola. Basic morphometric measurements of two (one intact) male and six female nematodes are within the ranges of published data; length (male/female) 28.8/48.0-64.5 mm; width, 397.6 µm/430.7-527.6 µm; distance of cervical papillae to anterior end, 177.6/248.9-337.4; left spiculum/right spiculum (male), 365.3-379.4/149.5-180.3 µm; gubernaculum 45.0-48.1 µm; distance of vulva to anterior end (female), 37.3-66.0 mm. In order to gain information on P. bovicola in its vector, 91 cattle-visiting Musca autumnalis flies were collected from the affected animal in Bavaria (36 flies) and from co-pastured animals (55 flies) for PCR analysis and sequencing. A total of 14 flies were PCR-positive for filarial DNA, and sequencing of a fragment of the cox1 gene resulted in identification of P. bovicola (n = 10) and Thelazia gulosa (n = 5). This report presents further cases of bovine parafilariosis in Germany, provides morphometric data on male and female P. bovicola nematodes retrieved from cattle and identified DNA of P. bovicola and T.gulosa in M. autumnalis flies collected at a site of occurrence of bovine parafilariosis.

Correlative 3D cryo X-ray imaging reveals intracellular location and effect of designed antifibrotic protein-nanomaterial hybrids.

Revealing the intracellular location of novel therapeutic agents is paramount for the understanding of their effect at the cell ultrastructure level. Here, we apply a novel correlative cryo 3D imaging approach to determine the intracellular fate of a designed protein-nanomaterial hybrid with antifibrotic properties that shows great promise in mitigating myocardial fibrosis. Cryo 3D structured illumination microscopy (cryo-3D-SIM) pinpoints the location and cryo soft X-ray tomography (cryo-SXT) reveals the ultrastructural environment and subcellular localization of this nanomaterial with spatial correlation accuracy down to 70 nm in whole cells. This novel high resolution 3D cryo correlative approach unambiguously locates the nanomaterial after overnight treatment within multivesicular bodies which have been associated with endosomal trafficking events by confocal microscopy. Moreover, this approach allows assessing the cellular response towards the treatment by evaluating the morphological changes induced. This is especially relevant for the future usage of nanoformulations in clinical practices. This correlative super-resolution and X-ray imaging strategy joins high specificity, by the use of fluorescence, with high spatial resolution at 30 nm (half pitch) provided by cryo-SXT in whole cells, without the need of staining or fixation, and can be of particular benefit to locate specific molecules in the native cellular environment in bio-nanomedicine.

Occurrence of the giant liver fluke, Fascioloides magna, in sympatric wild ungulates in one area in the Upper Palatinate Forest (northeastern Bavaria, Germany).

Associated with the spreading in (north)western direction of Fascioloides magna from its historic endemic area in Bohemia with its cervid hosts, unusual noticeable hepatic lesions (black-colored tissue, hemorrhage) were observed in deer harvested in hunting grounds and one deer farm located in the Upper Palatinate Forest close to the border to the Czech Republic, initially in the years of 2007 and 2009, respectively. Confirmation of the suspected diagnosis of F. magna infection in October 2011 prompted investigations on the occurrence of "fascioloidosis" among wild ungulates in that locality. From October 2011 to January 2014, livers from 89 cervids and two wild boars were examined for flukes. Thirty-seven livers (40.6%) harbored F. magna: 17 of 21 red deer, nine of 24 sika deer, six of eight fallow deer, four of 36 roe deer, one of two wild boars. Fluke burdens ranged from 2 up to 151 in red deer, from 2 up to 37 in fallow deer, and from 1 up to 7 in sika deer and in roe deer; one fluke was recovered from the liver of one wild boar. No other parasites were recovered from the livers. The rate of recovery of F. magna differed significantly (p < 0.001) among the species of deer (red deer, 81.0%; sika deer, 37.5%; fallow deer, 75.0%; roe deer, 11.1%) and between the age groups (< 1 year: 22.2%, 1 to 2 years: 26.0%, and > 2 years: 70.0%, respectively). There was no association (p > 0.1) between the rate of recovery of F. magna and the sex of the combined 80 deer of ≥ 1 year of age (male: 41.8% and female: 31.4%). The occurrence of F. magna in the wild ungulates in the Upper Palatinate Forest area in northeastern Bavaria is of epidemiological importance for the further spreading of the parasite into Germany with migrating deer.

Efficacy of afoxolaner plus milbemycin oxime chewable tablets (NexGard Spectra®, Merial) against adult Ancylostoma ceylanicum hookworm, in dogs.

A fixed-combination chewable tablet incorporating afoxolaner plus milbemycin oxime (NexGard Spectra®, Merial) was tested in purpose-bred Beagle dogs for efficacy against adult Ancylostoma ceylanicum hookworms. Sixteen dogs were inoculated each by oral administration of approximately 500 infective larvae of A. ceylanicum. Seventeen days after inoculation, the dogs were weighed and allocated randomly to be treated with afoxolaner plus milbemycin oxime chewable tablets or to remain untreated. Commercial chewable tablets of different strength were combined to deliver doses as close as possible to the minimum effective dose of 2.5mg afoxolaner plus 0.5mg milbemycin oxime per kg body weight. Parasites were recovered and counted for determination of efficacy seven days after treatment. All eight dogs that had been left untreated were harboring adult A. ceylanicum (geometric mean, 317.8; range, 210-428) while only one and nine A. ceylanicum were recovered from two of the eight dogs treated with afoxolaner plus milbemycin oxime chewable tablets (geometric mean, 0.5; p<0.0001). Thus, 99.9% efficacy against induced infection of A. ceylanicum was obtained by the use of oral NexGard Spectra® at the minimum effective dose. Treatment with afoxolaner plus milbemycin oxime chewable tablets was well accepted and safe.

The intravenous and oral pharmacokinetics of afoxolaner and milbemycin oxime when used as a combination chewable parasiticide for dogs.

The pharmacokinetics of afoxolaner and milbemycin oxime (A3 and A4 forms) in dogs were evaluated following the oral administration of NexGard Spectra® (Merial), a fixed combination chewable formulation of these two active pharmaceutical ingredients. Absorption of actives was rapid at levels that provide the minimum effective doses of 2.5 mg/kg and 0.5 mg/kg of afoxolaner and milbemycin oxime, respectively. The time to maximum afoxolaner plasma concentrations (tmax ) was 2-4 h. The milbemycin tmax was 1-2 h. The terminal plasma half-life (t1/2 ) and the oral bioavailability were 14 ± 3 days and 88.3% for afoxolaner, 1.6 ± 0.4 days and 80.5% for milbemycin oxime A3 and 3.3 ± 1.4 days and 65.1% for milbemycin oxime A4. The volume of distribution (Vd ) and systemic clearance (Cls) were determined following an IV dose of afoxolaner or milbemycin oxime. The Vd was 2.6 ± 0.6, 2.7 ± 0.4 and 2.6 ± 0.6 L/kg for afoxolaner, milbemycin oxime A3 and milbemycin oxime A4, respectively. The Cls was 5.0 ± 1.2, 75 ± 22 and 41 ± 12 mL/h/kg for afoxolaner, milbemycin oxime A3 and milbemycin oxime A4, respectively. The pharmacokinetic profile for the combination of afoxolaner and milbemycin oxime supports the rapid onset and a sustained efficacy for afoxolaner against ectoparasites and the known endoparasitic activity of milbemycin oxime.

Ivermectin treatment of bovine psoroptic mange: effects on serum chemistry, hematology, organ weights, and leather quality.

Psoroptic mange is a skin disease which may result in serious health and welfare problems and important economic losses. Apart from the effect on weight gain, little information is available concerning other responses of the organism consequent to the successful therapy of bovine psoroptic mange. Accordingly, serum chemistry, hematology, organ weights, and leather quality of young bulls with experimentally induced clinical Psoroptes ovis mange and treated with either ivermectin long-acting injection (IVM LAI; IVOMEC(®) GOLD, Merial) or saline (n = 16 each) were examined 8 weeks after treatment when all IVM LAI-treated bulls were free of live P. ovis mites while the saline-treated bulls maintained clinical mange. IVM LAI-treated bulls had higher (p < 0.05) alkaline phosphatase, creatinine, cholesterol, glucose, and albumin levels and lower (p < 0.01) total protein and ß- and γ-globulin levels than the saline-treated bulls. Complete blood counts revealed higher leukocyte counts associated with higher eosinophil counts and higher platelet counts in the saline-treated compared to the IVM LAI-treated bulls (p < 0.01). Correlating with body weight, the warm carcass weight of the saline-treated bulls was lower than that of the IVM LAI-treated bulls (p < 0.05). Absolute and relative (organ weight divided by body weight) weights of the spleen, thymus, omental fat, and perirenal fat were higher (p < 0.01) for the IVM LAI-treated bulls than for the saline-treated bulls, while the IVM LAI-treated bulls had lower (p < 0.05) absolute and relative weights of the liver, adrenal glands, and selected lymph nodes than the saline-treated bulls. The leathers produced from the IVM LAI-treated bulls showed significantly (p < 0.001) less severe gouging or etching than leathers from the saline-treated bulls, and significantly (p < 0.05) more leather from the IVM LAI-treated bulls was of usable quality than the size of leather from the saline-treated bulls. Overall, these findings provided evidence that many changes, which are indicative of impaired protein and energy metabolism, immune system function, and performance resultant from clinical psoroptic mange, improved substantially within 8 weeks of successful treatment with injectable ivermectin.

Multilocus sequence typing of canine Giardia duodenalis from South Eastern European countries.

Giardia duodenalis is a worldwide occurring protozoan that can infect various mammalian hosts. While living conditions are getting closer between pet animals and owners, there is discussion whether dogs may contribute to the transmission of these pathogens to humans. The present study was conducted in order to identify the Giardia assemblages in dogs from South Eastern Europe. For this purpose, 1645 faecal samples of household and shelter dogs from Albania, Bulgaria, Hungary, Macedonia, Romania and Serbia were tested for Giardia coproantigen by enzyme-linked immunosorbent assay (ELISA). A subset of 107 faecal samples demonstrating Giardia cysts by direct immunofluorescence assay (IFA) or microscopy (15-22 per country) plus 26 IFA-positive canine faecal samples from Croatia were used for DNA extraction and multilocus sequence typing with nested PCRs targeting five different gene loci: SSU rRNA, ITS1-5.8S-ITS2, beta giardin (bg), glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi). One third (33.7%) of the samples tested positive for Giardia antigen in the coproantigen ELISA. Shelter dogs were infected more frequently than household dogs (57.2 vs. 29.7%, p < 0.01). Amplification was obtained in 82.0, 12.8, 11.3, 1.5, and 31.6%, of the investigated samples at the SSU rRNA, bg, gdh and tpi loci and the ITS1-5.8S-ITS2 region, respectively. The dog-specific assemblages C and D were identified in 50 and 68 samples, respectively. The results demonstrate that G. duodenalis should be considered as a common parasite in dogs from South Eastern Europe. However, there was no evidence for zoonotic Giardia assemblages in the investigated canine subpopulation.

Acaricide treatment prevents adrenocortical hyperplasia as a long-term stress reaction to psoroptic mange in cattle.

In cattle, infestation with Psoroptes ovis mites may cause severe dermatitis (psoroptic mange) which compromises the health and welfare of the animals and may lead to significant economic losses. To investigate yet undocumented effects of psoroptic mange mite infestations and how successful therapy promotes animal health, the present study examined alterations of the skin, lymph nodes and adrenal glands of P. ovis infested Fleckvieh (Simmental) bulls treated with either ivermectin long-acting injection (IVM LAI; IVOMEC(®) GOLD, Merial; 3.15% ivermectin w/v) or saline (n=16 each). Approximately 8 weeks subsequent to experimental infestation with P. ovis, the bulls had developed mange and were administered either IVM LAI or saline once at 1 mL/50 kg body weight by subcutaneous injection. Mite counts were conducted in weekly intervals for determination of efficacy of treatment, and following humane euthanasia of the animals 8 weeks after treatment, skin samples from affected (mangy or previously mangy) and unaffected areas, prescapular lymph nodes and adrenal glands were collected for gross and pathohistological examination. In addition, four age-matching, uninfested Simmental bulls were sampled as controls for comparison. No P. ovis mites were detected on any IVM LAI-treated bull after 28 days following treatment whereas saline-treated bulls maintained infestation throughout the study. At sampling (approximately 16 weeks after experimental infestation and 8 weeks following saline or IVM LAI treatment), saline-treated bulls displayed a severe, exsudative dermatitis with significantly increased skin thickness and inflammatory cell infiltration, significantly enlarged, hyperplastic prescapular lymph nodes, as well as significantly increased adrenal gland weights and volumes as compared to P. ovis-infested, IVM LAI-treated bulls and uninfested controls. Quantitative stereological analysis revealed that the adrenal gland enlargement in P. ovis-infested, saline-treated bulls was due to a selective increase of the volume of the zona fasciculata in the adrenal cortex. Compared to uninfested controls and P. ovis-infested, IVM LAI-treated bulls, the number of epithelial cells in the zona fasciculata was significantly increased in P. ovis-infested, saline-treated bulls, while the zona fasciculata cell volumes did not differ between the three groups of cattle. While the single point determination of serum cortisol concentrations did not reveal significant differences between the three groups of cattle at tissue sampling, the hyperplastic growth of the adrenal cortex in the P. ovis-infested, saline-treated bulls provides morphologic evidence that a chronic stress reaction is one consequence of mange mite infestations that can be prevented by efficacious acaricidal treatment.

Activity of ivermectin long-acting injectable (IVOMEC(®) GOLD) in first-season grazing cattle exposed to natural challenge conditions in Germany.

The persistent activity of ivermectin long-acting injection (IVM LAI; IVOMEC® GOLD, Merial; 3.15% ivermectin w/v) against nematode infections of cattle was evaluated under natural challenge conditions. Seventy nematode-free Brown Swiss calves were blocked by pre-treatment bodyweight and allocated randomly to seven groups of 10 animals each: saline (control) at 1 mL/50 kg bodyweight once on day 0 or IVM LAI at 1 mL/50 kg bodyweight (630 mcg IVM/kg) on either days 0, 7, 14, 21, 28, or 35. After housing until day 35, calves were grazed as one herd on a naturally contaminated pasture for 42 days. Calves were then weighed and housed for 4 weeks before being necropsied for parasite counting. Treatment with IVM LAI prevented the establishment (>90%, p < 0.05) of Dictyocaulus viviparus (100%), Bunostomum phlebotomum (100 %), Haemonchus contortus (98.6%), Ostertagia ostertagi/lyrata (94.9%), and Oesophagostomum radiatum (93.3%) for at least 77 days; Ostertagia leptospicularis (99.1%) for 63 days; Cooperia punctata (97.7%), Trichostrongylus axei (96.5%), and Ostertagia spp. inhibited larvae 4 (93.3%) for 56 days; Cooperia oncophora/surnabada (96.9%), Trichuris discolor (93.6%), and Cooperia spp. inhibited larvae 4 (98.8%); and Nematodirus spp. inhibited larvae 4 (97.1%) for 42 days. Calves of groups treated with IVM LAI had significantly (p < 0.001) higher days 0 to 77 weight gains than the saline-treated controls (28.40-39.25 vs 2.60 kg); the weight gains of the IVM LAI-treated groups, however, were not different from one another (p > 0.3). This study demonstrated a very high efficacy of IVOMEC® GOLD in preventing the establishment of a wide range of bovine nematodes for extended periods of time which was associated with a significant benefit to productivity in terms of weight gain.

An eprinomectin extended-release injection formulation providing nematode control in cattle for up to 150 days.

A series of 10 dose confirmation studies was conducted to evaluate the persistent activity of an extended-release injectable (ERI) formulation of eprinomectin against single point challenge infections of gastrointestinal and pulmonary nematodes of cattle. The formulation, selected based on the optimal combination of high nematode efficacy, appropriate plasma profile, and satisfactory tissue residue levels, includes 5% poly(D,L-lactide-co-glycolic)acid (PLGA) and is designed to deliver eprinomectin at a dose of 1.0mg/kg bodyweight. Individual studies, included 16-30 cattle blocked based on pre-treatment bodyweight and randomly allocated to treatment with either ERI vehicle or saline (control), or the selected Eprinomectin ERI formulation. Treatments were administered once at a dose volume of 1 mL/50 kg bodyweight by subcutaneous injection in front of the shoulder. In each study, cattle were challenged with a combination of infective stages of gastrointestinal and/or pulmonary nematodes 100, 120 or 150 days after treatment and were processed for parasite recovery according to standard techniques 25-30 days after challenge. Based on parasite counts, Eprinomectin ERI (1mg eprinomectin/kg bodyweight) provided >90% efficacy (p<0.05) against challenge with Cooperia oncophora and Cooperia surnabada at 100 days after treatment; against challenge with Ostertagia ostertagi, Ostertagia lyrata, Ostertagia leptospicularis, Ostertagia circumcincta, Ostertagia trifurcata, Trichostrongylus axei, and Cooperia punctata at 120 days after treatment; and against challenge with Haemonchus contortus, Bunostomum phlebotomum, Oesophagostomum radiatum and Dictyocaulus viviparus at 150 days after treatment. Results of a study to evaluate eprinomectin plasma levels in cattle treated with the Eprinomectin ERI formulation reveal a characteristic second plasma concentration peak and a profile commensurate with the duration of efficacy. These results confirm that the Eprinomectin ERI formulation can provide high levels of parasite control against a range of nematodes of cattle for up to 5 months following a single treatment.

The efficacy of eprinomectin extended-release injection against naturally acquired nematode parasites of cattle, with special regard to inhibited fourth-stage Ostertagia larvae.

The efficacy of eprinomectin in an extended-release injection (ERI) formulation in the treatment of cattle harboring naturally acquired nematode populations (including inhibited nematodes) was evaluated. Five studies were conducted under a similar protocol in the USA, the UK, and in Germany. All study animals were infected by grazing naturally contaminated pastures. The adequacy of pasture infectivity was confirmed by examining tracer calves prior to allocation and treatment of the study animals. The cattle were of various breeds or crosses, weighing 79-491 kg, and aged approximately 6-15 months. In each study, 20 animals were infected by grazing, and then removed from pasture and housed in a manner to preclude further nematode infections for 8-16 days until treatment. Animals were blocked based on descending pre-treatment body weight and randomly allocated to one of two treatments: ERI vehicle (control) at 1 mL/50 kg body weight or eprinomectin 5% (w/v) ERI at 1 mL/50 kg body weight (1.0 mg eprinomectin/kg). Treatments were administered once on Day 0 by subcutaneous injection in front of the shoulder. For parasite recovery and count, all study animals were humanely euthanized 14/15 days after treatment. Cattle treated with eprinomectin ERI had significantly (p<0.05) fewer of the following nematodes than the controls with overall reduction of parasite counts of ≥94%: adult Dictyocaulus viviparus, Capillaria spp., Cooperia oncophora, Cooperia pectinata, Cooperia punctata, Cooperia surnabada, Haemonchus placei, Nematodirus helvetianus, Oesophagostomum radiatum, Ostertagia lyrata, Ostertagia ostertagi, Trichostrongylus axei, Trichostrongylus colubriformis, Trichuris discolor, Trichuris skrjabini, and Trichuris spp.; developing fourth-stage larvae of Ostertagia spp. and Trichostrongylus spp.; and inhibited fourth-stage larvae of Cooperia spp., Haemonchus spp., Nematodirus spp., Oesophagostomum spp., Ostertagia spp., and Trichostrongylus spp. Animal treatments were well accepted, with no adverse reactions to treatment observed in any study animals. The results of this series of controlled studies demonstrated high therapeutic efficacy and acceptability of eprinomectin ERI against pulmonary nematodes and a wide range of gastrointestinal parasitic infections, including inhibited gastrointestinal nematodes, in cattle.

The treatment of bovine sarcoptic mange (Sarcoptes scabiei var. bovis) using eprinomectin extended-release injection.

The efficacy of eprinomectin in an extended-release injection (ERI) formulation was evaluated in cattle harbouring induced infestations of Sarcoptes scabiei var. bovis (sarcoptic mange) in three studies conducted in Germany (two studies) and Austria (one study). A total of 44 cattle were included in the studies, 12 in one study and 16 in each of the other two studies. Approximately eight weeks following initial induced infestation, cattle in each study were formed into replicates of two animals each on the basis of pre-treatment bodyweights. Within replicates the animals were randomly allocated to one of two treatments: ERI vehicle (control) or Eprinomectin 5% (w/v) ERI (1.0 mg eprinomectin/kg). Treatments were administered at 1 mL/50 kg bodyweight by subcutaneous injection in front of the shoulder once on day 0. The number of live mites in skin scrapings was determined prior to treatment and at weekly intervals for eight weeks after treatment. Severity of skin lesions was evaluated and scored when skin scrapings were taken. In all studies, animals were weighed before infestation and again prior to and at 56 days after treatment. Mite counts for treated cattle were significantly (p<0.05) lower than counts for controls from Day 7 onwards. Cattle treated with Eprinomectin ERI were Sarcoptes mite-free from seven, 21 or 28 days post-treatment to the end of the study in the three studies, and lesions regressed accordingly. Mean weight gain over the post-treatment period was significantly higher for treated cattle than for controls in two studies. All animals accepted the treatment well.

The efficacy of eprinomectin extended-release injection against Hypoderma spp. (Diptera: Oestridae) in cattle.

The efficacy of eprinomectin in an extended-release injection (ERI) formulation was determined in cattle harboring naturally acquired infestations of first- or second- and third-stage larvae of Hypoderma spp. in three studies conducted according to the same protocol in the USA (two studies) and Germany (one study). Thirty cattle sourced from herds with a history of Hypoderma infestation were included in each study. Cattle were formed into replicates of three animals each on the basis of pre-treatment anti-Hypoderma antibody titers. Within replicates each animal was randomly allocated to one of the following treatments: ERI vehicle (control) at 1 mL/50 kg bodyweight, administered once on Day 0; Eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg), administered once on Day 0 (when larvae were expected to be first instars); or Eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg), administered once when larvae were second or third instars (study dependent, Day 73, 119, or 140). Treatments were administered by subcutaneous injection in front of the shoulder. In all studies, emerging and/or expressed Hypoderma larvae were recovered, speciated, and counted and viability was determined. Eprinomectin LAI treatment was 100% (p<0.05) efficacious against first- and second- or third-stage larvae of Hypoderma bovis (two studies) and Hypoderma lineatum (one study). All animals accepted the treatment well. No adverse reaction to treatments was observed in any animal in any study.

Nematode burdens of pastured cattle treated once at turnout with eprinomectin extended-release injection.

The efficacy of eprinomectin in an extended-release injection (ERI) formulation was evaluated against infections with third-stage larvae or eggs of gastrointestinal and pulmonary nematodes in cattle under 120-day natural challenge conditions in a series of five studies conducted in the USA (three studies) and in Europe (two studies). For each study, 30 nematode-free (four studies) or 30 cattle harboring naturally acquired nematode infections (one study) were included. The cattle were of various breeds or crosses, weighed 107.5-273 kg prior to treatment and aged approximately 4-11 months. For each study, animals were blocked based on pre-treatment bodyweight and then randomly allocated to treatment: ERI vehicle (control) at 1 mL/50 kg bodyweight or Eprinomectin 5% (w/v) ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg) for a total of 15 and 15 animals in each group. Treatments were administered once on Day 0 by subcutaneous injection in front of the shoulder. In each study, all animals grazed one naturally contaminated pasture for 120 days. At regular intervals during the studies, fecal samples from all cattle were examined for nematode egg and larval counts. In four studies pairs of tracer cattle were used to monitor pasture infectivity at 28-day intervals before and/or during the grazing period. All calves were weighed before turnout onto pasture and at regular intervals until housing on Day 120. For parasite recovery, all study animals were humanely euthanized 27-30 days after removal from pasture. Cattle treated with Eprinomectin ERI had significantly (p<0.05) fewer strongylid eggs (≤1 egg per gram; egg count reduction≥94%) than the control cattle and zero lungworm larvae at each post-treatment time point. At euthanasia, cattle treated with Eprinomectin ERI had significantly (p<0.05) fewer of the following nematodes than the ERI vehicle-treated (control) cattle with overall reduction of nematode counts by >92%: Dictyocaulus viviparus (adults and fourth-stage larvae (L4), Bunostomum phlebotomum, Cooperia curticei, Cooperia oncophora, Cooperia punctata, Cooperia surnabada, Cooperia spp. inhibited L4, Haemonchus contortus, Haemonchus placei, Haemonchus spp. inhibited L4, Nematodirus helvetianus, Nematodirus spp. inhibited L4, Oesophagostomum radiatum, Oesophagostomum spp. inhibited L4, Ostertagia leptospicularis, Ostertagia lyrata, Ostertagia ostertagi, Ostertagia spp. inhibited L4, Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus spp. inhibited L4, Trichuris discolor, and Trichuris ovis. Over the 120-day grazing period, Eprinomectin ERI-treated cattle gained between 4.8 kg and 31 kg more weight than the controls. This weight gain advantage was significant (p<0.05) in three studies. All animals accepted the treatment well. No adverse reaction to treatment was observed in any animal in any study.