pyrantel and Swine-Diseases

Topics: Animals; Ascariasis; Clinical Trials as Topic; Female; Hepatitis, Animal; Male; Pleural Diseases; Pneumonia, Viral; Pyrantel; Swine; Swine Diseases

The results of four alternative methods of mean faecal egg count reduction percentage (FECR%) calculations were evaluated and compared using data obtained for Oesophagostomum spp. from ten sow herds. The estimates of FECR% and 95% confidence limits obtained using the four methods were different. However, there were few discrepancies in the final decision as to whether a given herd carried drug resistant isolates or not. The methods that used geometric means were more appropriate than those that used the arithmetic mean as the measure of central tendency for eggs per gram of faeces (EPG) values. The use of geometric mean EPG values in calculations has been criticized from several viewpoints, one of which is that its use reduces the comparability of reports between laboratories. If the geometric mean is to be used as we suggest in FECR% calculations, the appropriate references, number of animals in each group, minimum and maximum EPG values and the factor added to zero EPG counts should be reported in order to improve the comparability. The difficulty in obtaining groups with similar pre-treatment EPG values in field situations suggested the inclusion of pre-treatment EPG values in the calculations as an adjustment procedure. The importance of including a non-treated control group in calculations was demonstrated during this study. Therefore, we suggest the use of geometric mean EPG values, to include pre-treatment EPG values and to include the egg counts from the control group in FECR% calculations. The interpretation of the resulting FECR estimate may be different according to the purpose for which the testing procedure is carried out, e.g. survey in detecting anthelmintic resistance, control field tests, etc.

Topics: Animals; Anthelmintics; Confidence Intervals; Drug Resistance; Feces; Female; Ivermectin; Levamisole; Mebendazole; Models, Statistical; Oesophagostomiasis; Oesophagostomum; Parasite Egg Count; Piperazine; Piperazines; Pyrantel; Swine; Swine Diseases

The pharmacokinetic disposition of pyrantel after intravenous (i.v.) and oral (p.o.) administration as the citrate and p.o. administration as the pamoate salt was determined in pigs. Following i.v. administration pyrantel was quickly cleared from the bloodstream, exhibiting a terminal half-life of 1.75 +/- 0.19 h and a residence time (MRT) of 2.54 +/- 0.27 h. After p.o. administration as the citrate salt, the absorption time (MAT) of pyrantel was 2.38 +/- 0.25 h and although significant quantities of pyrantel were absorbed (mean bioavailability of 41%) the rapid clearance resulted in a MRT of only 4.92 +/- 0.36 h. By comparison, the significantly extended MAT of the less soluble pamoate salt resulted in reduced circulating concentrations and a significantly lower mean bioavailability of 16%. The poor efficacy of pyrantel citrate against nematodes inhabiting the large intestine of pigs is therefore suggested to result from insufficient quantities of drug passaging to the site of infection. When tested against pyrantel-resistant adult Oesophagostomum dentatum the mean efficacy of pyrantel citrate was only 23%, whereas the efficacy of the lesser absorbed pyrantel pamoate was 75%. These results indicate that for maximum activity pyrantel should be administered to pigs as the pamoate salt.

Topics: Administration, Oral; Animals; Antinematodal Agents; Biological Availability; Drug Resistance; Female; Half-Life; Injections, Intravenous; Kinetics; Male; Metabolic Clearance Rate; Oesophagostomiasis; Oesophagostomum; Pyrantel; Pyrantel Pamoate; Swine; Swine Diseases

Crossbred young pigs were used to test whether abbreviated infections with eggs of Ascaris suum can stimulate the acquisition of resistance to challenge. Weanling pigs from an Ascaris-free colony were kept free of A. suum until they were divided into groups at the age of 7-8 weeks. The experimental animals received pyrantel tartrate during the period when they were being exposed to increasing numbers of infective A. suum eggs and challenged 10 days after the last infective dose. Liver milk-spot counts and larval recoveries from the lungs indicated that the strongest resistance was acquired by the animals that received the drug continuously for 6 weeks while being exposed to six weekly infective egg doses. The data do not suggest any drug-related suppression of the resistance response to A. suum infection.

Topics: Animals; Ascariasis; Ascaris; Larva; Pyrantel; Pyrantel Tartrate; Swine; Swine Diseases

This study was undertaken to determine the level of resistance against pyrantel citrate in strains of Oesophagostomum quadrispinulatum and Oesophagostomum dentatum which have previously been found resistant to this anthelmintic. Groups of pigs were artificially infected with batches of infective larvae which were previously found either susceptible or resistant to pyrantel citrate. After treatment with 1, 2 and 4 times the recommended dose (14 mg kg-1) of pyrantel citrate, the resistant O. quadrispinulatum population was reduced by 51.0, 76.2 and 86.1%, and O. dentatum by 41.2, 47.9 and 78.5%. The results indicated that O. dentatum was slightly more resistant (P less than 0.05) than O. quadrispinulatum to pyrantel citrate. Treatment of the susceptible worms with 1 and 2 times the recommended dose caused a reduction in worm numbers by 61.0 and 99.4%, respectively.

Topics: Animals; Dose-Response Relationship, Drug; Drug Resistance; Female; Male; Oesophagostomiasis; Parasite Egg Count; Pyrantel; Sex Factors; Specific Pathogen-Free Organisms; Swine; Swine Diseases

An experiment was conducted with 96 weanling pigs (avg initial wt 18.5 kg) divided into six treatment with two replicates of eight pigs each. Pigs in Treatments 1, 2 and 3 were penned in outside pens with dirt lots that previously were contaminated with A. suum ova to induce a natural ascaris infection. Pigs in Treatments 4, 5 and 6 were penned in an open-front building with solid concrete floors and were experimentally infected with 2,000 embryonated A. suum. ova on d 1, 15 and 29 of the experiment. Pigs in Treatments 1 and 4 were medicated with fenbendazole (FBZ, 3 mg/[kg BW.d]) for three consecutive days during three consecutive time periods. Pigs in Treatments 2 and 5 were medicated with pyrantel tartrate (PT, 106 mg/kg feed) for 28 d. Pigs in Treatments 3 and 6 served as infected, unmedicated controls. All pigs were challenged with 100 A. suum eggs 7 d after termination of the final FBZ treatment. All pigs were killed 66 d after challenge and worms were recovered. Fenbendazole treatment resulted in greater (P less than .07) average daily gain than PT treatment in pigs penned outside. Among inside pigs, FBZ treatment resulted in better (P less than .02) feed utilization than in controls. The FBZ and PT treatments reduced (P less than .03) the total number of A. suum, the length and weight of female ascarids and the length of male ascarids compared with controls. A natural continual infection with A. suum was less effective than experimental infection in inducing protective immunity in pigs.

Topics: Animals; Ascariasis; Benzimidazoles; Female; Fenbendazole; Housing, Animal; Liver; Lung; Male; Organ Size; Parasite Egg Count; Pyrantel; Pyrantel Tartrate; Random Allocation; Swine; Swine Diseases; Weight Gain

This study was undertaken to determine whether anthelmintic-resistant Oesophagostomum spp. populations occur in Danish swine herds. A controlled field trial on selected sow herds suggested resistance to pyrantel citrate in a herd where faecal egg count depression in response to treatment was only 28.3%. This was confirmed by subsequent experimental infection of pigs where the suspected resistant Oesophagostomum isolate was compared with a susceptible worm isolate. After treatment with the recommended dose of the drug, worm burdens of the suspected isolate were only reduced by 42.6% (p greater than 0.05) in contrast to the susceptible isolate, which was reduced by 94.6% (p less than 0.01). Differential counts of the resistant isolate suggested that O. dentatum might be more resistant than O. quadrispinulatum. The resistant isolate originated from a herd, where the anthelmintic had been administered four times a year over a period of 7 years. The potential for development of anthelmintic resistance in Oesophagostomum spp. under management practices in our country is discussed in the light of the current views on predisposing factors.

Topics: Animals; Drug Resistance; Feces; Female; Housing, Animal; Male; Oesophagostomiasis; Oesophagostomum; Parasite Egg Count; Pregnancy; Pregnancy Complications, Infectious; Pyrantel; Specific Pathogen-Free Organisms; Swine; Swine Diseases

Topics: Animals; Anthelmintics; Dichlorvos; Fenbendazole; Helminthiasis; Helminthiasis, Animal; Hygromycin B; Ivermectin; Lactones; Levamisole; Piperazine; Piperazines; Pyrantel; Swine; Swine Diseases; Thiabendazole

The relative efficacies of pyrantel tartrate and of pyrantel citrate against Oesophagostomum sp in swine were evaluated in a controlled-critical study and the efficacy of pyrantel citrate in a field trial. In the controlled-critical study, pigs naturally infected with Oesophagostomum dentatum were either not treated or were treated with pyrantel citrate or pyrantel tartrate at a dosage of 510 mg of free pyrantel base/kg of feed. Six days later, the pigs were necropsied, adult O dentatum was recovered and counted, and fecal samples were examined for helminth eggs. The efficacies of pyrantel citrate and pyrantel tartrate were each 100% based on fecal egg counts and numbers of adults at necropsy. The field trial was conducted in a similar manner except that pyrantel citrate only was tested against a control group on the basis of fecal egg counts made both at the beginning and at the termination of the trial. In this study pyrantel citrate was found to reduce Oesophagostomum sp egg counts by 89.4%.

Topics: Animals; Female; Male; Oesophagostomiasis; Pyrantel; Pyrantel Tartrate; Swine; Swine Diseases

The LD50 from subcutaneous administration of levamisole in castrated male pigs (15 to 25 kg) was established as 39.8 mg/kg. Oral administration of dichlorvos (60 mg/kg, 3 times the anthelmintic dosage level) 1 hour before levamisole injection lowered blood cholinesterase activity to approximately 60% that of the controls, but did not change the LD50 of levamisole. In contrast, oral administration of pyrantel tartrate (25 mg/kg, an anthelmintic dosage level) did not lower blood cholinesterase activity, but rather, increased the toxicity by lowering the LD50 of levamisole from 39.8 mg/kg to 27.5 mg/kg. The data supported the hypothesis that levamisole toxicity was enhanced by nicotine-like compounds (ie, pyrantel), but was not affected by organophosphates (ie, dichlorvos).

Topics: Animals; Cholinesterases; Dichlorvos; Drug Interactions; Lethal Dose 50; Levamisole; Male; Pyrantel; Pyrantel Tartrate; Swine; Swine Diseases

The use of pyrantel tartrate (106 mg/kg of feed) as a continuous feed medication was evaluated in 848 finishing hogs for efficacy in preventing Ascaris suum infections, and in reducing liver fibrosis and liver condemnation at slaughter, associated with A suum infections. Liver condemnations due to Ascaris damage were reduced 100% in all pigs given pyrantel, when compared with condemnation in non-medicated controls. None of the livers from any of the medicated animals was condemned, whereas livers from 101 (21%) of 479 nonmedicated pigs were condemned due to extensive hepatic scarring. Pyrantel medication administered for 62, 45, or 28 to 31 days resulted in reductions of total number of livers lesions at slaughter by 93.4%, 80.5%, and 68.6%, respectively. In nearly all cases, hepatic lesions remaining at slaughter of pigs given pyrantel in the feed were less distinct than were lesions found on livers from nonmedicated pigs.

Topics: Animals; Ascariasis; Food Inspection; Liver; Meat; Pyrantel; Pyrantel Tartrate; Swine; Swine Diseases

A combination of pyrantel tartrate (106 mg/kg of body weight) and carbadox (55 mg/kg of body weight) in ground feed was fed to 20 weaned pigs (av wt, 14.4 kg) for 42 days. Another group of 20 pigs included nontreated controls. The pigs were farrowed and suckled in a slat-floored farrowing house and had minimal exposure to the small intestinal threadworm (Stronglyoides ransomi) until they were placed on severely contaminated dirt lots at the start of the experiment. Five pigs from each of the two groups were necropsied on day 42. Carbadox was withheld from the feed for the 15 remaining treated pigs. All other pigs were necropsied when they attained market weight, 72 to 83 days layer. Treated pigs killed at market weight had 44% fewer (P less than 0.10) kidneyworms (Stephanurus dentatus) than did control pigs. A 17% increase (P less than 0.01) in the weights of livers of control pigs when compared with treated market-weight pigs was associated with an increase of fibrotic hepatic tissue of control pigs. Worm infections were reduced in the treated market-weight pigs: by 96% (P less than 0.05) for the large roundworm (Ascaris suum), 77% (P less than 0.01) for nodular worms (Oesophagostomum spp), and 64% (P less than 0.01) for the intestinal threadworm. There was some evidence for prophylaxis in market-weight pigs (P less than 0.10) against lungworms (Metastrongylus spp), but none against the whipworm (Trichuris suis) or thick stomach worms (Ascarops strongylina and Physocephalus sexalatus). Pigs given the pyrantel tartrate in feed until attaining market weight maintained a feed-to-gain ratio superior (7.1%) to that of nontreated pigs.

Topics: Animals; Carbadox; Nematode Infections; Pyrantel; Pyrantel Tartrate; Quinoxalines; Strongylida Infections; Swine; Swine Diseases

Topics: Animals; Ascariasis; Costs and Cost Analysis; Pyrantel; Swine; Swine Diseases

Topics: Animals; Disease Models, Animal; Pyrantel; Strongyloidiasis; Swine; Swine Diseases; Thiabendazole