Comparative persistent efficacy of doramectin, ivermectin and fenbendazole against natural nematode infections in cattle

doi:10.1016/S0304-4017(97)00076-9

Veterinary Parasitology

Volume 72, Issue 1, September 1997, Pages 33-41

https://doi.org/10.1016/S0304-4017(97)00076-9 Get rights and content

Abstract

A study was conducted in Argentina, to investigate the period of protection of a single injection of doramectin administered subcutaneously (SC) at 200 μg kg⁻¹ (1 ml/50 kg) compared with single treatments of ivermectin (200 μg kg⁻¹ SC) and fenbendazole (5 mg kg⁻¹ PO), against field infections of gastrointestinal parasites of cattle. Eighty-three animals were selected and ranked on the basis of serial fecal egg counts (e.p.g.'s). From this group, three animals were slaughtered before treatment and their lungs, abomasum, small and large intestines, were processed for parasite counts and identification. The remaining 80 animals were allocated in ranked groups of four to a control or one of three treated groups. Animals of the four groups were grazed together in the same pasture for the duration of the study. Treatments were administered on Day 0. Individual fecal samples were collected at weekly intervals for the first 49 days post-treatment and twice a week from Day 52 to Day 84 (end of study). At each collection day fecal samples were pooled for coprocultures. On Day 28 and 56, two animals from each group, previously identified on Day 0, were killed and their parasite burdens determined. The duration of protection of a single injection of doramectin was longer than ivermectin or fenbendazole treatment. On Day 56, the total number of parasites found in doramectin-treated animals was significantly (P < 0.05) lower than parasite burdens found in either ivermectin- or fenbendazole-treated animals. The longer persistent activity of doramectin was expressed by the lower number of adults and L₄ stages of Ostertagia ostertagi. Data from this experiment demonstrated the limitations of using fecal egg counts to evaluate the persistent efficacy of anthelmintics. The duration of activity of doramectin was demonstrated more accurately by parasite counts in cattle from each group since decreasing e.p.g.'s were seen in non-medicated animals without changes in total parasite burdens.

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Anthelmintic resistance in cattle: A systematic review and meta-analysis
2018, Livestock Science
A systematic review and meta-analysis was conducted to identify, evaluate, and synthesize primary literature reporting the efficacy of anthelmintic drugs in cattle. Information on the bibliographic data, anthelmintic drugs, animals, reduction method, days after application, parasite genera, type of application, and dosage were collected. The final data base was composed of 70 articles published between 1986 and 2016 with a total of 8,976 animals. The mode of application interfered with the efficacy of anthelmintic drugs in cattle (P < 0.05); oral application was superior to injectable and pour-on drugs. The combined use of drugs was superior to single macrocyclic lactones including ivermectin (P < 0.05), in this way the combined use was more effective than the single use of drugs for the control of gastro-intestinal nematodes in cattle (P < 0.05). Nematode genera in the abomasum (Ostertagia spp., Haemonchus spp.) and intestine (Cooperia spp.) were evaluated. Levamisole had a greater efficacy for Cooperia spp. than Ostertagia spp. (P < 0.05); ivermectin had a greater efficacy for Ostertagia spp. than Haemonchus spp. (P < 0.05); doramectin had a greater efficacy for Ostertagia spp. than Cooperia spp. (P < 0.05). Dosing in larger quantities and according to the manufacturer's recommendation was most efficient, and the dose limiting species differed between substance classes. The test based on the count of eggs per gram of faeces indicated a reduced efficacy of the drug as days passed following treatment. The forest plot did not show a difference (P > 0.05) between interventions (resistance and efficacy). The results of this systematic review and meta-analysis suggest that anthelmintic resistance in cattle is present on several continents. Therefore, there is a need to replace the schemes based on the exclusive use of drugs in order to decrease the selection pressure.
Modelling the consequences of targeted selective treatment strategies on performance and emergence of anthelmintic resistance amongst grazing calves
2016, International Journal for Parasitology: Drugs and Drug Resistance
Citation Excerpt :
For example, the genotype combination S1S1 R2R2 would be considered to have the same phenotype as S1R1S2 R2. Additionally it has been observed that the efficacy of ivermectin is not the same across all stages of development (Eddi et al., 1997; Vercruysse et al., 2000; Yazwinski et al., 2009), hence the efficacy for each stage was defined according to Yazwinski et al. (2009). Parameters were fitted to published literature to show the expected persistence activity of ivermectin against O. ostertagi parasites (Armour et al., 1985; Borgsteede and Hendriks, 1986; Williams and Broussard, 1995; Toutain et al., 1997; Ranjan et al., 1997); as such, w1 = 7.3, w2 = 0.47 and wX was dependent on the drug efficacy which was defined separately for each genotype according to the number of R alleles present.
The development of anthelmintic resistance by helminths can be slowed by maintaining refugia on pasture or in untreated hosts. Targeted selective treatments (TST) may achieve this through the treatment only of individuals that would benefit most from anthelmintic, according to certain criteria. However TST consequences on cattle are uncertain, mainly due to difficulties of comparison between alternative strategies. We developed a mathematical model to compare: 1) the most ‘beneficial’ indicator for treatment selection and 2) the method of selection of calves exposed to Ostertagia ostertagi, i.e. treating a fixed percentage of the population with the lowest (or highest) indicator values versus treating individuals who exceed (or are below) a given indicator threshold. The indicators evaluated were average daily gain (ADG), faecal egg counts (FEC), plasma pepsinogen, combined FEC and plasma pepsinogen, versus random selection of individuals. Treatment success was assessed in terms of benefit per R (BPR), the ratio of average benefit in weight gain to change in frequency of resistance alleles R (relative to an untreated population). The optimal indicator in terms of BPR for fixed percentages of calves treated was plasma pepsinogen and the worst ADG; in the latter case treatment was applied to some individuals who were not in need of treatment. The reverse was found when calves were treated according to threshold criteria, with ADG being the best target indicator for treatment. This was also the most beneficial strategy overall, with a significantly higher BPR value than any other strategy, but its degree of success depended on the chosen threshold of the indicator. The study shows strong support for TST, with all strategies showing improvements on calves treated selectively, compared with whole-herd treatment at 3, 8, 13 weeks post-turnout. The developed model appeared capable of assessing the consequences of other TST strategies on calf populations.
Influence on weaning weights of nursing beef cattle calves de-wormed 90days prior to weaning
2011, Livestock Science
Citation Excerpt :
Treatment groups were intermingled as necessary depending on pasture conditions and overall grazing logistics. Co-mingling of treatments was conducted to expose all calves to the similar indigenous parasite load similar to the work of Eddi et al. (1997), Hooke et al. (1997), and Ranjan et al. (1997). Bahiagrass (Paspalum notatum) pastures were grazed at each location.
Spring born beef calves (n = 568; 177.7 kg ± 34.0) at three different locations within the state of Florida were used to determine the efficacy of de-worming 90 days prior to weaning in order to achieve heavier weaning weights. Two or three breed types were available at each location and included Angus, Brangus, Brahman, or Romosinuano. Treatments included no de-worming protocol or de-worming of the nursing calf with doramectin injectable (1 mL/50 kg BW). Within a location, cow-calf pairs from both treatment groups were managed identically. Across all locations, de-wormed calves gained more total weight (P < 0.001) and ADG was 6.5% greater (P < 0.001) compared with non de-wormed calves. Our results indicated an animal performance advantage and a positive return on investment from de-worming nursing calves 90 days before weaning.
A meta-analysis of the milk-production response after anthelmintic treatment in naturally infected adult dairy cows
2004, Preventive Veterinary Medicine
Meta-analysis was used to estimate the effects of anthelmintic treatment on milk production in dairy cows. The literature search included peer-reviewed journals (both full articles and abstracts), conference proceedings and theses and included documents written in English, Spanish, French, Portuguese or Italian. The study outcome was defined as the difference in milk production (kg/cow per day) between treated and untreated cows. Random effect meta-analyses were performed on 75 trials published between 1972 and 2002. The combined estimate after controlling for publication bias and/or small-study effect was of 0.35 kg/cow per day. Significant variation among studies was detected and although several variables were associated with the study outcome, they did not significantly reduce the unexplained variability among trials. Trials reporting the use of endectocides had higher milk-production response compared with trials using older anthelmintics. Similarly, whole-herd treatment trials or trials which applied the treatment in mid-lactation or strategically throughout the year had higher response compared with calving or dry-period treatment trials. Trials reporting the results as total 305-day milk production had lower response compared with trials which measured production as daily milk weight. Primiparous cows trials had lower responses compared with multiparous cows trials.
Efficacy of different dosages of ivermectin injectable against the Hypoderma spp. in yaks
2003, Veterinary Parasitology
A chemotherapy trial was conducted to determine the lowest dosage of injectable preparation of ivermectin against Hypoderma spp. infestation in yaks in Tibetan areas in Tianzhu county, Gansu province, in northwest of China. One hundred and sixty yaks were randomly divided into four groups of 40 yaks for the trial. The first three groups were treated by subcutaneous injection in the neck with 0.1% ivermectin (respectively, 1, 5, 10 μg/kg body weight). The fourth group was not treated and considered as control group. All the experiments were performed in November 2000 and the animals were examined for the presence of warbles in the next March and May. The results indicated that there was no warbles found on the back of treated animal while third stage larvae were palpated on back of some of the yaks in control group. It is concluded that dosage of 1 μg/kg ivermectin injectable was sufficient to kill or stop development of larvae of Hypoderma spp. in naturally infected yaks if administrated in November.
Increase in milk yield following eprinomectin treatment at calving in pastured dairy cattle
2002, Veterinary Parasitology
Gastrointestinal nematodes rarely cause signs of clinical disease in adult cattle. However, they have been shown to exert a negative impact on production in lactating animals, as seen by improved production following elimination of the worms using anthelmintics. A double blind, randomized clinical trial was performed in 28 dairy herds in Canada. The objective of the study was to evaluate the effect of treatment with eprinomectin pour-on solution (IVOMEC^® EPRINEX^®) at calving on production, in cattle that have had some exposure to pasture. Cows were randomly allocated to treatment or placebo in blocks of 10, based on calving date, and treated with eprinomectin or placebo on the day of calving.
Information on milk production was obtained from all animals, as well as recorded cases of selected diseases. Milk production results from the Canadian dairy herd management system database were analysed using a mixed model with herd as a random effect and test within-cow as a repeated measurement. Test day milk yields from the first six tests after treatment were included in the model, representing a period of between 180 and 200 days in milk (dim). Treated cows produced an additional 0.94 kg of milk per day when compared to the controls over this period. The production effect was independent of calving season, age of the animal and geographical location. No effect of treatment was seen on milk composition, somatic cell count (scc) or on the selected health parameters that were recorded for all included animals.
Monthly fecal egg counts (FEC) were performed for eight randomly selected animals in each herd. The observed FEC were low in this study, with a range from 0 to 419 trichostrongyle type eggs per 5 g (ep5g) of feces in animals not yet treated with the anthelmintic. The average count was 9.8 and the median was 1.0. FECs dropped immediately after calving and stayed lower for at least 100 days in treated animals when compared to controls.
In conclusion, gastrointestinal nematodes appear to have an effect on milk production in Canadian dairy cows that have had some degree of pasture exposure. Eliminating the present subclinical parasite burdens produced a consistent increase in milk production that can yield economic benefits for the dairy producer.

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¹: Deceased.

²: Current address: Pfizer Animal Health, North American Region, Exton, PA 19341, USA.

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Comparative persistent efficacy of doramectin, ivermectin and fenbendazole against natural nematode infections in cattle

Abstract

Vet. Parasitol.

Int. J. Parasitol.

Vet. Parasitol.

Vet. Clin. North Am.