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1.
Dose confirmation studies of the cestocidal activity of pyrantel pamoate paste were conducted at two sites in North America during 2001. Horses with naturally-acquired cestode infections were identified by detection of typical Anoplocephala spp. eggs in feces collected between 7 and 92 days prior to treatment. Twenty and 22 horses were enrolled at Site 1 (Urbana, IL) and Site 2 (Knoxville, TN), respectively. Candidate horses were acclimated to study conditions for 14 days, ranked by length of interval since coprologic confirmation, and allocated randomly to one of two treatment groups: (T1) pyrantel pamoate paste 13.2mg pyrantel base per kilogram body weight administered orally, and (T2) untreated controls. Individual doses of pyrantel pamoate paste were prepared on the basis of contemporaneous body weights and administered to Group T1 horses on Day 0. Trained personnel monitored the animals at regular intervals after treatment to detect potential adverse reactions. Horses were euthanatized and necropsied 10-12 days after treatment. The contents of the large and small intestines were collected, and the walls of each organ were rinsed with water and inspected. Attached cestodes were recovered and preserved in 10% formalin. The intestinal contents and rinsed ingesta were washed over a #10-mesh (2mm aperture) sieve and tapeworms were extracted and preserved. Recovered cestodes were counted and examined at 1-4x magnification for identification to genus and species. At Site 1, specimens of Anoplocephala perfoliata were recovered from seven of 10 control horses, and from one of 10 horses treated with pyrantel pamoate. Mean cestode numbers were 4.52 in the control group and 0.07 for treated horses. At Site 2, cestodes were found in 10 of 11 controls (mean 26.2) and in five of 11 horses (mean 1.2) treated with pyrantel pamoate. In both studies, Group T1 means were significantly lower than the control group (P<0.005). The calculated efficacies were 98.4 and 95.5% at Sites 1 and 2, respectively. In two dose-confirmation studies, a single, oral treatment of pyrantel pamoate paste (19.13% w/w pyrantel base) at 13.2mg/kg was >or=95.5% effective against A. perfoliata in naturally-infected horses.  相似文献   

2.
Aims of this study with 13 equids naturally infected with Anoplocephala perfoliata were to document (i) a critical test with a period of 48 h from treatment to necropsy to assess the efficacy of an anthelmintic against the tapeworm, (ii) the efficacy of pyrantel pamoate oral paste at 13.2 mg pyrantel base/kg body weight, and (iii) the time after treatment when fecal egg counts would best estimate the tapeworm's prevalence in a herd. Feces passed in successive 12-h periods after treatment were examined for tapeworms. At necropsy, tapeworms in equids were identified as attached to the mucosa or unattached and, with a stereoscope, as normal or abnormal. At the time of treatment and at 6-h intervals thereafter, fecal samples were taken for egg counts. The efficacy of pyrantel pamoate was 96.6%; in 1 equid the efficacy was 75.3%, and in 8 it was 100%. "Major fragments" (worms without a scolex) accounted for 10% of the tapeworms recovered; they were not included in the efficacy analysis but should be. In 3 untreated equids necropsied, tapeworms were in the cecum, and 21.3% were detached. This protocol, when compared with a 24-h one without examination of feces, was more efficient in the treatment of trial animals and reduced underestimation and overestimation of an anthelmintic's efficacy. However, a protocol similar to this 48-h critical test but with a 24- or 36-h post-treatment period should be investigated. The mean egg count peaked 18 to 24 h after treatment and the samples taken at that time would provide the best estimate of prevelance of tapeworms in a herd. The Cornell-Wisconsin centrifugal flotation technique had a sensitivity and specificity of 100% at 18 h and 92% and 100%, respectively, at 24 h.  相似文献   

3.
The efficacy of paste and granule formulations of pyrantel pamoate against concurrent infections of Toxocara cati and Ancylostoma tubaeforme in cats was examined in a controlled trial. Three groups of 8 cats received either no medication (controls) or pyrantel pamoate in paste or granule formulations at a dosage of 20 mg/kg of body weight. After administration of the paste formulation, fecal egg counts of A tubaeforme and T cati were decreased by 98.6 and 96.4%, respectively, and 100% of hookworms and 93.5% of ascarids were removed from the intestine. After administration of the granule formulation, fecal egg counts of A tubaeforme and T cati were decreased by 99.4 and 78.2%, respectively, and 100% of adult hookworms and 88.9% of ascarids were removed. All reductions of egg counts and worm numbers were significant (P less than 0.01). The clinical safety of pyrantel pamoate was evaluated in 4- to 6-week-old kittens. Three groups of 10 kittens received either no medication (controls) or pyrantel pamoate in paste or granule formulations at the rate of 100 mg/kg for 3 consecutive days. Adverse effects were not observed in young kittens following administration of the high dose of pyrantel pamoate.  相似文献   

4.
Clinical field trials were conducted at five geographical locations in the USA (Oklahoma, Wisconsin, Tennessee, Virginia and Idaho) to evaluate the efficacy and safety of pyrantel pamoate paste (19.13%, w/w, pyrantel base) administered at the recommended dosage of 13.2 mg pyrantel base/kg (6.0 mg pyrantel base/lb) body weight (b.w.) against tapeworm infections of Anoplocephala spp. in naturally infected horses. Horses at each study site were allocated by restricted randomization based on the cestode status (positive or negative) of pre-treatment fecal egg counts to complete sets of four animals each or incomplete sets of fewer than four animals. Within sets comprising of two to four horses, one animal was randomly allocated to receive placebo vehicle paste and the remaining horse(s) received pyrantel pamoate paste administered orally at a minimum dosage of 13.2 mg pyrantel base/kg b.w. on Test Day (TD) 0. Single animal sets received pyrantel pamoate paste. Fecal samples of horses were collected and examined for equine tapeworm (Anoplocephala spp.) eggs a minimum of four times (once or thrice between TD -28 and -14, twice between TD -14 and -7, and once on TD 0) prior to treatment on TD 0. Fecal samples of horses that were positive for cestode infection pre-treatment were examined for cestode eggs on TD 7, 8, 9, 14, 15 and 16. Cestode-negative pre-treatment horses were not sampled again after treatment. A total of 241 horses (141 mares, 16 stallions and 84 geldings; 6 months-30 yrs of age; 173-646 kg; 13 recognized breeds and various crossbreds) were evaluated. The prevalence of Anoplocephala spp. determined by pre-treatment fecal examination ranged from 38.3% in Idaho to 68.1% in Tennessee with an overall prevalence of 52.3%. Ninety cestode-positive and 88 cestode-negative horses were treated with pyrantel pamoate paste, 36 cestode-positive and 27 cestode-negative horses were treated with placebo vehicle paste. Overall, 178 horses were treated with pyrantel pamoate paste, and 63 horses were treated with placebo paste. Of the 178 horses treated with pyrantel pamoate paste, no drug related, adverse clinical or neurological health events were observed. No doses of pyrantel pamoate paste were refused or lost during dosing. At each post-treatment time sampling interval, significantly fewer cestode eggs (P < 0.0115) were passed by cestode-positive horses treated with pyrantel pamoate paste compared to cestode-positive horses that received placebo paste. Efficacy of the pyrantel pamoate paste treatment ranged from 92 to 96% from TD 7 to TD 16 with an overall efficacy of 95%. The results of these trials demonstrated that pyrantel pamoate paste (19.13%, w/w, pyrantel base) administered orally at a dosage of 13.2 mg pyrantel base/kg b.w. is highly efficacious (95%) against Anoplocephala spp. and safe for use in horses with no adverse clinical or neurological health events observed under field use conditions.  相似文献   

5.
A study was initiated to determine the prevalence of tapeworms in horses in Southern Ontario and to investigate the efficacy of pyrantel pamoate, niclosamide and mebendazole. Fecal samples were taken from 580 horses of various breeds, ages and sexes in 24 locations and Anoplocephala perfoliata was found in 13.6%. This was regarded as a minimum, the true rate being probably significantly higher and the reasons for this are discussed. A brief review of the life cycle and effects of tapeworms in horses and a comparison of two flotation techniques for the diagnosis of A. perfoliata eggs in feces is given.Pyrantel pamoate, niclosamide and mebendazole were compared for efficacy in field and critical trials. In field trials, pyrantel base and niclosamide at 6.6 and 50 mg/kg respectively were found to be effective, but in critical trials their efficacy was poor, 15 and 5.6% respectively. These anthelmintics at these dose rates caused only an elimination of the terminal egg bearing segments and were without significant effect on the entire tapeworm. When pyrantel base was administered at 13.2 and 19.8 mg/kg (twice and three times the therapeutic dose rate for nematodes respectively) the efficacy was 97.8 and 100%. It would appear that pyrantel pamoate administered at 13.2 mg pyrantel base/kg is an effective therapeutic dose for tapeworms in horses. Further dose titration studies are needed for niclosamide. Mebendazole was without effect at up to four (35.2 mg/kg) times the therapeutic dose for nematodes.  相似文献   

6.
Pyrantel pamoate paste (19.13% w/w pyrantel base) for the treatment of tapeworm, Anoplocephala spp was evaluated for target animal safety and tolerance in horses treated orally at 0, 1, 3, 5, and 10 times the clinical dose of 13.2 mg pyrantel base/kg body weight administered daily for six consecutive days. Parameters evaluated included clinical signs, food and water consumption, body weights, physical examinations, clinical pathology (hematology, coagulation, serum chemistry, urinalyses, and fecal examinations), complete necropsy, organ weights, and histopathology. No adverse events or test article-related effects were observed in any treatment group during daily clinical observations of the test animals. Statistically significant changes (P < .05) lacked a dose- and/or time-dependent trend and were considered incidental. Administration of pyrantel pamoate paste did not produce any macroscopic or microscopic tissue effects in any dose group of either sex. The no-observed-effect-level (NOEL) for pyrantel pamoate paste, when administered orally to horses once daily for 6 consecutive days, was determined to be 132 mg/kg/day. Pyrantel pamoate paste (19.13% w/w pyrantel base) can be safely administered orally to horses at 13.2 mg of pyrantel base/kg for the treatment of Anoplocephala infestations.  相似文献   

7.
The purposes of this study were to evaluate pyrantel pamoate administered orally at 20 mg/kg body weight for the removal of induced or natural infections of Ancylostoma tubaeformae and Toxocara cati in cats and to compare the efficacy of paste (40 mg base/g) and granule (80 mg base/g) formulations. Thirty cats of mixed breeding and various ages with natural and/or induced infections of A. tubaeformae and T. cati were assigned to one of three treatment groups: (1) non-medicated controls; (2) paste formulation at 20 mg base/kg; or (3) granule formulation at 20 mg base/kg. Infections were induced by feeding the cats on carcasses of infected mice. The study was conducted in replicates of at least one animal per treatment per replicate. The study parameters included clinical observations, physical examinations, faecal egg counts and the numbers, species and stages of worms recovered at necropsy. The paste formulation was 99.3% and 99.7% effective in reducing egg counts of Ancylostoma sp. and Toxocara sp. respectively. The granule formulation was 97.7% and 99.9% effective in reducing faecal egg counts of Ancylostoma sp. and Toxocara sp. respectively. When administered in paste form, pyrantel pamoate was 99.5% effective in removing adult Ancylostoma and 100.0% effective against adult Toxocara. The granule formulation was 97.9% effective against Ancylostoma and 100% effective against Toxocara. No toxic effects of either formulation of the drug were noted.  相似文献   

8.
Critical tests were completed on six horses to evaluate the antiparasitic activity of a paste formulation mixture of morantel citrate and trichlorfon, administered intraorally at the dose rate of 6 mg morantel base kg-1 and trichlorfon at 30 mg kg-1. Aggregate average removals were: 78% for two horses infected with 2nd instar Gasterophilus intestinalis; 100% for one infected with 2nd instar G. nasalis; 96% for six infected with 3rd instar G. intestinalis; 100% for four infected with 3rd instar G. nasalis; 100% for five infected with Parascaris equorum; 100% for one infected with mature Oxyuris equi; 100% for five infected with Strongylus vulgaris; 72% for five infected with S. edentatus; and partial removal (25%) of Anoplocephala perfoliata infection from one infected animal. Pre- and post-treatment EPG and LPG data indicated a reduction of 97% of the mature small strongyle infections. Evidence of toxicosis was not observed in any of the horses.  相似文献   

9.
Seven critical tests in equids were conducted with single doses of fenbendazole (5 mg kg-1) alone (Panacur--American Hoechst, Somerville, NJ); (2 tests with paste and 1 with suspension formulation) or in combination with piperazine (American Hoechst); (40 mg base kg-1); (4 tests with paste formulation). The main purpose of the tests was evaluation of activity against benzimidazole-resistant small strongyles (Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus goldi, and Cylicostephanus longibursatus). Natural infections of 2 populations of benzimidazole-resistant small strongyles were evaluated; 1 was population B in 2 horses and the other was population S in 5 ponies. Removal of the 5 species of population B was 49-91% in the animal treated with fenbendazole paste alone and 100% (4 of these species present) in the animal treated with the combination. For population S, 2 of the 5 resistant species were present in small numbers in 1 animal treated with fenbendazole paste alone and all were removed; the 1 animal receiving fenbendazole suspension alone had removals of 0-70% for the 5 benzimidazole-resistant species. Also for population S, the 5 resistant species were present in 2 animals treated with the paste combination and removal was 98-100% and of 4 of the 5 resistant species in 1 animal, removal was 76-99%. Removal of large strongyles (Strongylus vulgaris and Strongylus edentatus) was 92-100% for fenbendazole paste alone or in combination with piperazine in the 5 infected animals. For Oxyuris equi, present in 1 animal treated with the combination, there was 91% removal of immature and 100% removal of mature specimens. There probHably was no activity by fenbendazole alone or the combination against bots, tapeworms, and parenteral stages of S. vulgaris and S. edentatus. The combination may have had some activity against immature Habronema spp. and mature abronema muscae.  相似文献   

10.
The efficacy of fenbendazole granules against Toxocara canis in naturally infected greyhounds housed in contaminated environments was evaluated. Eight pens, each containing three to seven greyhounds, 3-12 months of age, were randomly allotted into two treatment groups. Greyhounds in Group 1 were treated with fenbendazole granules mixed in their feed at 50 mg/kg/day for 3 consecutive days once a month for 4 months. Greyhounds in Group 2 were treated with pyrantel pamoate suspension at 5.0 mg/kg per os once a month for 4 months. Quantitative fecal examinations were performed on days 0, 10 and then on the first day of each monthly treatment. Greyhounds administered fenbendazole had fecal egg count reductions (FECRs) of 95.8 and 99.8% at 10 and 31 days following initial treatment, respectively. Greyhounds administered pyrantel pamoate had FECRs of 85.8 and 88.3% at 10 and 31 days after the first treatment, respectively. T. canis fecal egg counts conducted from Day 31 through Day 128 were significant lower in those greyhounds administered fenbendazole as compared to greyhounds administered pyrantel pamoate. Fenbendazole produced FECRs in greyhounds from Day 31 through Day 128 by 96.8-99.8%. Pyrantel pamoate reduced fecal egg counts during the same time period 71.4-98.3%.  相似文献   

11.
Aims of this study with 43 equids naturally infected with Anoplocephala perfoliata in two dose titration trials were to document (i) the usefulness of a critical test with a 48 h treatment to necropsy period, (ii) efficacy of an oral paste of 0.5-2.0 mg praziquantel/kg body weight, and (iii) when after treatment would fecal egg counts provide best estimates of the tapeworm's prevalence in a herd. All feces passed by an equid after treatment and collected in successive 12 h batches were examined for tapeworms. At necropsy, tapeworms were identified as attached to the mucosa or unattached. Tapeworms were examined with a stereoscope and identified as normal or abnormal. Fecal samples were taken for egg counts at treatment and at 6 h intervals thereafter. In 32 of 36 treated equids, efficacy was 100% and mean efficacies for 0.5, 1.0, 1.5 and 2.0 mg praziquantel/kg body weight were 85.5, 99.7, 100 and 100%, respectively. Two equids treated with 0.5 mg praziquantel/kg body weight had low efficacies (5.4 and 38.1%) and normal tapeworms were found attached in the ventral colon and in one equid also in the dorsal colon. In seven untreated equids, tapeworms were primarily in the cecum with 21.3% detached. "Major fragments" or worms without a scolex but otherwise nearly a complete worm were 20.5% of the number of intact worms; they were not included in the efficacy analysis but should be. If the two equids with low efficacy were eliminated and if the number of all tapeworms and major fragments are combined less than 0.5% were in feces within 12 h of treatment, about 20% were in the 12-24 h period, 42% in 24-36h, 24% in 36-48 h and 13.5% in the equids at necropsy. One horse passed all its tapeworms in 24 h. This 48 h test when compared with a 24 h one with no examination of feces was more efficient in use of trial animals and reduced underestimation and overestimation of efficacy. However, a protocol similar to the 48 h test but with a 24 or 36 h post-treatment period should be investigated. The mean egg count peaked 18-24 h after treatment and samples taken at that time would provide the best estimate of prevalence. The Cornell-Wisconsin centrifugal flotation technique had a specificity of 100% and at 18 and 24 h its sensitivity was 94%. A brief discussion on critical and controlled tests for assessing efficacy of an anthelmintic for A. perfoliata is presented.  相似文献   

12.
Thirty resident horses at a boarding stable in Alberta were used to evaluate the relative efficacies of ivermectin, oxibendazole, and pyrantel pamoate in reducing fecal egg output in adult horses under routine management conditions during spring and early summer, and to more clearly define the duration of suppression of fecal egg production following anthelmintic treatment. Horses were blocked according to pretreatment egg counts and randomly assigned to one of three treatments: pyrantel pamoate at 6.6 mg/kg body weight; oxibendazole at 10 mg/kg body weight; or ivermectin at 200 μg/kg body weight. All treatments were administered orally as a paste on day 0.Fecal samples were collected for examination by the modified Wisconsin procedure before treatment, and then at 4-11 day intervals up to day 72.

Very few if any strongyle eggs were found in the feces of any horses up to day 35. On days 42, 50 and 57, the geometric mean egg count for the ivermectin group was significantly (p<0.05) lower than that for the oxibendazole or pyrantel pamoate groups. Based on a survival curve analysis of the data, the mean number of days for recurrence of eggs in the feces was significantly longer for the ivermectin group than for the oxibendazole and pyrantel pamoate groups.

Under conditions encountered in this study, the posttreatment interval to resumption of fecal egg out-put in horses treated with ivermectin was eight to nine weeks, compared with five to six weeks for horses treated with oxibendazole or pyrantel pamoate.

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13.
The aims of studies in 2002 and 2003 on three farms with 76 foals naturally infected with Parascaris equorum were to (i) identify if the nematode was resistant to ivermectin and moxidectin, and (ii) confirm the effectiveness of fenbendazole and pyrantel pamoate for the parasite. Twelve clinical trials, each with a Fecal Egg Count Reduction Test, were conducted on two Thoroughbred and one Standardbred farms in southwestern Ontario, Canada. In each trial, Parascaris eggs/g feces were estimated for each foal pre- and post-treatment using the Cornell-Wisconsin double flotation and Cornell-McMaster dilution techniques. On each farm and for each trial, foals were randomized into treatment groups. Treatments were ivermectin, moxidectin, fenbendazole, pyrantel pamoate administered at the manufacturers' recommended dosages, and some foals were untreated. The overall efficacy for ivermectin was 33.5% (19 foals) and for moxidectin 47.2% (28 foals). Fenbendazole (16 foals) and pyrantel pamoate (21 foals) were highly effective for P. equorum each at 97.6%. For fenbendazole, 15 foals had 100% and for pyrantel pamoate 17 foals had >97% with 14 at 100%.  相似文献   

14.
Prevalence of anthelmintic resistant cyathostomes on horse farms   总被引：9，自引：0，他引：9  
OBJECTIVE: To determine prevalence of anthelmintic resistance in cyathostome nematodes of horses in the southern United States. DESIGN: Cross-sectional study. ANIMALS: 786 horses on 44 farms and stables in Georgia, South Carolina, Florida, Kentucky, and Louisiana. PROCEDURE: Fecal egg count (FEC) reduction tests were performed on 44 large farms and stables. Horses on each farm were treated with an oral paste formulation of fenbendazole, oxibendazole, pyrantel pamoate, or ivermectin at recommended label dosages. A mixed linear model was fitted to the percentage reduction in FEC, accounting for differences among farms, states, ages, treatments, and treatment by state interactions. RESULTS: By use of a conservative measure of resistance (< 80% reduction), the percentage of farms with anthelmintic-resistant cyathostomes was 97.7%, 0%, 53.5%, and 40.5% for fenbendazole, ivermectin, oxibendazole, and pyrantel pamoate, respectively. Mean percentage reductions in FEC for all farms were 24.8%, 99.9%, 73.8%, and 78.6% for fenbendazole, ivermectin, oxibendazole, and pyrantel pamoate, respectively. Pairwise contrasts between states for each treatment revealed that in almost all instances, there were no significant differences in results between states. CONCLUSIONS AND CLINICAL RELEVANCE: The prevalence of resistance found in this study was higher than that reported previously, suggesting that anthelmintic resistance in equine cyathostomes is becoming a major problem. Furthermore, data from these 5 southern states, which are geographically and physiographically distinct, were remarkably similar. This suggests that drug resistance in cyathostomes is highly prevalent throughout the entire southern United States and probably nationwide.  相似文献   

15.
The aim of this study with horses and a few ponies naturally infected with tapeworms was to confirm in clinical trials the efficacy and safety of a praziquantel horse paste 9%. The field trials were conducted in 1997 and 1998 in Canada, France, Germany and New Zealand. A secondary aim of the study in Canada was to determine if a 24h post-treatment fecal sample provides the best estimate of the prevalence of tapeworms in horses when using a fecal examination technique. Fecal samples were taken from each of 1062 animals at least three times pre-treatment (PRT). In Canada, fecal samples were examined using the Cornell-Wisconsin centrifugal flotation technique, and in France, Germany and New Zealand using a centrifugation/flotation technique. In each trial, the animals were randomized into two treatment groups: praziquantel horse paste 9% at 1mg/kg body weight (BW) and untreated. Fecal samples were taken from each animal nine times post-treatment and over a period of 5 weeks. In Canada, a fecal sample was taken also at 24h after treatment. Personnel examining the samples were "blinded" to treatment groups. On the day of treatment, each treated animal was examined for adverse reactions to the paste 10min after treatment and then hourly for 4h. Thereafter, each animal was examined once daily for 5 weeks. In Canada, Germany and New Zealand, the only tapeworm egg found was Anoplocephala perfoliata. In France, A. perfoliata was the most common species and a few animals had A. magna and Paranoplocephala mamillana. The prevalence of A. perfoliata among animals sampled in Canada, France, Germany and New Zealand was 51.8, 34.4, 13.1 and 26.2%, respectively. A total of 248 animals were treated with the praziquantel paste and all except one accepted it readily. There were 292 animals completing the study, 219 treated and 73 untreated. In Canada, Germany and New Zealand, the efficacy of the praziquantel horse paste 9% against A. perfoliata was 100%. In France, the efficacy against A. perfoliata, A. magna and P. mamillana was 90.9, 100 and 100%, respectively. The best estimate of prevalence for A. perfoliata in a herd was derived from fecal samples taken 24h after treatment. At 24h, 22 of 23 treated horses were positive, whereas on any day pre-treatment fewer horses were positive. Adverse reactions observed were mild to moderate colic and in only two treated horses.  相似文献   

16.
Pyrantel pamoate, formulated in a beef-based chewable tablet, was evaluated for efficacy in dogs against induced and natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Dose titration trials were conducted in Canada, the UK and Germany in dogs treated with pyrantel (as pamoate salt) at 0, 2.5, 5 or 10 mg kg-1 body weight. These studies showed that a dose rate of 2.5 mg kg-1, the efficacy of pyrantel against adult T. canis, T. leonina, U. stenocephala and A. caninum was 76.1, 85.6, 100 and 87.9%, respectively. Efficacy at 5 mg kg-1 against the same parasites was 94.2, 92.0, 93.5 and 93.8%, respectively, and at 10 mg kg-1 efficacy was 91.2, 97.6, 98.7 and 91.3%, respectively. No adverse effects due to treatment were seen in any of these trials.  相似文献   

17.
Trials were conducted in ponies to evaluate the efficacy of pyrantel pamoate (Strongid-T®) and two newer anthelmintics not yet commercially available, nitramisole and avermectin B1a, against migrating Strongylus vulgaris larvae. Ponies were removed from their mares within 24-48 hr after birth and reared in isolation, worm free. Between six and 14 weeks of age they were infected with 2000 or 2500 infective S. vulgaris larvae. Subsequently, they were monitored daily for clinical signs until the experiment terminated at 28 days postinfection. All ponies showed increased body temperature and reduced appetite within the first week of infection. All anthelmintics were administered on day 7 and in addition pyrantel pamoate was given on day 8 postinfection. The anthelmintics were in liquid formulation. Nitramisole and pyrantel pamoate were given by stomach tube and avermectin B1a by subcutaneous injection.

Following administration of these compounds toxic reactions were not observed. All anthelmintics caused a reduction in body temperature and increased appetite and effected a clinical cure. In ponies which were not treated with an anthelmintic, temperatures remained elevated and appetites never returned completely to normal. These ponies also showed variable degrees of lethargy, depression, recumbency and colic and the majority died between two and three weeks postinfection. At necropsy, these control ponies showed variable degrees of adhesions involving the abdominal organs, necrosis of the ileum and cecum and severe arteritis and thrombosis of the major abdominal arteries and their branches.

Although pyrantel pamoate, used at eight times the therapeutic dose for intestinal nematodes in the horse, effected a clinical cure it did not produce a radical cure. At necropsy, ponies treated with pyrantel pamoate had arteritis and thrombosis of the cranial mesenteric artery and its major branches. Nitramisole and avermectin B1a were able to effect both a clinical and radical cure.

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18.
The efficacy of ivermectin, fenbendazole, pyrantel pamoate and doramectin was evaluated under field conditions at 2 sites in the Free State Province of South Africa. The study involved 25 horses at each site, divided into 5 groups of equal size. Ivermectin, fenbendazole and pyrantel pamoate were administered orally at doses of 0.2, 10 and 19 mg/kg respectively. Doramectin was administered by intramuscular injection at a dose of 0.2 mg/kg. Treatment efficacy was based on the mean faecal egg count reduction 14 days post treatment. At site A a faecal egg count reduction of 100% was found after treatment with ivermectin, fenbendazole and doramectin. A 96.1% reduction was found after treatment with pyrantel pamoate. At site B ivermectin and doramectin produced a 100% reduction in faecal egg counts, fenbendazole produced an 80.8% reduction and pyrantel pamoate a 94.1% reduction. Doramectin produced a 100% reduction in faecal egg counts at both sites, despite not being registered for use in horses. In addition, the results indicated reduced efficacy of fenbendazole at site B, which suggested benzimidazole resistance. Larval cultures showed that cyathostomes accounted for between 86 and 96% of pre-treatment parasite burdens at both sites. Other helminths identified in the faecal samples were Strongylus spp. and Trichostrongylus axei.  相似文献   

19.
Anthelmintic products form the basis of helminth control practices on horse stud farms at present. Regular evaluation of the efficacy of these products is advisable, as it will provide information on the worm egg reappearance period and the resistance status in the worm population. The aim of this study was to evaluate the efficacy of doramectin, pyrantel pamoate, ivermectin and moxidectin on a Thoroughbred stud farm in the Western Cape Province, South Africa. The study also compared the anthelmintic efficacy of two moxidectin formulations administered at their recommended dosages (an injectable, at 0.2 mg/kg, not registered for horses, and an oral gel at 0.4 mg/kg, registered for horses). Two mixed-sex groups of 30 yearlings and 40 weaners were tested in 2001 and 2002, respectively, divided into 3 and 4 groups of equal size. In 2001, moxidectin was one of 3 drugs administered orally and at a dose rate of 0.4 mg/kg. In 2002, pyrantel pamoate and ivermectin were orally administered at 19 and 0.2 mg/kg. Moxidectin and doramectin (the latter not registered for horses) were administered by intramuscular injection at a dose of 0.2 mg/kg, the dosage registered for other host species. The faecal egg count reduction test was used to determine the anthelmintic efficacies in both years. Each animal acted as its own control and the arithmetic mean faecal egg count and lower 95% confidence limit was calculated for each of the groups. A 100% reduction in the faecal egg counts and a 100% lower 95% confidence limit was recorded for moxidectin (0.4 mg/kg) in 2001. In 2002, a 99% and 96% reduction was recorded for pyrantel pamoate and ivermectin, respectively. In the same year doramectin and moxidectin (both injectable and given at 0.2 mg/kg) did not have any effect on worm egg counts. Of the 4 drugs tested in 2002, only pyrantel pamoate recorded lower 95% confidence limits above 90%.  相似文献   

20.
By collecting fecal samples every 2 weeks beginning at 2 months of age, 32 foals from a single Texas farm were monitored. The foals were administered ivermectin paste at the time of the first collection and again monthly. When foals had Parascaris egg counts higher 2 weeks after ivermectin treatment than at treatment, they were administered pyrantel pamoate at the manufacturer's recommended dose (6.6 mg/kg) or at twice the recommended dose (13.2 mg/ kg) when tapeworm eggs were also detected. An elevation or only minimal reduction (less than 75%) in Parascaris egg counts was seen 2 weeks after ivermectin treatment until the foals were 8 months of age, at which time there was an 85% reduction in fecal egg count after treatment. When pyrantel was administered at the manufacturer's recommended dose, a 42% to 84% reduction in egg counts occurred, but at 13.2 mg/kg there was a 98% to 100% reduction in fecal egg counts 2 weeks posttreatment. However, pyrantel failed to control strongylate egg counts even at the elevated dose, whereas ivermectin reduced strongylate fecal egg counts by greater than 99%, determined 2 weeks posttreatment. Pyrantel, but not ivermectin, lowered Parascaris egg counts. Ivermectin, but not pyrantel, lowered strongyle egg counts 2 weeks post administration. A single drug for all ages of horses approach to parasite control requires rethinking. Combinations of drugs or more careful evaluation of anthelmintics in foals may be necessary for continued parasite control.  相似文献   

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