Topic:Anthelmintic Treatment
Anthelmintic treatment involves the use of drugs to control parasitic worm infections in horses. These treatments target various types of internal parasites, such as strongyles, ascarids, and tapeworms, which can affect equine health and performance. The administration of anthelmintics is a common practice in equine management to reduce parasite burdens and minimize the risk of disease transmission. Different classes of anthelmintics, including benzimidazoles, macrocyclic lactones, and pyrantel, are used based on the specific parasitic threats and resistance patterns. This page compiles peer-reviewed research studies and scholarly articles that explore the efficacy, resistance development, and management strategies associated with anthelmintic treatment in horses.
A model for the development and growth of the parasitic stages of Parascaris spp. in the horse. Literature documenting the growth and development of Parascaris spp. infections was used to develop a model describing worm dynamics in the young horse. The model incorporates four main variables; the rate at which larvae migrate through host tissues to return to the small intestine, the proportion of migrating larvae which succeed in returning to the small intestine, the rate of growth in size of maturing and adult worms and the survival rate of maturing and adult worms. In addition, the number of eggs laid each day by adult female worms is calculated as a function of worm size (length) and i...
Repeatability of strongyle egg counts in naturally infected horses. The selective treatment of horses is used to decrease the number of anthelmintic treatments by only treating a proportion of animals in the population. One way to select animals for treatment is to identify low and high egg-shedders using faecal egg counts (FEC); then to treat only the high egg-shedders. The value of this method is enhanced if differences among individuals in the level of egg-shedding remain consistent over time. One way to assess the stability of the rankings of animals over time is to measure the repeatability which is defined as the variance between horses divided by the to...
Ovicidal efficacy of fenbendazole after treatment of horses naturally infected with cyathostomins. The ovicidal activity of benzimidazole (BZ) anthelmintics is unique and not seen in other drug classes. Such ovicidal efficacy is not widely reported for equine cyathostomins, nor has this activity been tested in the face of BZ resistance. Although the product label states that fenbendazole is for use against BZ-susceptible cyathostomins, susceptibility testing is rarely performed. In this field-based study, the ovicidal efficacy of fenbendazole in horses (n=39) harbouring BZ-resistant cyathostomins was compared when dosed at 7.5mg/kg body weight (BW) orally, as a single dose per os (n=21) or ...
Preventive health care of Pony Club horses in rural New South Wales, Australia. To describe preventive health care provided to a cohort of Pony Club horses in rural New South Wales, Australia, and the associated veterinary involvement. Methods: Prospective longitudinal study Methods: Observational data collected for 48 Pony Club horses using daily owner-kept diaries and monthly veterinary visits for 9-12 months. Results: Frequency of healthcare events varied markedly between the horses; 54% of horses received 5 or more foot-care treatments, 69% received 1-3 anthelmintic treatments, 40% received dental care, 21% received chiropractic care; only 8% were vaccinated. Farriers...
Species composition of larvae cultured after anthelmintic treatment indicates reduced moxidectin susceptibility of immature Cylicocyclus species in horses. For the control of cyathostomins in horses, the macrocyclic lactones (MLs), moxidectin (MOX) and ivermectin (IVM) are the most commonly used anthelmintics. However, reduced activity, observed as shortening of the egg reappearance period (ERP) has been described. Shortening of the ERP may be caused by a decreased susceptibility of immature worms for MLs. Alternatively, immature worms may develop faster into egg producing adults as a result of repeated ML treatments. The species composition of the larval cultures obtained shortly after ML and pyrantel (PYR) treatment can confirm the hypothesis o...
Strongylids in domestic horses: Influence of horse age, breed and deworming programs on the strongyle parasite community. An extensive analysis of the relationships between strongylid egg shedding in domestic horses and the strongylid community structure in regard to the age of the horses, their breeds and different strategies of horse management, particularly with anthelmintic treatment programs was performed. Domestic horses (n=197) of different ages (5 months to 22 years) and of various breeds from 15 farms with different types of deworming programs were included in this study. Strongylids (totally, 82,767 specimens) were collected in vivo after deworming of the horses with the macrocyclic lactone anthelmintic...
Evaluation of activity of fenbendazole, oxibendazole, piperazine , and pyrantel pamoate alone and combinations against ascarids, strongyles, and strongyloides in horse foals in field tests on two farms in Central Kentucky in 2014 and 2015. Activity of fenbendazole (FBZ), oxibendazole (OBZ), piperazine (PIP) and pyrantel pamoate (PRT) alone and combinations of OBZ and PIP and of OBZ and PRT was evaluated against parascarids, strongyles and strongyloides in horse foals (n=281).This was on two farms - Farm A - mixed light-horses (n=26) and Farm B-Thoroughbreds (n=255) - in Central Kentucky in field tests in 2014 and 2015. Foals on both farms were treated one to three times each; an exception was that seven foals on Farm A were nontreated controls. Before treatment, the foals on Farm A were all weighed on scales but weights for Farm...
Colic in a working horse population in Egypt: Prevalence and risk factors. Colic is an important health problem in managed horse populations. Currently, there is limited information about colic prevalence and risk factors for colic in working horse populations. Objective: To determine the prevalence of, and risk factors for, colic in a working horse population in Egypt and to describe management practices in this working horse population. Methods: Cross-sectional survey. Methods: Owners of 350 working horses were interviewed. Data about their horses, management and colic episodes in the preceding 12 months were collected. Dental examination was conducted on 342 horse...
Use of a multiple choice questionnaire to assess UK prescribing channels’ knowledge of helminthology and best practice surrounding anthelmintic use in livestock and horses. Grazing livestock and equines are at risk of infection from a variety of helminths, for which the primary method of control has long been the use of anthelmintics. Anthelmintic resistance is now widespread in a number of helminth species across the globe so it is imperative that best practice control principles be adopted to delay the further spread of resistance. It is the responsibility of all who prescribe anthelmintics (in the UK, this being veterinarians, suitably qualified persons (SQPs) and pharmacists) to provide adequate information on best practice approaches to parasite control at t...
Negative covariance between parasite load and body condition in a population of feral horses. In wild and domestic animals, gastrointestinal parasites can have significant impacts on host development, condition, health, reproduction and longevity. Improving our understanding of the causes and consequences of individual-level variation in parasite load is therefore of prime interest. Here we investigated the relationship between strongyle fecal egg count (FEC) and body condition in a unique, naturalized population of horses that has never been exposed to anthelmintic drugs (Sable Island, Nova Scotia, Canada). We first quantified variation in FEC and condition for 447 individuals accordi...
Objective evaluation of two deworming regimens in young Thoroughbreds using parasitological and performance parameters. Parasitic helminths of equids are capable of causing ill-thrift, clinical disease, and death. Although young horses are the most susceptible to parasitic disease and are the most intensively treated cohort, deworming regimens are rarely evaluated within this age group. This study objectively evaluated the impact of deworming regimen on fecal egg counts (FECs), growth rates, and body-condition scores in young Thoroughbreds. Forty-eight Thoroughbred foals from three central Kentucky farms were randomly allocated to two treatment groups: an interval dose program receiving bi-monthly rotations of ...
Anthelmintics efficacy against intestinal strongyles in horses of Sardinia, Italy. Intestinal strongyles (IS) are the most important parasites of equids, due to their high prevalence worldwide, pathogenicity and the spread of drug-resistant populations. Despite the large number of horses bred in Sardinia Island, Italy, no data are available on the efficacy of anthelmintic compounds in the control of horse strongylosis. Therefore the aim of the present study was to evaluate the efficacy of five commercial anthelmintic formulations containing fenbendazole (FBZ), pyrantel (PYR), moxidectin (MOX) and two ivermectin formulations (IVM1 and IVM2) against IS in Sardinia by performin...
Estimation of infection of internal parasites in horses from different type of farms. Studies were carried out in year 2014 during the pasture period (from April to October) in Warmia and Mazury Region. Fecal samples were taken from cold- and warmblood horses from individual and agrotouristic farms with the different housing, feeding and pasture- care practices. Total of 512 horses were examined (320 mares, 170 geldings and 22 stallions). In the group of 185 horses from individual farms, 119 animals (64.3%) were infected with gastro-intestinal parasites. Among the 372 horses from agrotouristic farms 169 (51.7%) were infected with parasites. Most of the animals expelled the eggs...
Efficacy of major anthelmintics for reduction of fecal shedding of strongyle-type eggs in horses in the Mid-Atlantic region of the United States. In the last decade there have been numerous reports of anthelmintic resistant cyathostomins in many parts of the world. The objective of the present study was to evaluate the efficacy of the commercially available anthelmintics against cyathostomin egg shedding in the Mid-Atlantic region of the United States. A total of 989 horses from 67 different farms located in southeastern Pennsylvania, northern Delaware, and northeastern Maryland were treated with fenbendazole, oxibendazole, pyrantel pamoate, ivermectin, or moxidectin at their recommended dosages. Fecal egg count reduction testing was us...
Local and systemic inflammatory and immunologic reactions to cyathostomin larvicidal therapy in horses. Encysted cyathostomin larvae are ubiquitous in grazing horses. Arrested development occurs in this population and can lead to an accumulation of encysted larvae. Large numbers of tissue larvae place the horse at risk for developing larval cyathostominosis. This disease complex is caused by mass emergence of these larvae and is characterized by a generalized acute typhlocolitis and manifests itself as a profuse protein-losing watery diarrhea with a reported case-fatality rate of about 50%. Two anthelmintic formulations have a label claim for larvicidal therapy of these encysted stages; moxidect...
Economic assessment of FEC-based targeted selective drenching in horses. In the face of an increased prevalence of drug-resistant cyathostomin populations, a targeted selective treatment (TST) strategy based on Faecal Egg Counts (FECs) has been proposed as an alternative management strategy. However, associated costs may be a barrier to the uptake of this strategy. Our study aims to provide an economic assessment of FEC-based TST. FECs were determined in a Welsh pony herd thrice a year from 2010 to 2014. This database was used to explore the impact of FEC price, sampling strategy (individual or pooled) and labour-associated costs. Drug price was set at the cheapest...
A survey on parasite management by equine veterinarians highlights the need for a regulation change. In-depth knowledge of the use of anthelminthics in the field, especially by veterinarians, is required to design more sustainable parasite control strategies. Methods: An online survey was sent by e-mail to 940 equine veterinary practitioners to describe their equine practice, their awareness about parasites and the management strategies they apply. Results: Gastrointestinal parasites were generally considered (68%) as an issue of moderate importance. Drug efficacy failure was a minor or moderate issue for 47% and 48% of responders, respectively. Parasite management mostly relied on the use of...
The anthelmintic efficacy of natural plant cysteine proteinases against the equine tapeworm, Anoplocephala perfoliata in vitro. Papaya latex has been demonstrated to be an efficacious anthelmintic against murine, porcine, ovine and canine nematode parasites, and even those infecting poultry, and it has some efficacy against rodent cestodes. The active ingredients of papaya latex are known to be cysteine proteinases (CPs). The experiments described in this paper indicate that CPs in papaya latex, and also those in pineapples, are highly efficacious against the equine cestode Anoplocephala perfoliata in vitro, by causing a significant reduction in motility leading to death of the worms. The susceptibility of A. perfoliat...
Efficacy of selected anthelmintic drugs against cyathostomins in horses in the federal state of Brandenburg, Germany. Cyathostomins are currently the most common internal parasites of horses. With the intensive use of anthelmintic drugs over the past decades, resistance of cyathostomins to anthelmintics is becoming a growing problem in many countries. The aim of this study was to assess the current situation on horse farms in the German federal state of Brandenburg. A pre-selected population of horses from 24 premises that had shown a prevalence of cyathostomins higher than the average in a previous study was examined for anthelmintic efficacy. Faecal egg count reduction tests (FECRTs) were performed for iver...
Susceptibility of helminth species from horses against different chemical compounds in Brazil. By means of parasitological necropsies, the present study aimed to evaluate, in six experiments, the degree of susceptibility or resistance of different helminth species which naturally infect horses to ivermectin 0.2 mg/kg, abamectin 0.2 mg/kg, moxidectin 0.4 mg/kg, trichlorfon 35 mg/kg, ivermectin 0.2 mg/kg+praziquantel 2.5 mg/kg, abamectin 0.2 mg/kg+praziquantel 2.5 mg/kg and ivermectin 0.2 mg/kg+6.6 mg/kg pyrantel. At experimental day zero, the horses were allocated to treatment groups based on average counts of strongylid eggs per gram of feces (EPG) obtained on days -3, -2 and -1. Oxyuri...
Changes in Serum Strongylus Vulgaris-Specific Antibody Concentrations in Response to Anthelmintic Treatment of Experimentally Infected Foals. Strongylus vulgaris is the most pathogenic nematode parasite of horses. Its extensive migration in the mesenteric blood vessels can lead to life-threatening intestinal infarctions. Recent work has shown that this parasite is still identified among managed horse populations. A serum enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of migrating larvae of S. vulgaris. Previous work has documented an increase in ELISA values following larvicidal treatment with ivermectin and suggested that the target parasite antigen is primarily produced by the later larval stages. T...
Development of the larval migration inhibition test for comparative analysis of ivermectin sensitivity in cyathostomin populations. Cyathostomins are the most prevalent parasitic pathogens of equids worldwide. These nematodes have been controlled using broad-spectrum anthelmintics; however, cyathostomin resistance to each anthelmintic class has been reported and populations insensitive to more than one class are relatively commonplace. The faecal egg count reduction test (FECRT) is considered the most suitable method for screening anthelmintic sensitivity in horses, but is subject to variation and is relatively time-consuming to perform. Here, we describe a larval migration inhibition test (LMIT) to assess ivermectin (IVM)...
Resistance of gastrointestinal nematodes to the most commonly used anthelmintics in sheep, cattle and horses in Spain. The objective of this study was to evaluate the status of anthelmintic resistance (AR) in ruminants and horses in Spain. The efficacy of commonly used macrocyclic lactones (MLs) - ivermectin (IVM) and moxidectin (MOX) - was measured in sheep, cattle and horses. In addition, albendazole (ABZ) and levamisole (LEV) were evaluated in sheep and oxibendazole (OXI) and pyrantel (PYR) in horses. Efficacy was evaluated based on the difference between the arithmetic mean pre- and post-treatment faecal egg count (in cattle and horses), or compared to an untreated control group (in sheep). AR was present ...
Seroprevalence and Potential Risk Factors Associated with Neospora spp. Infection among Asymptomatic Horses in Jordan. This study aimed to determine the seroprevalence and to identify risk factors associated with Neospora spp. infection in horses in Jordan. Management related data were collected from each farm and individual horses. Sera from 227 horses from 5 of 6 climatic regions in Jordan were analyzed for the presence of antibodies to Neospora spp. by ELISA kit. The study was performed during spring of 2010. The association between seropositivity and risk factors was analyzed. A total of 7 (3%) of 227 sera had antibodies for Neospora spp. There was a significant regional difference (P=0.018) between the 5 ...
Anthelmintic resistance in equine helminth parasites – a growing issue for horse owners and veterinarians in New Zealand? There is growing concern that given the high frequency with which anthelmintics are being administered to many horses, anthelmintic resistance amongst equine helminth populations will be an increasing problem, rendering many of the currently available products unusable with little prospect of new products becoming available, at least in the near future. Worldwide, much reliance has been placed on the macrocyclic lactone (ML) group of anthelmintics, but resistance has been reported to these products as well as to the two other major anthelmintic classes used in this species, the benzimidazoles ...
An evidence-based approach to the evaluation of ethnoveterinary medicines against strongyle nematodes of equids. Cyathostomins are the most important gastrointestinal nematode infecting equids. Their effective control is currently under threat due to widespread resistance to the broad spectrum anthelmintics licenced for use in equids. In response to similar resistance issues in other helminths, there has been increasing interest in alternative control strategies, such as bioactive plant compounds derived from traditional ethnoveterinary treatments. This study used an evidence-based approach to evaluate the potential use of plant extracts from the UK and Ethiopia to treat cyathostomins. Plants were shortl...
Questionnaire study on parasite control practices on Thoroughbred and Standardbred breeding farms in New Zealand. Against a global background of increasing anthelmintic resistance in parasites, little is known about the current parasite control strategies adopted within the equine industry in New Zealand. The aim of the study was to describe and compare the current parasite management and control practices used on Thoroughbred and Standardbred stud farms in New Zealand. An online questionnaire was used to collect data on the demographics of respondents, parasite control methods, grazing management, and use of faecal egg counts. Questions regarding parasite control strategy, how often horses were dewormed,...
Cranial Mesenteric Arterial Obstruction Due To Strongylus vulgaris Larvae in a Donkey (Equus asinus). Arteritis due to Strongylus vulgaris is a well-known cause of colic in horses and donkeys. The current report describes a fatal incidence of arterial obstruction in cranial mesenteric artery caused by S. vulgaris infection in an adult donkey in which anthelmintic treatment was not regularly administered. Necropsy findings of the abdominal cavity revealed a complete cranial mesenteric arterial obstruction due to larvae of S. vulgaris, causing severe colic. To the authors' knowledge, a complete cranial mesenteric arterial obstruction due to verminous arteritis has rarely been described in horses...
Interaction between anthelmintic treatment and vaccine responses in ponies naturally infected with cyathostomins. Anthelmintics and vaccines are commonly given concurrently in routine equine management, but it is unknown to what extent an interaction between the two exists. Cyathostomins can modulate the local immune response by stimulating a type 2 helper T cell (Th2) response. In addition, anti-inflammatory effects of ivermectin have been found in rodent models. It is unknown whether these anti-inflammatory effects affect the acute phase response elicited by commonly used vaccines. This study evaluated how the acute phase inflammatory response, leukocyte expression of pro-inflammatory cytokines, and vac...