Efficacy of moxidectin against sarcoptic mange and effects on milk yield of ewes and growth of lambs

Pharmacokinetic and pharmacodynamic considerations for treating sarcoptic mange with cross-relevance to Australian wildlife

Sarcoptes scabiei is the microscopic burrowing mite responsible for sarcoptic mange, which is reported in approximately 150 mammalian species. In Australia, sarcoptic mange affects a number of native and introduced wildlife species, is particularly severe in bare-nosed wombats (Vombatus ursinus) and an emerging issue in koala and quenda. There are a variety of acaricides available for the treatment of sarcoptic mange which are generally effective in eliminating mites from humans and animals in captivity. In wild populations, effective treatment is challenging, and concerns exist regarding safety, efficacy and the potential emergence of acaricide resistance. There are risks where acaricides are used intensively or inadequately, which could adversely affect treatment success rates as well as animal welfare. While reviews on epidemiology, treatment strategies, and pathogenesis of sarcoptic mange in wildlife are available, there is currently no review evaluating the use of specific acaricides in the context of their pharmacokinetic and pharmacodynamic properties, and subsequent likelihood of emerging drug resistance, particularly for Australian wildlife. This review critically evaluates acaricides that have been utilised to treat sarcoptic mange in wildlife, including dosage forms and routes, pharmacokinetics, mode of action and efficacy. We also highlight the reports of resistance of S. scabiei to acaricides, including clinical and in vitro observations.

Survey of mange mite infesting sheep in Riyadh region, Saudi Arabia

The study was performed to survey the Sarcoptic mange in sheep and the effect of infection on the local strains during a specific period in different regions of Riyadh, Saudi Arabia. A total of 1745 sheep were examined clinically and were selected from the suspected cases for laboratory investigation of skin scrapings for disease diagnosis. The examined animals included (509) Naimi, (396) Najdi, (518) Hurri, and (322) Rufidi native sheep.

The results showed that the infestation rate was (12.77%) in all sheep. The highest strain was recorded (17.2%, 14.3%, 9.6%, and 8.6%), respectively. The infestation was highest in sheep over two years of age (15.2%) while it was lowest in sheep under two years of age (11.2 %). In addition, the infection rate in females was higher than in males. The prevalence of mange mites in females was (14%) compared to (11.2%) in males. The highest percentage of infestation was recorded in the head region at 67.2%, followed by that in the neck (4.4%), back (16.5%), tail (11.6%), and legs (0%).

The presence of mange mites was discovered by microscopic examination of deep skin scrapings of infected animals that were identified morphologically. The infection was assured by histological investigations. This study revealed that mange mite is one of the most significant sheep health constraints in Riyadh. Therefore, proper prevention measures must be implemented to take into consideration other non-host-related risk factors.

Amelioration of Sarcoptic Mange-Induced Oxidative Stress and Growth Performance in Ivermectin-Treated Growing Rabbits Using Turmeric Extract Supplementation

Simple Summary

Sarcoptic mange is a common rabbit disease that can be spread directly from sick to healthy rabbits. Infection in rabbits causes intense pruritus, head shaking, and scabby lesions on the inner side of the pinnae and on the external ear canal, as well as diminished growth performance and an increased rate of oxidative stress. Ivermectin has been shown to be an effective treatment for sarcoptic mange in rabbits; however, it has side effects on their performance. Botanicals such as turmeric extract have a remarkable antioxidant potential contributing to the deterrence of Sarcoptes-induced oxidative discrepancy in rabbits. The goal of this study was to investigate if turmeric extract can alleviate side effects in Ivermectin-treated rabbits while simultaneously improving their performance and antioxidant status. The results indicated that turmeric extract was utilized with varied efficacy against mites, and also helped rabbits recover faster and improved Ivermectin’s miticidal efficacy by improving performance and compromised immunity. Turmeric extract has strong antioxidant properties, suggesting that it could be used as an adjunctive remedy to reduce the side effects of Ivermectin while treating clinical rabbit sarcoptic mange. Furthermore, no adverse effects were observed in turmeric extract adjunctively supplemented rabbits, and the provided dose regimen of these supplements was found to be safe.

Abstract

In this experiment, the protective effect of turmeric extract (TE) on side effects of Ivermectin-treated rabbits, while improving their performance, blood characteristics, and antioxidant status, was investigated. Sixty-three clinically Sarcoptes-infested rabbits aged 60 days were randomly allocated into three groups, with 21 rabbits in each group, to receive either no TE or TE supplementation (1 or 2 mg/kg diet) for 30 days after being subcutaneously injected with Ivermectin (IVM) 1% w/v at a dose of 0.2 mg/kg body weight twice a week. Another 21 healthy rabbits were used as the control. Treatment with IVM + 1 and 2 mg TE improved body weight (BW), body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) in infested rabbits (p < 0.05). The IVM alone treatment had the highest mortality rate compared with the other treatments. Rabbits treated with IVM + 1 and 2 mg TE demonstrated progressive recovery manifested by improved nutrient digestibility and nitrogen balance. On day 7, the serum total protein, albumin, and albumin/globulin (A/G) ratio were significantly lower in the treated groups compared with the control group; also, the lowest values were observed in rabbits treated only with Ivermectin, followed by IVM + 1 and 2 mg TE. Treated rabbits had higher thiobarbituric acid reactive substance (TBAR) levels, but lower total antioxidant capacity (TAC), superoxidase dismutase (SOD), and glutathion peroxidase (GSH-Px) levels compared with the control group. On day 30 post-treatment, the rabbits in the IVM + 1 and 2 mg TE treatment groups showed progressive recovery manifested by improved biochemichal parameters, as well as a remarkable improvements in the oxidant/antioxidant balance towards normalcy (p < 0.05), and became comparable to that of the control compared with IVM alone treatment. In conclusion, turmeric extract improved rabbits’ performance toward normalcy, and has remarkable antioxidant properties and can be used in conjunction with a miticide to treat sarcoptic mange in rabbits.

The Pattern of Blood-Milk Exchange for Antiparasitic Drugs in Dairy Ruminants

Simple Summary

This review article is focused on the description of the plasma–milk partition coefficients for different antiparasitic drug classes in dairy ruminants, and it contributes to rational pharmaco-therapy in lactating dairy animals, which is critical to understand the pattern of drug excretion in milk as well as the residual concentration patterns in dairy products elaborated by processing milk from drug-treated animals.

Abstract

The prolonged persistence of milk residual concentration of different antiparasitic drugs in lactating dairy animals should be considered before recommending their use (label or extra-label) for parasite control in dairy animals. The partition blood-to-milk ratio for different antiparasitic compounds depends on their ability to diffuse across the mammary gland epithelium. The high lipophilicity of some of the most widely used antiparasitic drugs explains their high partition into milk and the extended persistence of high residual concentrations in milk after treatment. Most of the antiparasitic drug compounds studied were shown to be stable in various milk-related industrial processes. Thus, the levels of residues detected in raw milk can be directly applicable to estimating consumer exposure and dietary intake calculations when consuming heat-processed fluid milk. However, after milk is processed to obtain milk products such as cheese, yogurt, ricotta, and butter, the residues of lipophilic antiparasitic drugs are higher than those measured in the milk used for their elaboration. This review article contributes pharmacokinetics-based information, which is useful to understand the relevance of rational drug-based parasite control in lactating dairy ruminants to avoid undesirable consequences of residual drug concentrations in milk and derived products intended for human consumption.

A systematic review of moxidectin as a treatment for parasitic infections in mammalian species

Moxidectin (MOX) is a macrocyclic lactone approved worldwide for the treatment of both endo- and ecto-parasites in many mammalian species. The aim of this study was to assess the efficacy of MOX as a treatment against parasites in a range of mammalian species. An electronic literature search was performed for publications to the 1^st September 2020. A total of 205 papers were retrieved and screened against all required criteria; hence, 35 were papers were reviewed in this study. The level of evidence and methodological quality was analysed, where a total of 13 publications were categorised as a 'randomised control trial', seven were categorised as a 'non-randomised control trial' and 15 as an 'experimental control trial'. The overall methodological quality of the publications was considered low, low to moderate, moderate, moderate to high and high in ten, four, twelve, five and a further four, respectively. We assessed the treatment and possible toxicity of MOX in 13 mammalian species, six investigations reported adverse effects to MOX in a small percentage of individuals. The authors reported observed reactions that were typically mild symptoms that did not require additional therapies, and/or resolved themselves. Further studies are needed to assess the efficacy of MOX treatment in a larger number of species, particularly in wildlife.

The scabicide effect of moxidectin in vitro and in experimental animals: Parasitological, histopathological and immunological evaluation

Scabies is considered one of the commonest dermatological diseases that has a global health burden. Current treatment with ivermectin (IVM) is insufficient and potential drug resistance was noticed. Moxidectin (MOX), with a better pharmacological profile may be a promising alternative. The efficacy of moxidectin against Sarcoptes scabiei was assessed both in vitro and in vivo in comparison with ivermectin. For the in vitro assay, both drugs were used in two concentrations (50 μg/ml and 100 μg/ml). For the in vivo assay, twenty rabbits infected with Sarcoptes scabiei were divided into three groups: untreated, moxidectin-treated and ivermectin-treated with the same dose of 0.3 mg/kg once. Another four rabbits were used as a normal control non-infected group. Treatment efficacy was evaluated by clinical assessment, parasitological evaluation and histopathological examination of skin samples using Hematoxylin and eosin and toluidine blue for mast cell staining. Immune response was also assessed by immunohistochemical staining of CD3 T cells in skin samples. Our results showed that moxidectin had a high efficacy (100%) in killing mites when used in both concentrations (50 μg/ml, 100 μg/ml) in the in vitro assay. Concerning the in vivo assay, on day 14 post-treatment, all MOX-treated rabbits were mite-free with full clinical cure by the end of the study (D21) showing (100%) reduction of mites count. Also, marked improvement in the epidermis with absence of mites in skin samples were shown. Poor clinical and parasitological improvements were noted in the ivermectin-treated rabbits, when given as a single dose with a percentage reduction (60.67%) in the 2nd week and progressive increase in lesions and mites count in the 3rd week post-treatment. Regarding the immune response, MOX-treated group showed mild infiltration with both mast cells and CD3 T cells in comparison to severe infiltration with both types of cells in the untreated and IVM-treated group. On conclusion, our results demonstrated that a single dose of MOX was more effective than IVM, supporting MOX as a valuable therapeutic approach for scabies therapy.

The effects of heat applications on macrocyclic lactone-structured antiparasitic drug residues in cows' milk

The study aimed to evaluate the effects of heat on macrocyclic lactone residues in cows' milk. Ivermectin, abamectin, doramectin, eprinomectin and moxidectin were added to raw milk in three concentrations. The milk was then pasteurised (40 seconds at 74°C or 1 minute at 80°C) and boiled (10 minutes at 100°C). The analyses were performed with a validated method: LC-MS/MS. Thermal treatment resulted in a statistically significant decrease in the abamectin, eprinomectin, and moxidectin concentrations in the milk; however, the residues did not completely degrade. Boiling resulted in a greater decrease in the moxidectin concentrations than was observed with pasteurisation. The high pasteurisation and boiling processes had a greater effect on the eprinomectin residues than did the low pasteurisation process. The pasteurisation and boiling processes did not have an effect on the doramectin and ivermectin. The study concluded that the macrocyclic lactones are generally resistant to such processes.

In Vitro Efficacy of Moxidectin versus Ivermectin against Sarcoptes scabiei

Moxidectin is under consideration for development as a treatment for human scabies. As some arthropods show decreased sensitivity to moxidectin relative to ivermectin, it was important to assess this for Sarcoptes scabieiIn vitro assays showed that the concentration of moxidectin required to kill 50% of mites was lower than that of ivermectin (0.5 μM versus 1.8 μM at 24 h; P < 0.0001). This finding provides further support for moxidectin as a candidate for the treatment of human scabies.

Treatment strategies for sheep scab: An economic model of farmer behaviour

Ovine psoroptic mange (sheep scab) is a debilitating and damaging condition caused by a hypersensitivity reaction to the faecal material of the parasitic mite Psoroptes ovis. Farmers incur costs from the use of prophylactic acaricides and, if their sheep become infected, they incur the costs of therapeutic treatment plus the economic loss from reduced stock growth, lower reproductive rate, wool loss and hide damage. The unwillingness of farmers to use routine prophylactic treatment has been cited as a primary cause of the growing incidence of sheep scab in the United Kingdom (UK) since the disease was deregulated in 1992. However, if farmers behave rationally from an economic perspective, the optimum strategy that they should adopt will depend on the risk of infection and the relative costs of prophylactic versus therapeutic treatment, plus potential losses. This calculation is also complicated by the fact that the risk of infection is increased if neighbours have scab and reduced if neighbours treat prophylactically. Hence, for any farmer, the risk of infection and optimum approach to treatment is also contingent on the behaviour of neighbours, particularly when common grazing is used. Here, the relative economic costs of different prophylactic treatment strategies are calculated for upland and lowland farmers and a game theory model is used to evaluate the relative costs for a farmer and his/her neighbour under different risk scenarios. The analysis shows that prophylaxis with organophosphate (OP) dipping is a cost effective strategy, but only for upland farmers where the risk of infection is high. In all other circumstances prophylaxis is not cost effective relative to reliance on reactive (therapeutic) treatment. Hence, farmers adopting a reactive treatment policy only, are behaving in an economically rational manner. Prophylaxis and cooperation only become economically rational if the risk of scab infection is considerably higher than the current national average, or the cost of treatment is lower. Should policy makers wish to reduce the national prevalence of scab, economic incentives such as subsidising the cost of acaricides or rigorously applied financial penalties, would be required to make prophylactic treatment economically appealing to individual farmers. However, such options incur their own infrastructure and implementation costs for central government.

Mange mite infestation in small ruminants in Ethiopia: Systematic review and meta-analysis

Mange mites are economically important ectoparasites of sheep and goats responsible for rejection or downgrading of skins in tanneries or leather industries in Ethiopia. The objective of this systematic review was to compute the pooled prevalence estimate and identify factors influencing mange mite prevalence in sheep and goats at national level based on the available research evidence. Articles on mange mite infestation of small ruminants in Ethiopia were searched in PubMed, Web of Science, Google scholar and African journals on-line. The review was based on 18 cross-sectional studies carried out between 2003 and 2015 in four administrative states of Ethiopia. Accordingly, the pooled prevalence estimate in a random effects meta-analysis was estimated to be 4.4% (95% CI 3.0, 6.3) although there were evidence of a substantial amount of between-study variance (I(2)=98.4%). In subgroup and multivariable meta-regression analyses, animal species, agro-ecology and administrative state were found to have significant effect on the prevalence estimate (P<0.05) and explained 32.87% of the explainable proportion of the heterogeneity noted between studies The prevalence was found to be higher in goats in lowland agro-ecology. Region wise the highest estimate was calculated for Amhara (6.4%) followed by Oromia (4.7%), Tigray (3.6%) and Southern Nations, Nationalities and People Region (SNNPR) (3.1%). Significant difference was noted between Amhara and SNNPR. The study further revealed that mites of the genus Sarcoptes, Demodex and Psoroptes are the most prevalent mites infesting small ruminants in Ethiopia. Valid studies were lacking from five regional states. As some of these regions are known for their large small ruminant population, further studies are warranted to produce better picture of the infestation at a national level. Meanwhile, the need for monitoring the ongoing control intervention is suggested.

Effect In Vitro of Antiparasitic Drugs on Microbial Inhibitor Test Responses for Screening Antibiotic Residues in Goat's Milk

Microbial inhibitor tests are widely used to screen antibiotic residues in milk; however, these tests are nonspecific and may be affected by various substances capable of inhibiting the growth of the test microorganism. The objective of this study was to determine the effect of antiparasitic drugs in goat's milk on the microbial inhibitor test response. Raw antibiotic-free milk from Murciano-Granadina goats was supplemented with eight concentrations of seven antiparasitic substances (albendazole, 10 to 170 mg/kg; closantel, 1 to 140 mg/kg; diclazuril, 8 to 45 mg/kg; febendazole, 10 to 140 mg/kg; levamisole, 40 to 440 mg/kg; diazinon, 8 to 45 mg/kg; and ivermectin, 40 to 200 mg/kg). Twelve replicates for each concentration were analyzed with three microbial inhibitor tests: BRT MRL, Delvotest SP-NT MSC, and Eclipse 100. The results were interpreted visually (negative or positive). Using a logistic regression model, the concentrations of the antiparasitic drugs producing 5% (IC5), 10% (IC10), and 50% (IC50) positive results were determined. In general, the Eclipse 100 test was less sensitive to the effect of antiparasitic substances; the inhibitory concentrations of almost all the drugs assayed were higher than those for other tests. Conversely, the BRT MRL test was most affected, with high levels of interference at lower antiparasitic drug concentrations. Closantel and diazinon interfered with all microbial tests at lower concentrations than did other drugs (IC5 = 1 to 26 and 12 to 20 mg/kg, respectively), and higher concentrations of levamisole and diclazuril (IC5 = 30 to 240 and 50 to 117 mg/kg, respectively) were required to produce 5% positive results. These findings indicate that microbial inhibitor tests can be affected by elevated concentrations of antiparasitic drugs in goat's milk.

Interactions between parasitic infections and reproductive efficiency in sheep

This review article summarises the many reports in the literature, confirming that, in sheep, parasitic infections can adversely affect reproductive efficiency; examples, which refer to all parts of the reproductive cycle of sheep, are as follows: trichostrongylosis in ewe-lambs (which can lead to delayed attainment of puberty), myiosis of the prepuce (which can cause impediment of mating), chorioptic mange or trypanosomosis in rams (which can lead to testicular degeneration or azoospermia, respectively), trypanosomosis or sarcoptic mange in pre-conceptual ewes (which can lead to poor conception rates or reduced number of ovulations, respectively), toxoplasmosis or neosporosis in pregnant ewes (which are causes of abortion), trichostrongylosis or trematode infections in lactating ewes (which can cause reduction of milk yield and can be a risk factor for mastitis, respectively), cryptosporidiosis in newborn lambs (which can be a cause of deaths), coccidiosis in growing pre-weaned lambs (which can cause suboptimal growth rate). In other cases, the reproductive status of the animal can influence the parasitic infection; examples are as follows: the increase in faecal parasitic output during the peri-parturient period (as a consequence of the peri-parturient relaxation of immunity), the heavier trichostrongylid infections of twin lambs compared to lambs from single parities (as a consequence of developmental origin issues in twin lambs). All the above examples support the idea of presence of interactions between parasitic infections and reproductive efficiency in sheep.

Moxidectin efficacy in a goat herd with chronic and generalized sarcoptic mange

A case of sarcoptic mange affecting almost all the animals of a dairy goat herd is described. This pruritic skin disease led progressively to high mortality and dramatic drop of milk yield. The lesions of the affected goats were typical of a chronic and generalized-diffuse sarcoptic mange. Diagnosis was confirmed by skin scrapings and histopathology in which many mites were demonstrated. All surviving goats were treated with injectable moxidectin solution 1% (CYDECTIN-Fort Dodge) at the dose of 0.2 mg/kg, applied every 15 days for four times, subcutaneously. Although pruritus had decreased soon after the first treatment, a satisfactory healing of cutaneous lesions was witnessed 6 weeks after the beginning of moxidectin trial. Parasitological cure was achieved in all affected animals by the end of the trial. In the four monthly followups, no evidence of sarcoptic mange could be found.

Sarcoptes-World Molecular Network (Sarcoptes-WMN): integrating research on scabies

Parasites threaten human and animal health globally. It is estimated that more than 60% of people on planet Earth carry at least one parasite, many of them several different species. Unfortunately, parasite studies suffer from duplications and inconsistencies between different investigator groups. Hence, groups need to collaborate in an integrated manner in areas including parasite control, improved therapy strategies, diagnostic and surveillance tools, and public awareness. Parasite studies will be better served if there is coordinated management of field data and samples across multidisciplinary approach plans, among academic and non-academic organizations worldwide. In this paper we report the first 'Living organism-World Molecular Network', with the cooperation of 167 parasitologists from 88 countries on all continents. This integrative approach, the 'Sarcoptes-World Molecular Network', seeks to harmonize Sarcoptes epidemiology, diagnosis, treatment, and molecular studies from all over the world, with the aim of decreasing mite infestations in humans and animals.

Treatment and control of ectoparasites in sheep

Ectoparasites are a major concern in sheep flocks, wherever sheep are kept. Techniques to control and eradicate lice, ked, or scab have been available since the beginning of the 20th century, but the parasites still exist. Sheep scab (Psoroptes ovis) was eradicated from Australia in the late 1800s, before many of the more effective chemicals were available, and sheep ked is believed to also have been eradicated. Sheep scab has also been eradicated from North America. This article provides an overview of the common ectoparasites of sheep, effective products to control these parasites, and management factors that affect the success of these treatments.

Cross-sectional sero-epidemiological survey of sarcoptic mange in sheep of Western Castile and Leon, Spain

The aim of the present study was to determine the prevalence of Sarcoptes scabiei-infection of ovine livestock in three provinces (Leon, Zamora and Salamanca) in the Western part of the Castile and Leon region in Spain, and to determine the association between different variables and seropositivity. A total of 3730 sheep sera from 373 flocks (10 sera from each flock) collected from May to September over the course of the years 2006 and 2007 were individually analysed by an indirect antibody ELISA validated for diagnosing sarcoptic mange in sheep. The overall flock-level true prevalence was 22.6% (95% CI: 17.8-27.4), the overall individual-level true prevalence within the total flocks was 7.2% (95% CI: 6.1-8.3) and the overall individual-level true prevalence within the seropositive flocks was 31.3% (95% CI: 27.2-35.4). The apparent prevalences, at flock-level and at individual-level within the total flocks and within the seropositive flocks, were not statistically different (p > 0.05) when the primary production objective of the flock is milk vs. meat, or in smaller (< or = 276 sheep, 50th percentile) vs. larger flocks (> 276 sheep). The apparent prevalences, at flock-level and at individual-level within the seropositive flocks, were, likewise, not statistically different between the three provinces, but the individual-level apparent prevalence within the total flocks showed significant variation from one province to another (p < or = 0.05). Sheep maintained in the Provinces of Zamora and Salamanca had greater odds (OR = 1.7, 95% CI: 1.2-2.6; OR = 1.9, 95% CI: 1.3-2.8, respectively) of being seropositive than those located in Leon Province (OR = 1.0). The findings of the present study clearly show the need to implement in this region effective control measures against sarcoptic mange in sheep.

Clinical evaluation and antibody responses in sheep after primary and secondary experimental challenges with the mange mite Sarcoptes scabiei var. ovis

In this work the clinical evolution and the specific serum IgG and IgE antibody responses in sheep after primary (n=10) and secondary (n=4) experimental challenges with the mange mite Sarcoptes scabiei var. ovis were studied. The primary infection was characterized by the development of mange lesions in all sheep, a detection of live S. scabiei mites in 70% skin scrapings taken in week 10 post-challenge (PC), strongly raised and sustained specific IgG levels and a more moderate but continuous rise in specific IgE levels. Seroconversion was detected for IgG and IgE by ELISA in 90% and 60% of the sheep in week 8 PC, respectively. By Western-blotting (WB), ten IgG-reactive bands (36-120 kDa) and four IgE-reactive bands (90-180 kDa) were observed in week 8 PC. Following the secondary challenge the ewes developed a smaller area of mange lesion than that seen following primary challenge and live S. scabiei mites were not detected in skin scrapings collected in week 8 PC, suggesting that sheep had developed immunity to re-infection. Compared to primary infection, the specific IgG secondary antibody levels were transient, but in contrast there was an anamnestic IgE response, resulting in an elicitation of specific serum IgE levels in week 2 PC significantly higher than those demonstrated after primary infection. WB analysis revealed one additional IgG-reactive band (180 kDa) and no additional IgE-reactive bands. Determining the immunodiagnostic or vaccination value of the IgG-reactive antigens and IgE-reactive allergens detected requires further studies.

Sarcoptes mite from collection to DNA extraction: the lost realm of the neglected parasite

Sarcoptes mite from collection to DNA extraction forms the cornerstone for studies on Sarcoptes scabiei. Whilst the new science era took a shy leap into the different facets of mite studies, the cornerstone was almost entirely neglected. Mite collection, cleaning, storage and DNA extraction were, basically, humble attempts to extrapolate, adapt, modify or 'pirate' those existing methods to the peculiarities of Sarcoptes research. These aspects usually constituted few lines, bashfully mentioned, in the materials and methods section of some papers, which arose in unique problems concerning cost-effectiveness, time profitability, safety and even worse, the credibility of the results, creating contradictory conclusions in some cases. This 'noisy' situation encouraged us to collect, classify and review, for the first time to our knowledge, some aspects relating to studies on Sarcoptes mite from collection to DNA extraction, which will be useful for further studies on Sarcoptes, and have implications for the effective control of the diseases Sarcoptes mite causes. Further studies are needed, especially to compare the profitability, safety, sensibility and specificity of the different methods of this neglected realm of the ubiquitous ectoparasite.

Efficacy of crude neem seed kernel extracts against natural infestation of Sarcoptes scabiei var. ovis

This study was aimed to evaluate the efficacy of crude aqueous-methanol and aqueous extracts of neem (Azadirachta indica) seed kernel against sarcoptic mange of sheep. Crude aqueous-methanol (AME) and aqueous extracts (AE) of neem seed kernel (NSK) were prepared and formulated as 10% and 20% ointments (w/w), using Vaseline as vehicle. Forty-two lambs of Pak Karakul breed, having natural infection of sarcoptic mange were divided into seven experimental groups. Skin scrapings and clinical examination were carried out at scheduled intervals after treatment. Ivermectin (positive control) completely cleared infesting mites from animals after 10 days and 20% AME after 16 days. While, clinical mange was completely cured after 16 and 20 days with ivermectin and 20% AME, respectively, under field conditions. Only the higher concentration (20% AME) of NSK extracts completely cured the clinical mange, suggesting a dose-dependent response. Our results consolidate the belief that use of folk remedies can provide an effective and economic way of combating sarcoptic mange in sheep.

Sarcoptic mange in three alpacas treated successfully with amitraz

Sarcoptic mange is a serious skin disease in alpacas that can result in high morbidity and even mortality. Three alpacas were presented with sarcoptic mange that had previously failed to respond to repeated topical applications of eprinomectin, and an injection of doramectin. They were moderately to severely pruritic, had extensive lesions of alopecia, erythema, scaling and crusting, and had lost weight. As no drug is currently licensed for the treatment of sarcoptic mange in alpacas in the UK, they were treated with a topical solution of amitraz (50 mL in 10 L) after initial bathing with antibacterial or keratolytic shampoos. The clinical signs completely resolved with no relapse over a 10-month follow-up period. In this small group of alpacas, amitraz was an effective and well-tolerated treatment for sarcoptic mange.

Pattern of eprinomectin milk excretion in dairy sheep unaffected by lactation stage: comparative residual profiles in dairy products

Eprinomectin (EPM) is a broad-spectrum endectocide compound approved for use in dairy cattle with a zero milk-withdrawal period, but has not been registered for use in lactating dairy sheep. The pattern of EPM excretion in milk was comparatively characterized following its pour-on administration (500 microg/kg) to lactating dairy sheep at two different stages of lactation. The relationship between milk excretion and plasma disposition kinetics of EPM was characterized. Residual EPM concentrations were assessed during cheese making (whey and curd) and ripening (cheese) by high-performance liquid chromatography and fluorescence detection. EPM was poorly distributed from the bloodstream to the mammary gland and low concentrations were excreted in milk. The level of milk production (early-mid and mid-late lactation) did not affect either the plasma-milk distribution or the pattern of residual concentrations in milk. During cheese making, the highest residual concentrations of EPM were measured in the curd, which increased during cheese ripening, reaching a maximum after 40 days. However, these residual concentrations were below the maximum residue limit of 20 ng/ml established for EPM in bovine's milk. Therefore, these dairy products could be considered safe for consumers after the EPM antiparasitic pour-on treatment (500 microg/kg) in lactating dairy sheep.

Clinical and therapeutic studies on mange in horses

At Kafr El-Sheikh province, Egypt, out of 117 examined drafting horses, mites were detected in 20 (17.09%) horses. The recovered mites were 14 Chorioptes, four Psoroptes and two Sarcoptes whereas mites were not detected in four cases clinically showed typical mange lesions. Interestingly, neither the age nor the sex of the examined horses had a clear influence on the prevalence of the infection. Clinical signs observed in mange infested horses were in the form of irregular skin lesions, severe itching and sometimes biting of affected skin areas and decrease feed consumption. The skin lesions mainly start as erythematous area followed by developing of papules and crust formation. Skin scratches as a result of traumatized lesions usually occurred. Hair was lost on the affected parts developing irregular alopecic areas. Distribution of the lesions was varied according to the type of mite. Chorioptic mite was detected in para-anal fold, distal portion of legs and tail lesions, Psoroptic mite was detected in withers, mane, shoulder and flank lesions whereas Sarcoptic mite was isolated mainly from lesions on the head and neck. Complete clinical and parasitological cure for mite infestation were obtained within 2 weeks in both moxidectin and ivermectin treated groups with 100% recovery rate. Our results indicated that moxidectin oral gel is effective and good alternative for the treatment of chorioptic mange in horse to avoid drug resistance that may develop as a result of the intensive use of ivermectin alone for long periods.

Use of doramectin for treatment of sarcoptic mange in five Angora rabbits

The efficacy of administering doramectin after moxidectin treatment, which has previously proved only partially effective, was evaluated in five Angora rabbits naturally infested with Sarcoptes scabiei mange. Evaluations included physical examination for clinical signs of sarcoptic mange and collection of skin scrapings for determination of mites. The rabbits first received two subcutaneous injections, 10 days apart, of moxidectin 1% injectable solution at a dosage of 0.2 mg kg(-1) of bodyweight. Although moxidectin treatment resulted in clinical improvement within 10 days post initial injection, on days 10 and 35 post initial treatment live mites were present in skin scrapings. Administration of doramectin 1% injectable solution using the same route and dosage and at similar intervals to moxidectin led to complete disappearance of signs of scabies and parasitological cure in all rabbits.

Milk excretion of ivermectin and moxidectin in dairy sheep: assessment of drug residues during cheese elaboration and ripening period

Ivermectin (IVM) and moxidectin (MXD) are broad-spectrum endectocide antiparasitic drugs extensively used in food-producing animals. The patterns of IVM and MXD excretion in milk were comparatively characterized following their subcutaneous administration (200 microg.kg(-1) of body weight) to lactating dairy sheep. The relationship between milk excretion and plasma disposition kinetics of both compounds was characterized. A pool of milk collected from all of the animals in each experimental group was used for cheese elaboration. IVM and MXD residual concentrations were assessed during the cheese-making process and ripening period. IVM and MXD concentrations were measured in plasma, milk, and milk product (whey, curd, and cheese) samples using an HPLC-based methodology with fluorescence detection. IVM and MXD were extensively distributed from the bloodstream to the mammary gland, and large quantities, particularly of MXD, were excreted in milk. Residual concentrations of both compounds were recovered in milk up to 30 (IVM) and 35 (MXD) days post-treatment. The total fraction of the administered dose excreted in milk for MXD was significantly higher than that of IVM. During cheese production, the highest residual concentrations of both molecules were measured in the curd. Thirty-four percent of the total drug residue measured in the pooled milk collected from treated sheep was lost during the cheese-making process. The lowest residual concentrations were measured in the whey. IVM and MXD concentrations in the elaborated cheese tended to increase during the ripening period, reaching the highest residual level at 40 days of cheese maturation. The long persistence of milk residual concentrations of MXD and IVM in lactating dairy sheep and the high concentrations found in cheese and other milk-related products should be seriously considered before recommendation of the extralabel use of these antiparasitic drugs in dairy animals.

Disposition of doramectin milk residues in lactating dairy sheep

Doramectin (DRM) is a broad spectrum macrocyclic lactone antiparasitic drug not approved for use in dairy animals. However, DRM and other endectocide compounds are widely used extra-label to control endo- and ectoparasites in dairy sheep. The plasma disposition kinetics and the pattern of DRM excretion in milk were characterized following its subcutaneous administration to lactating dairy sheep. DRM concentration profiles were measured in plasma and milk samples after validation of a specific HPLC-based methodology. DRM was detected between 1 h and 30 days post-treatment. DRM concentrations of 0.48 ng.mL(-1) (plasma) and 1.03 ng.mL(-1) (milk) were measured at 30 days post-treatment. DRM was extensively distributed from the bloodstream to the mammary gland, and large concentrations were excreted in milk. The peak concentrations and total amount of DRM recovered in milk (expressed as area under the concentration versus time curve) were 3-fold higher than those measured in plasma; 2.44% of the total DRM dose was excreted in milk. The long persistence of DRM milk residues should be seriously considered before its extra-label use in dairy animals is recommended.

Determination of ivermectin and moxidecin residues in bovine milk and examination of the effects of these residues on acid fermentation of milk

Ivermectin (IVM) and moxidectin (MXD) are broad-spectrum antiparasitic drugs not approved for use in dairy animals, although their use in dairy sheep, goats and cattle nevertheless occurs in many parts of the world. The work reported here describes (1) the application of an HPLC method (including milk samples clean-up and chemical extraction) to quantify IVM and MXD residues in bovine milk, and (2) an assessment of the effect of different IVM and MXD concentrations on bovine milk acid fermentation. The latter was carried out using the 'yoghurt test' to determine the minimum IVM and MXD concentrations affecting milk acid fermentation. The sample clean-up, chemical extraction and the validated HPLC method allowed the quantification of IVM and MXD up to 0.1 ng ml(-1) in milk with acceptable validation coefficients. Drug recoveries from fortified milk samples ranged between 72% (CV = 9.1%) and 75% (CV = 13.3%) for MXD and IVM, respectively. Neither IVM nor MXD affected the acid fermentation of bovine milk. In fact, there was no drug-induced changes on milk acidity even at IVM and MXD concentrations as high as 1000 ng ml(-1). These results indicate that the yoghurt biological test is not suitable to evaluate the presence of milk residues for these antiparasitic compounds. Thus, a highly sensitive HPLC technique is the only reliable method for determining the presence of residual concentrations of IVM and MXD in milk and dairy products to assure consumer safety.

Efficacy of moxidectin 1% injectable against natural infection of Sarcoptes scabiei in sheep

Thirty ewes naturally infected with Sarcoptes scabiei var. ovis, were allocated into three groups of 10 animals each. Animals in groups B and C were treated on day 0 and on days 0 and +10, respectively, with moxidectin 1% injectable at a dose of 0.2mg moxidectin/kg body weight (BW). Group A remained untreated. Seven days before treatment, the geometric mean of Sarcoptes scabiei var. ovis per square centimeter of skin in groups A, B and C were not significantly different. From the day of treatment to the end of the trial, the average number of mites/cm(2) increased in untreated animals and decreased in groups B and C, but these values were higher for group C. Active lesions produced by S. scabiei var. ovis consistently increased during the trial in the untreated animals; in group B the minimum count occurred on day +56 this reduction being more evident in group C (no lesions on days +49 and +56). Also in this group, the number of cured animals was 100%, therefore, the application of two treatments with moxidectin (group C) showed higher efficacy than a single treatment (group B). Body condition score decreased in the three experimental groups along the trial. All animals were individually weighed on days -1, +28 and at the end of the trial. No adverse reactions were observed in the animals treated with 0.2mg moxidectin/kg BW.

Ectoparasite control in small ruminants

Ectoparasites are a common problem in small ruminants of North America. Management of ectoparasites in small ruminants can be challenging for producers and veterinarians. It is important for the veterinarian to make an accurate diagnosis of the type of ectoparasite that is infesting the animal, then to develop a plan that most effectively and economically controls the ectoparasite. Effective and economic control of an ectoparasite infestation begins with an understanding of the ectoparasite's life cycle and how that life cycle affects the animal. It should be noted that climate and geographical area can affect the life cycle of specific ectoparasites, so it is important for veterinarians to educate themselves about their specific environment. Once the life cycle has been addressed, then the veterinarian should decide which intervention will provide the best control. Intervention possibilities may range from insecticides to environmental management or a combination of several methods. The veterinarian should provide the producer with realistic goals that define specific limitations of ectoparasite control.

Effects of sarcoptic mange on the reproductive performance of ewes and transmission of Sarcoptes scabiei to newborn lambs

In each of two experiments, the reproductive performance of ewes naturally infested with sarcoptic mange and of uninfested ewes was assessed in in-season natural breeding conditions (experiment I) or in out-of-season controlled breeding conditions (experiment II). A statistically significant difference was observed in the total lambs born per ewe (infested ewes, 1.2; controls, 1.6), in the liveborn lambs per ewe (infested ewes, 1.2; controls, 1.5) and in the lamb body weight per ewe (infested ewes, 3.33kg; controls, 4.53kg) under natural breeding conditions, as well as in the lamb body weight per ewe (infested ewes, 3.37kg; controls, 4.14kg) among ewes under controlled breeding conditions. No adverse effects were observed in the other reproductive indices, cycling rate, mating rate, return-to-oestrus rate, abortion rate, lambing rate and stillbirth rate. Sarcoptic mange was observed in the offspring of infested ewes after 30 days and in the offspring of uninfested controls 60 days after their birth.