The efficacy of oxfendazole against natural infections of nematodes & cestodes in sheep

Oxfendazole (5 mg/kg) was tested against natural infections of nematodes and cestodes in sheep in three experiments.

It was 100% effective against all stages of Ostertagia sp., Nematodirus spathiger, Oesophagostomum venulosum, Chabertia ovina, Moniezia expansa, immature 5th stage and adult Cooperia curticei and 4th stage Trichostrongylus sp. Efficacy was 99%–100% against immature 5th stage and adult Trichostrongylus sp., 67.8%and 91.6% against adult Strongyloides sp., 80.7%and 89.5% against immature 5th stage Trichuris ovis and 74% and 79% against Trichuris ovis.     

Evaluation of four forms of oxfendazole against nematodes of cattle.

Oxfendazole, methyl [5-(phenylsulfinyl)-1H-benzimidazol-2-yl] carbamate, was evaluated in calves naturally infected with endoparasites. The compound was used as a drench, a paste, a bolus, and as top-dress crumbles at a dosage of 2.5 mg/kg of body weight. The four formulations produced similar effects and were 99% to 100% effective in removing the following adult parasite genera: Haemonchus, Ostertagia, Trichostrongylus. Cooperia, Bunostomum, Oesophagostomum, and Dictyocaulus. Mean efficacy against Trichuris spp varied from 87% to 95%, depending on the formulation used.     

Dose titration of oxfendazole against common nematodes of swine.

Oxfendazole, a benzimidazole carbamate, was administered as a 0.5% feed additive to 88 pigs naturally infected with two to four nematode species. Dose rates of 1.5 mg/kg of body weight, 3.0 mg/kg, 3.75 mg/kg, 4.5 mg/kg, 6.75 mg/kg, or 9.0 mg/kg were 100% efficacious against Oesophagostomum dentatum and 99.2% to 100% effective against Ascaris suum. Dose rates of 4.5 mg/kg, 6.75 mg/kg, and 9.0 mg/kg were 92.7%, 98.9%, and 99.5% effective, respectively, against mixed populations of Metastrongylus apri and M pudendotectus. Results were variable with Trichuris suis infections. Efficacy was based on the number of nematodes recovered at necropsy. Palatability and acceptability of the feed additive were good, and adverse reactions following administration were not observed.     

A morantel sustained-release bolus for the control of gastro-intestinal nematodes in grazing calves

Prophylactic (summer) and/or therapeutic (autumn) administrations of an intra-ruminal sustained-release bolus (MSRB) containing morantel tartrate were compared for the control of gastro-intestinal nematodes in grazing dairy calves over an 8-month period (December to August). The MSRB was designed to release morantel tartrate at 150 mg/day for 90 days.

Treated and untreated groups of calves grazed separate replicated pastures. Both groups of calves receiving the MSRB at the beginning of summer showed a significant mean liveweight advantage (17.7 kg and 20.7 kg for the summer and summer/autumn treated groups, respectively) at the end of the trial period, when compared with untreated calves. The liveweight advantage of calves receiving the MSRB in autumn only (6.5 kg) was not significantly different from that of the controls.

Both the summer and autumn administrations of the MSRB prevented the accumulation of Pre-Type II burdens of Ostertagia spp.

Retention rates of the MSRB were high and chemical analysis of faecal samples indicated a fairly constant release of the anthelmintic over the predicted 90-day period.

The results indicate that the MSRB is potentially useful for the control of gastro-intestinal nematodes, and particularly for the production of ’safe’ pasture. The MSRB could provide an effective alternative to integrated control based primarily on grazing management.     

Efficacy of a single high oxfendazole dose against gastrointestinal nematodes in naturally infected pigs

The goal of the current experiment was to assess the clinical efficacy of oxfendazole (OFZ) administered as a single oral dose (30 mg/kg) to pigs naturally parasitized with Ascaris suum, Oesophagostomum spp., Metastrongylus spp. and Trichuris suis. Thirty-six local ecotype piglets were divided into three independent experiments, named I, II and III (n = 12 each), respectively. Each experiment involved two different groups (n = 6): Untreated Control and OFZ treated. Animals were naturally parasitized with A. suum (Experiments I, II and III), Oesophagostomum spp. (Experiments I and II), T. suis (Experiments II and III) and Metastrongylus spp. (Experiment I). Pigs in the treated group received OFZ (Synanthic^®, Merial Ltd., 9.06% suspension) orally at 30 mg/kg dose. At five (5) days post-treatment, animals were sacrificed and the clinical efficacy of the OFZ treatment was established following the currently available WAAVP guidelines for a controlled efficacy test. None of the animals involved in this experiment showed any adverse events during the study. OFZ treatment given as a single 30 mg/kg oral dose showed a 100% efficacy against all the nematode parasites present in the three experiments. In conclusion, under the current experimental conditions, OFZ orally administered to naturally parasitized piglets at a single dose of 30 mg/kg was safe and highly efficacious (100%) against adult stages of A. suum, Oesophagostomum spp., T. suis and Metastrongylus spp.     

Evaluation of lasalocid and decoquinate against coccidiosis resulting from natural exposure in weaned dairy calves

Eighteen female Holstein calves, raised as natural herd additions under conditions typical of a well-managed midwestern United States dairy farm, were used in a natural-exposure study to determine the anticoccidial efficacies of lasalocid and decoquinate. Calves were allotted to 6 treatment blocks of 3 calves each as they were weaned. Within each block, calves were randomly assigned to be given either lasalocid or decoquinate or to remain as a nonmedicated control. Calves were given medication for 90 days and remained separated from other calves for 120 days. Adjusted weight gains were consistently greater in calves that were given medication; however, differences were not statistically significant. Fecal specimens were obtained from calves at weekly intervals during the study. Overall, oocyst shedding was low. During the medication period, quantitative mean fecal shedding of oocysts was reduced eightfold in calves given decoquinate and four-fold in calves given lasalocid, as compared with nonmedicated control calves. During the period following the medication period, calves that had been controls shed fewer oocysts than did calves that had previously been given medication. A pairwise comparison of the proportion of specimens that were oocyst-positive was made to assess qualitative oocyst shedding among treatment groups. During the medication period, qualitative oocyst shedding (all species, Eimeria bovis, E zuernii, species other than E bovis and E zuernii) was greater in controls than in either lasalocid-or decoquinate-treated groups. Like-wise, lasalocid-medicated calves shed oocysts more frequently than did the decoquinate-medicated group. After medication, qualitative findings were reversed. Little diarrhea was noticed in treatment or control calves during the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of Cydectin moxidectin 1% injectable against experimental infections of Dictyocaulus viviparus and Bunostomum phlebotomum superimposed on natural gastrointestinal infections in calves.

Twenty male Holstein calves averaging 105 kg in weight and naturally infected with gastrointestinal nematodes and small numbers of lungworm and hookworm, were given experimental infections with the two latter species to provide adult and larval stages for anthelmintic evaluation. Following random allotment, one group of 10 calves was injected subcutaneously with moxidectin at a dosage of 0.2 mg kg-1 of body weight. A second group of 10 was injected subcutaneously with unmedicated blank vehicle at a dosage of 1 ml per 50 kg of body weight. Fecal samples were examined before treatment and at 7 and 13 days after treatment. The 20 calves were necropsied for worm recovery at 13 and 14 days after treatment. All calves were positive for lungworm and hookworm on the treatment date. Treatment was 100% effective in elimination of hookworm eggs and lungworm larvae and 99.9% in reducing total egg counts at both 7 and 13 days after treatment. Moxidectin was 100% effective (P less than 0.01) in eliminating the following 11 species of nematodes. Dictyocaulus viviparus mature and immature adults (E5), Bunostomum phlebotomum adults and L4, Ostertagia ostertagi adults and early L4, Ostertagia lyrata adult males, Haemonchus placei adults. Trichostrongylus axei adults, Cooperia spp., including Cooperia punctata, Cooperia spatulata, and Cooperia pectinata adults, Oesophagostomum radiatum adults and Trichuris discolor adults. No adverse reactions to moxidectin treatment were observed.     

Efficacy of a topical formulation of ivermectin against naturally acquired gastro-intestinal nematodes in weaner cattle

The efficacy of a topical formulation of ivermectin against naturally acquired gastro-intestinal nematodes in weaner cattle was evaluated. At slaughter, 14-15 days after treatment, burdens of Ostertagia spp, Trichostrongylus axei and Oesophagostomum radiatum were significantly lower in the treated calves than in the untreated controls (p<0.01). Efficacies (based on geometric mean worm burdens of treated and control groups) were 99.6%, 95.1% and 100% respectively. The sizes of the Cooperia spp and Trichuris ovis burdens in the treated group did not differ significantly at the 5% level of confidence from those in the control group.     

Pathogenesis of simulated natural infections with Ostertagia ostertagi in calves

The possibility of a mucosal hypersensitivity reaction and its relationship to the pathogenesis of simulated natural infections with Ostertagia ostertagi were studied in calves. Four groups of 4 calves each were used. One group was used as noninfected control; a 2nd group was given increasing doses of infective larvae; a 3rd group was given increasing doses of larvae and these were removed by succeeding treatment with an anthelmintic; and a 4th group was given an initial dose of larvae which was then eliminated with an anthelmintic. All calves given larvae became sensitized, as shown by an intradermal skin test. The continuously infected calves had significantly (P less than 0.05) higher fecal egg counts, eosinophil counts, plasma pepsinogen values, and worm burdens and significantly (P less than 0.05) lower lymphocyte counts than did the other groups of calves. These animals also had the most extensive mucosal pathologic changes. The group given intermittent larval challenge exposures followed by an anthelmintic showed decreased lymphocyte values, but these were not significant. Plasma pepsinogen values of this group increased between every challenge exposure and treatment, a 3-day period. This indicated that a mucosal hypersensitivity reaction had occurred in these calves at these times, because they were shown to have been sensitized, and challenge-exposure infections were not present for sufficient time to have produced direct pathologic effects. It therefore seems that a part of the pathologic changes in O ostertagi infections may be the result of the continuous challenge exposure experienced by the animals through a constant intake of larvae from pasture and the intestinal reaction to this challenge exposure.     

Persistent efficacy of doramectin pour-on against artificially induced infections of nematodes in cattle.

Two studies were conducted to determine the persistent efficacy of doramectin pour-on against an artificial, trickle challenge of mixed nematodes in calves. In each study, 42, 4-8 months old calves were randomly assigned into four groups of 10 animals each (T1-T4), plus two larval-viability monitor animals. All animals were treated with fenbendazole (10 mg kg(-1)) 14 days prior to the start of the study to clear any existing infection. Doramectin pour-on at 500 microg kg(-1) was used on each animal in Groups T2, T3, and T4 with intervals of 1 week (Day 0, 7, and 14, respectively). Calves in Group T1 were treated with saline solution on Day 0 and at the same volumetric rate (1 ml 10 kg(-1)) as the doramectin treated animals. All treatments were applied in a single passage along the midline of the back, from the withers to the tailhead. Subsequently, trickle inoculations with infective larvae were administered to all calves for 22 consecutive days (Days 14-35). Doramectin pour-on provided > or = 91.9% efficacy against challenge with Dictyocaulus viviparus, Haemonchus spp., and Ostertagia ostertagi for up to 35 days post-treatment and against challenge with Cooperia oncophora, Cooperia punctata, and Oesophagostomum radiatum for up to 28 days post-treatment.     

Evaluation of the efficacy of oxfendazole against larval and adult Toxascaris leonina in the dog

The efficacy of oxfendazole, given at a dose rate of 10 mg/kg for three consecutive days, against adult and larval Toxascaris leonina was determined in four litters of naturally infected adolescent greyhounds. When administered to five dogs 10 weeks after exposure to infectiori, oxfendazole gave an efficacy value of 100 per cent as determined by comparison of the numbers of adult worms expelled and the numbers remaining at subsequent post mortem examination. When medication was given only five weeks after exposure to infection, the number of immature T. leonina in 10 treated pups was found to be reduced by 92-1 per cent as compared with 10 matched, untreated controls. Incidental infections of Toxocara canis and Uncinaria stenocephala were adequately controlled but the treatment was less effective against Trichuris vulpis and Strongyloides species.     

Anthelmintic activities of B1a fraction of avermectin against gastrointestinal nematodes in calves

Anthelmintic activities of the B1a fraction of avermectin were evaluated in a controlled experiment. Twenty 12-week-old calves artificially infected with gastrointestinal nematodes were allotted to four groups. Calves in group 1 were used as nonmedicated controls; other calves in groups 2, 3, and 4 were given (orally) B1a avermectin at dosage levels of 50, 100, and 200 microgram/kg of body weight, respectively. These treatments were given 35 days after calves were inoculated with infective nematode larvae. In groups 2, 3, and 4, overall reductions (based on geometric means) were 98.6%, 98.7%, and 98.4%, respectively. These reductions were highly significantly different (P less than 0.01) from the control calves. Nematodes in the calves were Haemonchus contortus. Ostertagia ostertagi, Trichostrongylus axei, T colubriformis, Cooperia oncophora, C punctata, and Oesophagostomum radiatum.     

Antigenic structure of nematodes and prospects for vaccination against helminth infections

Domestic animals may become resistant to parasites. There have been many studies of the nature and role of the antigens involved in this immunological reaction and the results are presented in this paper.The antigens may be the tissues of the worm itself (somatic antigens) or its secretions (metabolic antigens). Resistance to attack by parasites may be induced by using either live worms (very small numbers of parasites or irradiated larvae) or homogenised whole worms or extracts of their secretions. In favourable cases the administration of antigens may vaccinate the animal but it may also produce a state of tolerance.A precise knowledge and mastery of these factors should lead to the successful vaccination of animals against their parasites.

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Kurzfassung Bei Parasitentragern entwickelt sich häufig ein Resistenzzustand; Natur und Rolle der Antigene, die bei Immunitätsreaktionen beteiligt sind, haben viele Untersuchungen angeregt, deren Ergebnisse hier dargestellt werden. Die Antigene werden entweder durch die Gewebe des Fadenwurmes selbst (somatische Antigene) oder durch seine Ausscheidungen (metabolische Antigene) repräsentiert. Resistenz (Verseuchung mit einer ganz kleinen Menge von Parasiten oder mit bestrahlten Larven), mit ganzen zermalmten Würmern, oder mit Extrakten ihrer Ausscheidungen erreicht werden. Die Verabreichung von Antigenen Kann in günstigen Fällen zu einer Vakzination oder zu einem Tolleranzzustand führen. Genaue Kenntnisse und die Beherrschung dieser Faktoren sollten zu einer Vakzination der Tiere gegen ihre Parasiten führen.

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Resume Un état de résistance se développe chez les animaux porteurs de parasites; la nature et le rôle des antigènes intervenant dans la réaction immunitaire a suscité de nombreux travaux dont les résultats sont exposés ici.Les antigènes sont représentés par les tissus du ver luimême (antigènes somatiques) ou par ses excrétions (antigènes métaboliques). La résistance à l'agression parasitaire peut être obtenue en employant soit des vers vivants (infestation par de très petites quantités de parasites, ou par des larves irradiées) soit des broyats de vers totaux ou des extraits de leurs sécrétions.L'administration d'antigènes peut conduire a une vaccination dans les cas favorables mais aussi à un état de tolérance.La connaissance exacte et la maitrise de ces facteurs, examinés ici, devraient conduire a la vaccination des animaux contre leurs parasites.

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Riassunto Gli animali portatori di parassiti sviluppano una resistenza al parassita stesso; la natura ed il ruolo degli antigeni che intervengono nella reazione immunitaira sono l'argomento di numerosi lavori i cui risultati sono que esposti.Gli antigeni sono costituiti dai tessuti del verme stesso (antigeni somatici), oppure dai suoi escreti (antigeni metabolici). La resistenza all'aggressione parassitaria puo essere ottenuta sia impiegando vermi vivi (infezione con quantita di parassiti molto piccole o con larve irradiate), sia ammassi di vermi interi o estratti dai loro secreti. La somministrazione di antigeni puo portare nei casi favorevoli ad una vaccinazione ma anche ad uno stato di tolleranza. La conoscenza esatta ed il controllo dei fattori qui esaminati, dovrebbero portare alla vaccinazione degli animali control loro parassiti.

     

Uredofos: anthelmintic activity against nematodes and cestodes in dogs with naturally occurring infections.

A new broad-spectrum anthelmintic, uredofos, was tested in 146 dogs by single and multiple oral dosing. Single doses of 100 and 50 (but not 25) mg/kg were totally effective in removing Dipylidium caninum and Taenia spp from 46 dogs with infections of tapeworms. Among groups of 15 to 20 dogs, the average percentage efficacies against Toxocara canis for single soese of 100, 50, and 25 mg/kg were 98, 96, and 81%, respectively. The average percentage of efficacies against hookworm (Ancylostoma caninum) were greater than 96% in dogs treated with single doses of 100, 50, or 25 mg/kg and were 100% in the 35 dogs given 2 or 3 treatments (24-hour intervals) at dose levels of either 25 or 50 mg/kg. The whipworm, Trichuris vulpis, was not efficaciously eliminated by single doses of 25, 50, and 100 mg/kg (av percentage of efficacies of 30, 35, and 71%, respectively). Efficacy against T vulpis markedly improved when 2 doses were given at a 24-hour interval (av percentage of efficacies were 89% at dose level of 25 mg/kg and 99% at dose level of 50 mg/kg). At either dose (25 or 50 mg/kg), 3 daily treatments were no more efficacious against whipworms than were 2 doses. There was no evidence of drug toxicosis in any dogs tested. It was concluded that uredofos is highly effective against canine tapeworms, ascarids, and hookworms when given as a single dose of 50 mg/kg and against whipworm when given at dose level of 50 mg/kg/day for 2 days.     

Efficacy of the morantel sustained release trilaminate matrix against gastrointestinal nematodes in beef calves

The effectiveness of the morantel sustained release trilaminate (MSRT) in controlling gastrointestinal nematodes through a grazing season was evaluated using 60 yearling beef stocker calves randomly divided into 2 groups of 30 animals each. In April 1985, the calves comprising the treatment group each received an MSRT designed to release morantel tartrate continuously for 90 days while those of the control group remained unmedicated. All animals were weighed and samples of rectal feces were taken at 14-day intervals, beginning on Day 0, until trial termination (Day 168). At trial termination, 10 control and 10 treated calves were necropsied for recovery of gastrointestinal nematodes. Three sets of parasite-na?ve tracer calves were utilized to evaluate the initial, interim and final levels of pasture contamination by nematode larvae. Overall, the use of the MSRT resulted in a 75.5% reduction (P less than 0.001) in output of nematode eggs from the principals, an 81.8% reduction (P less than 0.001) in numbers of gastrointestinal nematodes in principals (at trial termination), and a 96.9% reduction (P less than 0.05) of pasture larval nematode contamination (as indirectly indicated by parasite burdens in tracer calves). The mean weight advantage of treated calves was 16.6 kg per head (P less than 0.001).     

A new polyvalent vaccine against enteral infections in newborn calves

The most frequent microbial causative agents of massive diarrheas in new-born calves kept on large cattle farms in the CSSR are rotaviruses, coronaviruses and enterotoxigenic strains of E. coli, manifesting themselves as complicated virus-bacterial infections. An inactivated polyvalent adjuvant vaccine has been developed for the prevention and specific prophylaxis of these enteral infections; the vaccine contains bovine rotavirus, bovine coronavirus and three enterotoxigenic serotypes of E. coli with protective antigen K 99. The rotavirus and coronavirus are propagated on the stable cellular line MDBK and inactivated with 0.2% formalin, the Escherichia strains are submersed in the MINCA culture medium during their cultivation and inactivated with 0.5% formalin. The vaccine was prepared as a blend of the same amounts of rotavirus and coronavirus and of such an amount of bacterin so that 1 ml of the vaccine will contain 10(9) bacteria. One part of oil adjuvant was added to five parts of the virus-bacterial blend and the blend was homogenized in the Ultraturax apparatus. The vaccine is to be used for immunization of pregnant cows and heifers; in these animals it induces the production of specific antibodies to all antigens contained in the vaccine. Its immunogenic effects were checked in 32 calves and 38 cows in the herds with the occurrence of diarrheas caused by both enteropathogenic viruses and enterotoxigenic escherichia. It was demonstrated that the inactivation did not influence in either of the viruses the process of inducing the production of specific antibodies, and the antibody response of the calves and heifers after application of 2 ml of complete inactivated vaccine was equally strong as after application of live vaccine containing only rotavirus and coronavirus. The level of the rotavirus antibodies increased on the average 30 times and 200 times, coronavirus antibodies twice and four times. The antibody response to coronavirus was negatively influenced by the relatively high levels of antibodies before vaccination. The antibody response to antigen K 99 was expressive in all cases.     

Efficacy of thiophanate and albendazole against natural infections of Dicrocoelium dentriticum, Fasciola hepatica, and gastrointestinal nematodes and cestodes in sheep

The anthelmintic efficacy of thiophanate and albendazole was compared in sheep with heavy infestations of Dicrocoelium dentriticum. The effectiveness of each drug was determined by counting the numbers of D. dentriticum in animals killed 21 days after treatment. In one group, the dose of thiophanate recommended for use against gastrointestinal (GI) nematodes (50 mg kg-1 live weight) was found to be 74.4% effective against D. dentriticum. Two tablets (each containing 76 mg of active ingredient) of albendazole per 30 kg live weight were given to a second group and the dose repeated after 1 week. Under this regime, albendazole was found to be 12.7% effective against D. dentriticum. The effect of each drug on other parasites was as follows; thiophanate had no effect against Fasciola hepatica or cestodes, while albendazole was 71.5% effective against F. hepatica and 100% effective against cestodes. Both drugs were highly effective against GI nematodes.     

Use of pathophysiological indicators for individual decision of anthelmintic treatment of ewes against gastro-intestinal nematodes in Morocco

The targeted selective treatments (TST) aim at reducing the number of anthelmintic treatments but also to maintain productivity of animals. The aim of this work was to assess the validity of pathophysiological indicators for detecting individually ewes in need for treatments in two regions of Morocco with different management and climatic environment (Chaouia plain-seven farms, and Middle-Atlas-three farms). Although resistance to benzimidazoles was already present the same drug was used for TST. The indicators tested were: FAMACHA(?) (associated with anaemia), DISCO (diarrhoea score), and BODCON (body condition score). Only FAMACHA(?) and DISCO indicators were well correlated to the EPGs. DISCO only did permit a substantial reduction (up to 85%) of the number of treatment and EPG (nematode eggs per gramme) remained low on average (less than 160).