RESUMEN
The faecal egg count reduction test (FECRT) is widely used to assess the presence or absence of levamisole resistance in gastrointestinal nematodes in sheep flocks. However, in a recent study the FECRT appeared to falsely indicate the presence of levamisole resistance. One possible explanation for this result could have been that the anthelmintic failed to completely remove all immature stages of levamisole-susceptible strains, which then developed into egg laying adults and gave misleading results in the FECRT. Artificial infection of lambs with levamisole-susceptible, benzimidazole-resistant strains of Ostertagia circumcincta, Haemonchus contortus and Trichostrongylus colubriformis was followed by treatment with levamisole when the infections were between 2 and 10 days old. Levamisole was 84%, 88% and 98% effective against these immature stages of three species, respectively. The positive control, ivermectin, was more than 99% effective against all three species. The percentage faecal egg count reduction on samples taken 11 and 20 days post-treatment with levamisole was 80% and 78%, respectively. These results demonstrate that, due to the maturation of immature stages, the FECRT based on faecal eggs counts taken 11 or more days after treatment may give results indicative of levamisole resistance despite the absence of levamisole resistant strains of gastrointestinal nematodes.
Asunto(s)
Antinematodos/uso terapéutico , Sistema Digestivo/parasitología , Resistencia a Medicamentos , Heces/parasitología , Levamisol/uso terapéutico , Infecciones por Nematodos/veterinaria , Recuento de Huevos de Parásitos/veterinaria , Enfermedades de las Ovejas , Animales , Haemonchus , Larva , Infecciones por Nematodos/prevención & control , Ostertagia , Reproducibilidad de los Resultados , Ovinos , TrichostrongylusRESUMEN
The ivermectin sustained release bolus (IVSRB), when used at turnout as recommended, will provide season-long control of parasitic bronchitis, thus obviating the need for use of a lungworm vaccine. However, some concerns have been expressed that calves treated with an IVSRB will receive so little exposure to Dictyocaulus viviparus that it will compromise their immunity in subsequent grazing seasons, which would be of particular importance in dairy herds. Although there is evidence that IVSRB-treated calves can develop immunity to D. viviparus when exposed to pasture infection, it was considered worthwhile to evaluate the compatibility of the IVSRB and lungworm vaccination to allow veterinary surgeons the option of using these products concurrently when they have particular concerns about the long term immune status of replacement dairy heifers. Thirty-two dairy replacement heifers were vaccinated with two doses of lungworm vaccine and, at turnout, half the calves received an IVSRB and the remainder an oxfendazole pulse release bolus (OPRB). At the end of the grazing season four replicate bolus treated pairs and four parasite-naive calves were challenged with 1000 D. viviparus infective larvae. At slaughter there was a 95% and 93% reduction in D. viviparus burdens in the IVSRB and OPRB treated calves respectively, compared with the unvaccinated, untreated controls. These results indicate that where it is considered necessary to use lungworm vaccination in addition to an IVSRB or an OPRB, the compatibility of these products with lungworm vaccine will allow development of a protective level of immunity to D. viviparus.
Asunto(s)
Antihelmínticos/administración & dosificación , Bencimidazoles/administración & dosificación , Enfermedades de los Bovinos , Infecciones por Dictyocaulus/prevención & control , Dictyocaulus/aislamiento & purificación , Vacunación , Animales , Antihelmínticos/uso terapéutico , Bencimidazoles/uso terapéutico , Bovinos , Preparaciones de Acción Retardada , Dictyocaulus/inmunología , Infecciones por Dictyocaulus/inmunología , Femenino , Larva , Recuento de Huevos de ParásitosRESUMEN
The interaction of the morantel sustained release bolus with the development of immunity in calves vaccinated with two doses of gamma irradiated (40 Kr) Dictyocaulus viviparus larvae was investigated under laboratory conditions. A total of 37 helminth-naive calves were used. Eight calves were used in the first part of the study to test the efficacy of a larval vaccine prepared by using gamma rays delivered from a cobalt source. In the second part of the study, four groups of four groups of four calves each were vaccinated and of these, all the animals in two groups each received a bolus. The remaining three groups (two groups of four and one group of five calves each) remained nonvaccinated with each animal in one group receiving a bolus. All the calves were challenged with approximately 2000 lungworm larvae four months postvaccination. In order to simulate possible field conditions, two of the vaccinated groups and two of the nonvaccinated groups were given a trickle infection of 800 lungworm larvae over a four-week period, three months prior to challenge. Based on a comparison of clinical signs, pathology and lungworm burdens at necropsy, the vaccination of the calves conferred a significant degree of protection (P less than 0.001) to a subsequent challenge compared with controls. The introduction of a morantel sustained release bolus and/or a trickle infection had no effect on the high degree of protection engendered by the vaccination. Nonvaccinated calves given a trickle infection, with or without a bolus, were also highly immune to challenge.
Asunto(s)
Enfermedades de los Bovinos/prevención & control , Infecciones por Dictyocaulus/prevención & control , Dictyocaulus/inmunología , Metastrongyloidea/inmunología , Morantel/administración & dosificación , Pirimidinas/administración & dosificación , Vacunas , Animales , Bovinos , Preparaciones de Acción Retardada , Interacciones Farmacológicas , Estadística como Asunto , Vacunación/veterinariaRESUMEN
Sulbactam-ampicillin is a combination of sulbactam, a beta-lactamase inhibitor, and ampicillin, a broad spectrum beta-lactam antibiotic. The efficacy of sulbactam-ampicillin was evaluated in the treatment of neonatal calf diarrhoea under conditions where a major proportion of the calves were excreting enterobacteria which were resistant to beta-lactam antibiotics. In a series of six studies with a common experimental design, three treatments (sulbactam-ampicillin, ampicillin alone and untreated control) were compared in over 300 Friesian and Ayrshire calves aged between three and 10 days and of known immunological status as determined by their zinc sulphate turbidity values. A mortality rate of 26.4 per cent in the negative control calves was reduced to 14.0 per cent with ampicillin alone and 9.5 per cent with sulbactam-ampicillin. The probability of diarrhoea subsequent to initiation of treatment was reduced from 0.50 in the negative control calves to 0.44 with ampicillin alone and 0.35 with sulbactam-ampicillin. The differences in mortality and diarrhoea observed between the calves treated with sulbactam-ampicillin and the calves in each of the other treatment groups were statistically significant. The superior efficacy of sulbactam-ampicillin is explained by the inhibitory effect of sulbactam on the beta-lactamases produced by resistant bacteria, thus rendering them susceptible to the ampicillin in the combination.
Asunto(s)
Ampicilina/uso terapéutico , Animales Recién Nacidos/microbiología , Enfermedades de los Bovinos/tratamiento farmacológico , Diarrea/veterinaria , Infecciones por Enterobacteriaceae/veterinaria , Sulbactam/uso terapéutico , Animales , Bovinos , Enfermedades de los Bovinos/microbiología , Diarrea/tratamiento farmacológico , Diarrea/microbiología , Combinación de Medicamentos , Evaluación de Medicamentos/veterinaria , Infecciones por Enterobacteriaceae/tratamiento farmacológicoRESUMEN
The clinical features of 60 pathologically confirmed cases of bovine leucosis (lymphosarcoma) are described. The majority of cases could be classified into one of four distinct clinical forms, ie, juvenile multicentric, thymic, skin and adult multicentric. Diagnosis of leucosis in animals with these forms was possible on clinical grounds alone. Five animals, four of which were adult, could not be thus classified and diagnosis required haematological and, or, pathological examinations. The clinical, epidemiological and serological findings would suggest that the cases were examples of sporadic bovine leucosis.
Asunto(s)
Enfermedades de los Bovinos/patología , Linfoma no Hodgkin/veterinaria , Animales , Bovinos , Enfermedades de los Bovinos/sangre , Enfermedades de los Bovinos/diagnóstico , Femenino , Hematócrito , Recuento de Leucocitos , Ganglios Linfáticos/patología , Linfoma no Hodgkin/sangre , Linfoma no Hodgkin/patologíaRESUMEN
A novel intraruminal bolus developed for the sustained delivery of the anthelmintic morantel tartrate was evaluated in the seasonal control of parasitic gastroenteritis in first season grazing calves. The morantel sustained release trilaminate is a trilaminate sheet consisting of a central lamina of a morantel tartrate/ethylene vinyl acetate matrix coated on both sides with a thin impermeable layer of ethylene vinyl acetate. A symmetrical pattern of circular perforations punched through the device controls the release of morantel. Administration of the trilaminate to calves significantly reduced their faecal egg output compared with untreated controls and thus reduced pasture larval contamination. Clinical parasitic gastroenteritis was prevented in the treated calves and there were significant reductions in their worm burdens compared with the untreated control calves both during and at the end of the grazing season. The control of parasitic gastroenteritis resulted in a significantly greater (P less than 0.0001) weight gain, of 45 kg, by the treated calves.
Asunto(s)
Enfermedades de los Bovinos/prevención & control , Gastroenteritis/veterinaria , Parasitosis Intestinales/veterinaria , Morantel/administración & dosificación , Pirimidinas/administración & dosificación , Tricostrongiloidiasis/veterinaria , Animales , Bovinos , Enfermedades de los Bovinos/tratamiento farmacológico , Preparaciones de Acción Retardada , Heces/parasitología , Gastroenteritis/tratamiento farmacológico , Gastroenteritis/prevención & control , Parasitosis Intestinales/tratamiento farmacológico , Parasitosis Intestinales/prevención & control , Masculino , Morantel/uso terapéutico , Recuento de Huevos de Parásitos , Factores de Tiempo , Trichostrongyloidea/efectos de los fármacos , Tricostrongiloidiasis/tratamiento farmacológico , Tricostrongiloidiasis/prevención & control , Aumento de PesoRESUMEN
On five farms identified by in vitro tests to have benzimidazole resistance, and on one farm with apparent anthelmintic failure, faecal egg count reduction tests were performed using benzimidazoles, levamisole and ivermectin. With benzimidazoles efficacy was less than 70 per cent on all farms, confirming the validity of the in vitro tests to detect benzimidazole resistance. On two farms levamisole had an efficacy of less than 90 per cent but laboratory tests failed to demonstrate levamisole resistance. Ivermectin reduced egg counts by 100 per cent on all farms.
Asunto(s)
Antihelmínticos/uso terapéutico , Heces/parasitología , Hemoncosis/veterinaria , Ostertagiasis/veterinaria , Recuento de Huevos de Parásitos/veterinaria , Enfermedades de las Ovejas/parasitología , Animales , Antihelmínticos/farmacología , Bencimidazoles/farmacología , Bencimidazoles/uso terapéutico , Resistencia a Medicamentos , Inglaterra , Hemoncosis/parasitología , Haemonchus/efectos de los fármacos , Ivermectina/farmacología , Ivermectina/uso terapéutico , Levamisol/farmacología , Levamisol/uso terapéutico , Ostertagia/efectos de los fármacos , Ostertagiasis/parasitología , Reproducibilidad de los Resultados , OvinosRESUMEN
Sulbactam-ampicillin is a combination of sulbactam, a beta-lactamase inhibitor, and ampicillin, a broad spectrum beta-lactam antibiotic. The efficacy of sulbactam-ampicillin was evaluated in the treatment of calf respiratory disease associated with ampicillin-sensitive and ampicillin-resistant strains of Pasteurella haemolytica and Pasteurella multocida. Treatment with sulbactam-ampicillin was compared with treatment with ampicillin alone in 123 Friesian calves, between three and five weeks old, exhibiting clinical signs of respiratory disease. Seven of the 59 calves treated with ampicillin died whereas only one death occurred in the 64 calves treated with sulbactam-ampicillin. In the calves which survived, treatment with sulbactam-ampicillin resulted in a significantly better clinical response, as measured by the reduction in severity of clinical signs. The results of bacteriological examinations indicated that there was a marked increase in the proportion of ampicillin-resistant isolates of P haemolytica subsequent to treatment with ampicillin, whereas the proportion of ampicillin-resistant isolates of P. haemolytica recovered from calves treated with sulbactam-ampicillin had declined. The superior efficacy of sulbactam-ampicillin observed in this study is explained by the inhibitory effect of sulbactam on beta-lactamases produced by resistant bacteria, thus rendering them susceptible to the ampicillin.
Asunto(s)
Ampicilina/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Infecciones por Pasteurella/veterinaria , Infecciones del Sistema Respiratorio/veterinaria , Sulbactam/uso terapéutico , Resistencia a la Ampicilina , Animales , Bovinos , Enfermedades de los Bovinos/microbiología , Combinación de Medicamentos , Infecciones por Pasteurella/tratamiento farmacológico , Infecciones del Sistema Respiratorio/tratamiento farmacológico , Infecciones del Sistema Respiratorio/microbiologíaRESUMEN
In order to study the prevalence of benzimidazole-resistance in equine cyathostomes, 30 stables in south east England were selected according to strict criteria but with minimum bias to provide three matched groups of 100 horses. One group was treated with fenbendazole, one with pyrantel embonate and the third was left untreated. The overall efficacies of fenbendazole and pyrantel embonate, as judged by the faecal egg-count reduction test, were 56.3 and 95.8 per cent, respectively. The numbers of horses at individual stables were too small to draw conclusions at each stable, but whereas efficacies greater than 85 per cent were recorded for pyrantel at 26 of 27 stables, the corresponding figure for fenbendazole was five of 27. Cyathostomes accounted for more than 90 per cent of the larvae cultured from faeces before and after treatment. Trichostrongylus axei was detected on 20 sites, but Strongylus species were present on only five. In the area of the survey, benzimidazole-resistance was very widespread in stables which used benzimidazole anthelmintics regularly and had more than nine horses per stable, but the benzimidazole-resistant cyathostome strains were adequately controlled with the non-benzimidazole anthelmintic pyrantel embonate.
Asunto(s)
Fenbendazol/farmacología , Pamoato de Pirantel/farmacología , Infecciones Equinas por Strongyloidea/parasitología , Strongyloidea/efectos de los fármacos , Animales , Peso Corporal , Resistencia a Medicamentos , Inglaterra , Heces/parasitología , Femenino , Fenbendazol/uso terapéutico , Caballos , Masculino , Recuento de Huevos de Parásitos/veterinaria , Pamoato de Pirantel/uso terapéutico , Infecciones Equinas por Strongyloidea/tratamiento farmacológicoRESUMEN
Danofloxacin, a novel fluoroquinolone antimicrobial drug was evaluated in the treatment of acute bacterial pneumonia in recently housed beef cattle of approximately 300 kg liveweight. The clinical responses of 67 pneumonic cattle treated with danofloxacin were compared with those of 65 cattle treated with oxytetracycline, both treatments being given by intramuscular injection for either three or five days, depending on clinical response. Both treatments resulted in a rapid fall in group mean rectal temperature and improved the clinical condition of the majority of cases. However, in comparison with oxytetracycline, danofloxacin therapy was characterised by significantly fewer treatment days, a higher response rate, significantly better reduction of pyrexia and fewer cattle requiring re-treatment.
Asunto(s)
Antiinfecciosos/uso terapéutico , Infecciones Bacterianas/veterinaria , Enfermedades de los Bovinos/tratamiento farmacológico , Fluoroquinolonas , Neumonía/veterinaria , 4-Quinolonas , Enfermedad Aguda , Animales , Infecciones Bacterianas/tratamiento farmacológico , Temperatura Corporal/efectos de los fármacos , Bovinos , Evaluación de Medicamentos/veterinaria , Fiebre/tratamiento farmacológico , Vivienda para Animales , Oxitetraciclina/uso terapéutico , Neumonía/tratamiento farmacológicoRESUMEN
Two groups of yearling suckled beef calves born between January and May of the preceding year and another two groups of lighter and slightly younger calves born between the previous March and July were grazed during their second year on four separate paddocks known to be contaminated with infective larvae of gastrointestinal nematodes. One of the heavier and one of the lighter groups were treated with a topical formulation of ivermectin three weeks and eight weeks after turnout. The treatment of the heavier group had only relatively minor parasitological effects and no effect on weight gains, whereas the treatment of the lighter cattle resulted in increased weight gains due to effective nematode control. The paper highlights that small differences in previous performances, age and exposure to parasites can have a substantial impact on the benefits accrued from anthelmintic treatment.
Asunto(s)
Enfermedades de los Bovinos/prevención & control , Parasitosis Intestinales/veterinaria , Ivermectina/uso terapéutico , Infecciones por Nematodos/veterinaria , Administración Tópica , Animales , Animales Lactantes , Anticuerpos Antihelmínticos/análisis , Peso Corporal/fisiología , Bovinos , Enfermedades de los Bovinos/parasitología , Enfermedades de los Bovinos/fisiopatología , Dictyocaulus/inmunología , Ensayo de Inmunoadsorción Enzimática/veterinaria , Heces/parasitología , Femenino , Parasitosis Intestinales/fisiopatología , Parasitosis Intestinales/prevención & control , Ivermectina/administración & dosificación , Masculino , Infecciones por Nematodos/parasitología , Infecciones por Nematodos/fisiopatología , Infecciones por Nematodos/prevención & control , Recuento de Huevos de Parásitos/veterinaria , Pepsinógenos/sangre , Distribución Aleatoria , Aumento de Peso/fisiologíaRESUMEN
Faecal samples were collected from 209 randomly selected sheep farms in southern England, and the nematode eggs extracted were tested by an egg hatch assay and by a larval development test for their resistance to benzimidazoles. Benzimidazole resistance was found on 35 per cent of farms tested in East Sussex, 44 per cent in Oxfordshire and 61 per cent in West Sussex.
Asunto(s)
Bencimidazoles/farmacología , Nematodos/efectos de los fármacos , Infecciones por Nematodos/veterinaria , Enfermedades de las Ovejas/parasitología , Animales , Resistencia a Medicamentos , Inglaterra , Heces/parasitología , Larva/efectos de los fármacos , Infecciones por Nematodos/parasitología , OvinosRESUMEN
The efficacy of danofloxacin, a novel third generation fluoroquinolone, was assessed in the treatment of pneumonia in housed calves on three farms in the FDR and Italy. Seventy three calves with clinical signs of acute pneumonia and rectal temperatures greater than 40 degrees C were treated with danofloxacin at a dose rate of 1.25 mg/kg for three or five days depending on response to treatment. The response in these calves was compared to that obtained in 77 calves treated with trimethoprim/sulpha. The clinical response achieved with danofloxacin was superior to that achieved with trimethoprim/sulpha and significantly fewer calves which received danofloxacin required five days treatment. Pasteurella haemolytica and, or P. multocida were isolated from the majority of calves prior to treatment. All isolates were sensitive to danofloxacin and over 90 percent were sensitive to trimethoprim/sulpha.