Efficacy of diclazuril in the control of intestinal coccidiosis in rabbits.

The anticoccidial efficacy of diclazuril was studied in rabbits artificially infected with Eimeria flavescens, Eimeria intestinalis, Eimeria magna and Eimeria perforans. Continuous administration at 1 and 2 ppm in pelleted feed proved to be highly efficacious in controlling oocyst output and faecal scores. The weight gain was comparable and the feed efficiency slightly improved compared with the non-infected, non-medicated controls, and clinical signs were fully prevented. Medication of rabbits at 0.5 ppm also provided a significant improvement in all parameters compared with the infected, non-medicated controls. In order to obtain 100% effectiveness in the control of intestinal coccidiosis in rabbits, continuous medication at 1 ppm is recommended.

Efficacy of levamisole pour-on compared with levamisole subcutaneous injection against Dictyocaulus viviparus infection in calves.

The efficacy of levamisole pour-on against Dictyocaulus viviparus was compared to that of subcutaneous levamisole injection. Eighteen calves were raised individually and artifically infected with D. viviparus larvae. Faecal samples were collected 27 and 28 days later and larvae per gram (l.p.g.) determined. The animals were then divided into three comparable groups. Group 1 animals remained untreated as controls. Group 2 animals received levamisole 10% w/v subcutaneous injection at a dose of 5 mg kg-1 and Group 3 received levamisole pour-on 20% w/v at a rate of 10 mg kg-1 applied transdermally. Results of l.p.g. measurements from faecal samples taken 7 and 8 days post-treatment indicated a dramatic reduction in the worm burden of animals in both treatment groups. Necropsies at 14 days post-treatment revealed few adult worms in these groups, indicating a 99 and 98% kill rate for pouron and subcutaneous injection, respectively.

Helminth and protozoan parasites in dogs and cats in Belgium.

This study investigates the level of helminthic and protozoal infestation over the last 10 years in strays, well-cared-for dogs and cats. Determination of the prevalence of infections was based either on faecal examination or on worm counts at necropsy. Of 2324 faecal flotations (NaCl sp.gr. 1.20) of stray dogs, 34.2% had eggs or proglottids of one or more worm species consisting of Toxocara canis (17.4%), Toxascaris leonina (10.1%), Uncinaria stenocephala (11.4%), Trichuris vulpis (7.0%) and cestodes (2.1%). Isospora oocysts were observed in 5.2% of the dogs. The data on the distribution of the various worm species in the positive dogs indicate that T. canis eggs were by far the most common (50.9%). Necropsy data from 212 infected dogs indicate that 38.9% were infected with T. canis and 33.7% with T. leonina. The overall prevalence of worm infestation of 246 well-cared-for kennel dogs, based on worm egg counts by the McMaster technique, was 36.1%. Of 30 feline faecal samples examined by flotation, 83.3% were positive for parasites, including Toxocara cati (60%), Ancylostoma tubaeformae (36.6%), Taenia (Hydatigera) taeniaeformis (20%) and coccidia (30%). Toxocara cati was the most frequently found worm species at the necropsy of 25 cats (52%). Toxoplasma was not observed.

Efficacy of diclazuril in the prevention and cure of intestinal and hepatic coccidiosis in rabbits.

The efficacy of diclazuril against intestinal and hepatic coccidiosis was studied in artificially infected rabbits. Prophylaxis against intestinal coccidiosis was evaluated using a mixed infection of Eimeria intestinalis, Eimeria magna and Eimeria perforans. Continuous medication in the feed at 1 p.p.m. was 100% effective in reducing oocyst output and faecal scores, and weight gain and feed efficiency were normal. Hepatic coccidiosis induced by Eimeria stiedai was prevented at 0.5 and 1 p.p.m. as shown by negative oocyst counts, normal liver weight, absence of liver lesions, and normal body-weight gain and feed efficiency. Medication at 1 p.p.m. for 7 consecutive days during the prepatent phase of hepatic coccidiosis resulted in large reductions in oocyst counts and lesion scores with a normal liver weight and growth performance. Diclazuril at 1 p.p.m. in the feed prevented both intestinal and hepatic coccidiosis in rabbits and can be advocated for safe mass medication.

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of anthelmintics for dogs and cats.

Guidelines have been designed to assist in the planning, operation and interpretation of studies for the assessment of the efficacy of drugs against helminth parasites of dogs and cats. The advantages, disadvantages and application of critical and controlled tests are presented. Information is also provided on the selection of animals, housing, feeding, dose-titration, confirmatory and clinical trials, record keeping and necropsy procedures. These guidelines should assist both investigators and registration authorities involved in the evaluation of anthelmintics to employ comparable and standard procedures and will have the added benefit of minimising the numbers of animals needed for such tests.

Anthelmintic activity of flubendazole in naturally infected geese and the economic importance of deworming.

The efficacy of flubendazole food medication against roundworms in geese was determined under controlled field conditions. The geese were infected with Amidostomum anseris, Capillaria anseris, Trichostrongylus tennis, and Syngamus trachea. Medicated food was given for 7 consecutive days at a level of 30 ppm. Anthelmintic activity, egg production, and hatchability were recorded. Flubendazole medication resulted in a 100% worm elimination, no consistent change in egg-lay performance, and a highly significant increase in hatchability.

Efficacy of diclazuril against Eimeria dispersa in turkeys.

Diclazuril, a new anticoccidial drug, was tested for its efficacy against Eimeria dispersa in turkeys. A dose-titration study indicated that diclazuril at dosages of 0.5, 1, and 2 ppm in the feed was highly effective in terms of weight gain and suppression of lesions, abnormal droppings, and oocyst shedding.

Efficacy of diclazuril against turkey coccidiosis in a floor-pen experiment.

Diclazuril, a new anticoccidial drug, was tested for its efficacy in turkeys against mixed Eimeria infections. A floor-pen trial indicated that diclazuril at dosages of 0.5 ppm and 1 ppm in the feed was highly effective against the major pathogenic species E. adenoeides, E. gallopavonis, and E. meleagrimitis in suppressing intestinal and cecal lesions and oocyst shedding. Weight gain and feed conversion improved, particularly at 1 ppm.

Efficacy of diclazuril against turkey coccidiosis in dose-titration studies.

Diclazuril, a new anticoccidial drug, was tested for its efficacy in turkeys against single Eimeria infections. Dose-titration studies indicated that diclazuril at dosages of 0.1, 0.5, 1, and 2 ppm was highly effective against the major pathogenic species-E. adenoeides, E. gallopavonis, and E. meleagrimitis-in terms of weight gain and suppression of lesions, abnormal droppings, and oocyst shedding.

In vivo action of the anticoccidial diclazuril (Clinacox) on the developmental stages of Eimeria tenella: a histological study.

Diclazuril, a new benzeneacetonitrile anticoccidial, has potent activity against various stages of Eimeria tenella. A single treatment of experimentally infected chickens during the prepatent phase (up to day 5) results in a complete interruption of the life cycle and oocyst shedding. The first- and second-generation schizonts show extensive degenerative changes that finally result in a complete loss of the parasitic stage. The degeneration is characterized by loss of internal structure, the appearance of many intracytoplasmic vacuoles, and incomplete merogony. The merozoites themselves show similar degenerative changes, including the presence of numerous small vacuoles in the cytoplasm. Diclazuril is also effective against both the micro- and macrogametocytes that have a ballooned appearance and loose their internal structure completely. In the macrogametocytes, wall-forming bodies either do not develop or disappear rapidly. Development of typical caecal lesions is prevented when treatment with diclazuril is initiated before large numbers of second-generation schizonts appear, i.e., day 3. It is concluded that diclazuril is lethal against both the asexual and the sexual stages of E. tenella. At the proposed use level of 1 ppm in the feed, the life cycle is interrupted at a very early stage and lesion development and oocyst shedding are completely prevented.

Scanning electron microscopic observations of Cysticercus fasciolaris (=Taenia taeniaeformis) after treatment of mice with mebendazole.

The time-related topographical changes in mature cysticerci of Taenia taeniaformis induced after medication of infected mice with 250 ppm of mebendazole are described. The changes included the gradual disappearance of microtriches and progressive degeneration of the tegment resulting in an irregular surface with grooves, holes, and craterlike structures. Host cells adhered to the altered areas and the number of these cells increased when more severe changes became apparent. Finally the necrotized cysticerci, which lost their tegument completely, were almost entirely covered with adhesive host cells. A difference in the time sequence of the reported changes occurred between the scolex, the pseudoproglottids, and the bladder. This difference in susceptibility towards the drug between the three parts of the parasite in relation to the morphology of their microtrichous covering is discussed.

Morphological changes in cysticerci of Taenia taeniaeformis after mebendazole treatment.

The progressive micromorphological changes in Taenia taeniaeformis cysticerci, induced by a single parenteral treatment of the infected mice with mebendazole, are described. The time-related alterations concerned the tegument and tegumental cells and were successively: disappearance of microtubules, accumulation of secretory substances in the Golgi areas, decrease in number to complete loss of microtriches, "ballooning" of all tegumental cells with subsequent burst, vacuolization and degeneration of the tegument, and finally necrosis of the pseudoproglottids. Similar but less pronounced injuries were seen in the scolices, although microtubules disappeared as early as in the pseudoproglottids. Microtubules from the host tissues remained intact. The meaning of the apparent primary interference of mebendazole with the microtubular system in relation to the subsequently observed death of the cysticercoids is discussed.

In vivo action of the anticoccidial diclazuril (Clinacox) on the developmental stages of Eimeria tenella: an ultrastructural evaluation.

A single 5-mg/kg oral dose of diclazuril affected both the asexual and sexual development of Eimeria tenella in experimentally inoculated chickens. In second-generation schizonts, early growth and nuclear divisions progressed normally, but a marked inhibition of merozoite formation was observed. Exogenesis of merozoites was largely prevented, whereas production of micronemes, amylopectin granules, and dense bodies and the formation of rhoptries, conoid, and pellicle continued. All these subcellular organelles accumulated, together with differentiated nuclei, within the main cytoplasmic mass. In the end, complete necrosis of the schizonts occurred. In macrogamonts, dilation of the rough endoplasmic reticulum around type II wall-forming bodies, fusion of type II wall-forming body contents, disturbance of the normal parallel arrangement of rough endoplasmic reticulum, and disruption of row formation of amylopectin granules became evident. In the microgamonts, normal evagination of microgametes was prevented; the flagellar complex formed within the main cytoplasmic mass and the differentiated nuclei remained present within the parasite body. The macro- and microgamonts also ended up in a stage of complete necrosis. These data indicate that diclazuril treatment primarily affects the normal differentiation of the respective endogenous stages during parasite development. This leads to complete degeneration of schizonts and gamonts indicating the lethal effect of this new anticoccidial compound.

Flukicidal action of closantel against immature and mature Fasciola hepatica in experimentally infected rats and sheep.

The relative importance of peak level- and residual level-related flukicidal activity of closantel against immature and mature Fasciola hepatica was evaluated in a comparative efficacy trial using two animal species with a different plasma elimination pattern, that is, the rat and the sheep with an elimination half-life of less than one week and of two to three weeks, respectively. The rats were dosed orally with closantel at 20 mg kg-1 at two, four, six, eight and 10 weeks; the sheep at 10 mg kg-1 at eight, 10 and 12 weeks after artificial infection. Necropsy was performed either one week after treatment or 12 weeks after infection. Efficacy rates and the length of the recovered flukes were evaluated. It was demonstrated that the flukicidal effect of closantel is directly related to its peak plasma levels and less to its residual plasma concentrations. In the rat, a high efficacy (P less than 0.001) could be demonstrated against immature stages of four weeks or older. The two-week immature stages were less markedly affected. No significant differences in efficacy and size of the flukes were noted between the animals autopsied one week after treatment and those autopsied 12 weeks after infection. In the sheep, the efficacy against six-week and eight-week-old immature stages varied between 70.3 and 76.8 per cent and between 92.8 and 96.5 per cent, respectively. As in the rats, no marked differences in efficacy were noted between the animals autopsied one week after treatment and those autopsied 12 weeks after infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Action of the anticoccidial clazuril on the endogenous stages of Eimeria labbeana and E columbarum in experimentally infected pigeons.

Racing pigeons were artificially infected with a mixed inoculum of Eimeria labbeana (85 per cent) and E columbarum (15 per cent) and treated orally with 2.5 mg clazuril either on day 1, 2, 3, 4, 5, 6 or 7 after infection. The impact of the treatment on the different developmental stages was evaluated by oocyst output and by histological examination of the duodenum and jejunum. The life cycle always became completely interrupted, but maximal effects were noted when treatment was given on day 4, 5 or 6 after infection. Treatment during patency completely interrupted oocyst excretion within three days after dosing. Degenerative changes in schizonts and gametocytes were always observed. The histology revealed a reduced number and abnormal structure of developing merozoites; a ballooned aspect and presence of numerous small vacuoles in the microgametocytes; the absence of typical wall-forming bodies in macrogametocytes and a complete absence of oocysts. It is concluded that clazuril has a coccidiocidal effect on the asexual and sexual developmental stages of both Eimeria species, resulting in a complete interruption of the life cycle.

Anthelmintic efficacy of flubendazole paste against nematodes and cestodes in dogs and cats.

Small dogs and cats, naturally infected with nematodes and cestodes, were used in a critical test under laboratory conditions to determine the palatability and efficacy of flubendazole as a past formulation. Subsequently, a control test in dogs was conducted under field conditions. A 4.4% past formulation was given at a dosage of 22 mg/kg of body weight once a day for 2 or 3 consecutive days. In a critical test in dogs, the efficacy against Toxocara canis was 97.4% after a 2-day administration and 100% after 3 days. Toxascaris leonina seemed to be the most susceptible worm species, since either 2 or 3 treatments were 100% active. The efficacy against Uncinaria stenocephala was 97.5% after 2 treatments; the same dose level for 3 days improved the efficacy to 100%. The efficacy was 100% for the removal of Trichuris vulpis after a daily dosage for 2 days and 96.7% after 3 days. One of 2 dogs infected with Taenia pisiformis was cleared of the infection after a 2-day treatment, and 3 of 4 dogs were cleared after a 3-day regimen. All cats were cleared of Toxocara cati after 2 or 3 days of treatment. One of 2 cats infected with Hydatigera taeniaeformis was cleared of the infection after a 2-day treatment; a 3-day treatment in 7 cats was 100% effective. The results in the laboratory test in dogs were confirmed under field conditions by a control test, based on the reduction of eggs per gram of feces count after treatment. The paste formulation was well accepted by all dogs and cats without any side effects.

Diclazuril, a new broad spectrum anticoccidial drug in chickens. 1. Dose titration studies and pilot floor pen trials.

Diclazuril, a new anticoccidial drug, was tested in poultry against six Eimeria species either in single species infections in dose titration studies or in mixed species infections in floor pen trials. The dose titration studies in cockerels indicated that diclazuril at dosages of 10, 5, 1, and .5 ppm was highly active against all major pathogenic species: E. tenella, E. acervulina, E. necatrix, E. brunetti, E. maxima, and E. mitis and effective in terms of weight gain and suppression of mortality, dropping scores, and oocyst counts. In two floor pen trials diclazuril was fed for 6 wk to broiler chickens experimentally infected either with E. tenella and E. acervulina or with E. necatrix and E. brunetti. Dose levels of 10, 5, and 1 ppm suppressed mortality and lesion scores. Even at 1 ppm the mean terminal body weight, feed conversion, and productivity index of treated birds were comparable to results for the uninfected, unmediated controls. In these pilot studies, involving 1,020 Hisex and 1,000 Hubbard broiler chickens, it has been demonstrated that diclazuril at the dose level of 1 ppm in the diet is an excellent anticoccidial without any adverse effects.

Effect of diclazuril (Clinacox) on the development of protective immunity against Eimeria tenella: laboratory trial in broiler chickens.

The effect of diclazuril, fed to chickens at 1 ppm in the feed, was studied to determine whether the drug interfered with the development of immunity to Eimeria tenella. Group A was not treated, Groups B and C received diclazuril from Day 1 until Day 15, after which time the medicated feed was replaced by blank feed for the remainder of the experiment from Day 16 until Day 42. Immunization was performed in Groups A and B by artificial trickle infections with 2,000 sporulated oocysts per bird on Days 4, 6, 8, 11, and 13. On Day 29, a challenge infection was given using 200,000 oocysts per bird. The unmedicated birds (Group A) developed subclinical coccidiosis after the trickle infections with excretion of oocysts and a slightly decreased growth performance. At challenge, a good protective unimmunity was present, reflected by a good growth performance and a low oocyst excretion. The unimmunized birds (Group C) developed a severe clinical disease after challenge with high oocyst output, increased mortality, and poor growth performance. The diclazuril-medicated, trickle-infected birds (Group B) were well protected, both against the immunizing trickle infections and the challenge infection. After challenge, no clinical disease developed, although some lesions and oocyst excretion were present. It is concluded that, under the conditions of the trial, diclazuril did not significantly interfere with protective immunity formation against E. tenella.

Diclazuril, a new broad spectrum anticoccidial drug in chickens. 2. Battery trials.

Battery trials have confirmed the broad spectrum anticoccidial activity of diclazuril as previously reported in dose titration studies. The advocated dose level of 1 ppm in the diet demonstrated excellent activity against the economically most important Eimeria species. At this dose level, body weight gains were comparable to those of uninfected, unmedicated controls and the oocyst production was negative in most species. Lesion scores and dropping scores were nil or highly reduced. An E. maxima-147 strain, less sensitive to ionophores, also responded well to diclazuril. It was concluded that diclazuril is a promising anticoccidial for the control of all species of coccidia that cause losses to the poultry industry.

Diclazuril, a new broad-spectrum anticoccidial for chickens. 3. Floor-pen trials.

Diclazuril is a benzeneacetonitrile showing great promise as a broad-spectrum anticoccidial agent for chickens, turkeys, and rabbits. The high anticoccidial activity of diclazuril in chickens, as first reported in dose-titration studies and battery trials, was confirmed in three floor-pen trials. The efficacy was demonstrated against six major pathogenic species of Eimeria after artificial infection with one or more species. The experimental data indicated that diclazuril, at dose levels of .5, .75, 1, and 2 ppm, had a high anticoccidial activity in terms of preventing mortality, suppressing or reducing lesion scores, and allowing for normal weight gains as well as productivity. The performances obtained with diclazuril was generally comparable with that of salinomycin at 60 ppm and that of lasalocid at 90 ppm.