Hi All,
Welcome to topic 5 for 624EHS - Contemporary Issues in Equine Science.
This topic is all about parasite control practices. Make sure that you look at the launch PowerPoint, which has been posted in the Classroom. DL students (and others who choose this option) are required to contribute to this blog as part of their CW3 assessment. All students have from now until 11:59 pm on Friday 5th of March 2021 to contribute to this blog, to debate the issues surrounding parasite control practices within the equine sector. Ensure you can also evidence your opinions and remember that you are also required to submit a reference list (word document emailed to module leader) by 11.59 pm on Friday 5th of March 2021. You will be graded on the quality and quantity of both your blog contributions and your reference list. Remember, the point of this is to debate the issues, so you should be replying to each other's posts. I will be keeping an eye on the blog, but if you have any issues, you should email me. Please remember to register your name with your comments so that I know who has contributed with which comment. Other FT students can contribute to the blog in preparation for the in-class debate but will not be assessed on this.
Rosa
It is important that all horse owners know and understand the importance of worming correctly. There are many different worms that can put a horse at risk, the most common being bloodworms, Tapeworms, Pinworms and Stomach bots which all need different wormers to help manage the worms a horse could have (Rendle, 2014). If a horse gets worms, the horse could experience depression and a dull coat, but can also have more severe problems such as weight loss, diarrhea, colic and on the rare occasion worms can cause death (Shepherd, 2011). Giving a horse the correct amount of dosage while worming is very important for managing worming. If a horse has been under dosed, the wormer may not work, but studies have shown that horses can build up a resistance and immunity to wormers if they are exposed to it in large amounts. This can disrupt the effectiveness of the wormer as the horse's system becomes immune to it, resulting in the worms still being able to cause problems (Roslin, M. 2019). Measuring a horse's weight helps give the horse the correct dosage needed and is done by most commonly using a weighing tape, or for a more accurate result, a weigh bridge. Wormers typically have a measurement of KG on them which will give the correct dosage for the horse that is getting wormed (Talbot, 2014). Owners should do a faecal worm egg count (FWEG) each season to ensure their horse actually needs a wormer, to prevent immunity. Results from this strategy are shown in the number of eggs per gram (epg). By doing these tests on a regular basis throughout the year, for an adult horse, this should be done at least four times a year (Rinaldi, 2019). This will of course, only allow the horse a wormer when needed, but a WEC normally requires a form of payment, as it is normally done by a vet in a lab. Because of this, owners may dismiss WEC as if the horse is needing a wormer, it is adding more money each time, but then if the horse doesn't need a wormer, money is saved. It also may be hard to get a dropping from a horse that lives out with other horses, as it is hard to tell who is who.
ReplyDeleteTia
Following on from some of the points Tia has made, an ever increasing incidence of anti-parasitic drug resistance in animals is urgently pushing equestrians (and farmers) to design sustainable parasite control strategies which can be applied both on and off the host. Kumar et al (2012) explains how a majorty of the worlds livestock are kept on grazing based production which means they are at risk of high exposure to parasites. World wide reports have suggested that this exposure to parasites, leads to parasitic disease (adversely affects health, weight loss/gain, feed conversion efficiency & reproduction) which inflicts severe economic losses on the livestock industry. Although pasture management is a large part of prevention, it is also important that housing and nutrition are effectivley managed. Horses with good living conditions resist or tolerate better against internal parasites compared to those who unfortunatley have poor living conditions. Stabling must be well ventilated and lighted to maintain required humidity and air circulation, a lack of these variables leads to accelerated growth of parasite populations. Faecal matter should be removed regularly, and water buckets/drinkers should be cleaned often. Kumar et al (2012) also highlights the importance of diet in building up a tolerance to parasites. Vitamins A, D and B are essential in developing an immunity and minerals such as zinc and iron are essential for the the proper functioning of the immune system. Finally, in terms of management, ensuring equines are grazing on well managed pastures will also help to prevent parasitic disease. Rotating and resting any paddocks/fields, grazing by age group (susceptibility varies between age groups), multispecies grazing (often parasites can not be passed between species, therefore rotating the type of animal will break down the parasites life cycle), or zero grazing (if absolutley necessary) will have an impact on the severity of any parasitic cases that may occur.
DeleteAbbie
In comparing the use of parasite control preferences between Germany, Austria, Denmark, the Netherlands, and the US, Becher et al (2018) found Denmark to have significantly different strategies, making use of the coprological analyses and treating substantially less than respondents from the other countries. Germany and Austria have implemented the prescription only medication for 30-40 years implemented by law which is a drastic comparison to the USA and UK where the over counter purchase of anthelmintics is allowed. German legislation allows for a more herd based approach compared to Denmark which veterinary authorities require individual diagnostics. Treating less with the anthelmintic products and making more use of faecal egg counts (FEC) as monitoring tools (Becher et al. 2018).
ReplyDeleteThe marked development of anthelmintic resistance and a general scarcity of new anthelmintic drug classes have led parasitologists to abandon the classical approach of dosing animals with constant intervals year round. Instead, it is recommended to generally reduce the usage of anthelmintic drugs and increase diagnostic activities (Kaplan 2013). However, it has been speculated that the willingness to pay may influence the use of FECs and this assumption is supported by the Becher et al (2018) study.
Leanne
There are many preventative methods that can be used to avoid a horse getting worms as well as correct treatment methods and parasite control. Pasture management will reduce the likelihood of horses getting worms, having too many horses in one paddock can increase the possibility of a high worm egg count, this is because there are more horses living in one area and more dung being produced. By keeping to the ‘one horse one acre’ rule, put in place by the animal welfare act, 2006 over populating a paddock should not be occurring (GovUK, 2021) Removing dung from a horses field should be done on a regular basis to ensure the pasture is as clean as possible as well as managing the egg worm count. By picking up droppings at least once-twice a week, the worm eggs will be more unlikely to make their way to the grass for the horses to consume (Batson, 2012). Another way of managing a pasture is by cross grazing horses with other farm animals, such as sheep and cattle. These species of animals will then consume any worms on the grazing land (Ben, 2012). Worms cannot live efficiently in these species so they eventually die, reducing the worm egg count.
DeleteInterestingly, although effective management of variables such as pasture, housing and nutrition are vital in the prevention of parasitic disease Kumar et al (2012) discusses the possibility of using genetics in the war against parasites. There are certain breeds which have a higher resistance to parasites than others, selective breeding could provide us with the opportunity to breed horses which do not require preventative treatments throughout the year. The concern for anti-parasitic drug resistance in animals is growing, horse owners are encouraged to consistently mix up their wormers so they continue to work, and what with there only being four main classes of anthelmintics there is not a lot of room to play with (Rendle et al, 2019). There have also been studies into the effectiveness of biological control and the positive impact that it can have on reducing parasites in the equid population. Arias et al (2013) carried out a study which followed captive European and African donkeys, and zebras as there were put through two trials, the first of which consisted on chemotherapy only and the second trial consisted of chemotherapy and the administration of chlamydospores of the nematophagous fungus Arthrobotrys. Results were gathered through faecal worm egg counts, and although more research is needed to determine the full effectivenessof the method, this preliminary study demonstrates how the incorporation of chlamydospores of nematophagous fungus, as A flagrans appears highly promising for reduction of the infective stages of the strongyles.
DeleteAbbie
BHS (2020) suggest cross grazing with cattle and sheep as a method of breaking the parasite life cycle. Sheep and cattle will ingest the equine parasites and halt their lifecycle with no adverse effect on them.
DeleteDung removal from pasture does play a crucial role in reducing infection in the herd environment. As found in this study by Tzelos et al. (2019), 75% of respondents say they removed dung, similar to, Easton et al. (2016) which shows 80% of people stating they do this on a regular basis. These are the highest levels of uptake reported and offer hope that the knowledge of the benefits of dung removal are reaching the target audience. Some potential reasons which horse owners may be unwilling to participate in dung removal are, the gradient of the lane, increased horse numbers, the labour associated with the task and limited staff resources and or lack of knowledge (Tzelos et al. 2019). Another benefit of removing droppings from pasture is that it stops the development of unpalatable latrine areas (BHS 2020).
Ectoparasite infections are a growing concern to both horse owners and veterinarians. Health and welfare issues caused by parasites such as mites, lice, ticks, and flies can lead to health conditions, reduced performance, and loss of condition. Additional risk includes the parasites functioning as vectors for pathogens, some of which are zoonotic in nature, leading to potential severe implications on both equine and human health (Payne et al. 2017; Karasek et al. 2020). Ectoparasites can cause diseases such as babesiosis, anaplasmosis, theileriosis and heart water. Increased awareness of the risk of zoonotic infections being spread by horses is needed for adequate control and disease prevention. Many of the tick and tick borne diseases usually occur in specific geographical areas with globalization and climate change and their range may be expanded and can even be spread intercontinentally.
ReplyDeleteTreatment strategies can include topical and systemic drug application and treatment of the environment. There are only a small number of products which are approved for treatment of ectoparasites in horses (Payne et al. 2017).
The following studies found high prevalence’s in both domesticated horses in Cameroon and feral horses in Turkey.
Karasek et al. (2020) found three species of hard ticks in over 800 horses which participated in the study Boophilus decoloratus, amblyomma hebraeum, hyalomma rufipes and one species of biting lice Bovicola equi. This study found no difference in the horses age, sex, or colour of the horse and all horses in the study had a high parasite prevalence.
Dik et al. (2020) in a similar study to above, however on feral horses in turkey not domesticated found that 97.2% of horses were infested with ectoparasites. They found five species, including, B. equi, Hippobosca equina, Ha. Parva, Hy. Excavatum, Dermacentor marginatus.
These findings suggest that more is needed to control the spread of infection throughout the world equine population in order to reduce the risk of health problems for both the horse and human.
There are many ectoparasites that affect equids (lice, flies, mites, midges and mosquitoes) and can pose a threat to a horse’s health and welfare. Ectoparasites can cause a decrease in a horse’s performance, loss of condition and irritation (Baynes et al, 2020). Some parasites are more dangerous than others, some can act as vectors for other pathogens that are zoonotic and can have a severe impact on both horse and human health (Baynes et al, 2020).
DeleteSome treatments have been made to fight against ectoparasites that include systemic and topical drug application and treatments to the environment that they are living in. However, globally there are very little approved products to help horses. The lack of approved medication has raised concerns with the efficacy and safety when being used on horses. Minimal knowledge on dermatopharmacokinetics proves to make it difficult when creating safe and systemically applied drugs or products for horses (Baynes et al, 2020). There’s some evidence that exists that proves the efficacy of certain compounds to fight against ectoparasites, however more research is needed with pharmacokinetic/pharmacodynamic.
Dermatopharmacokinetics has been studied further and it has been reported that the effects on distribution of drugs through the skin and how skin preparation, vehicle and site have had an effect on the horse (Cross and Mills, 2006a, 2006b, 2007; Mills, 2007). Using this evidence and identifying the chemical characteristics of the compounds they were able to create safe treatment modalities. However, these are not directly to treat ectoparasites. The evidence created is with similar pharmacokinetic characteristics distributing drugs over and through equine skin.
DeleteEven though Worms are the most well known parasite, ectoparasites can also make a large impact on a horse's health and wellbeing. Ectoparasites are found on the outside of an animal's body which can damage the animal's soft tissue, such as ticks, mites and fleas (Wilson, 2014). A horse that encounters any of these parasites, will probably have an effect on the horses overall welfare as ectoparasites can irritate the horses skin, cause lack of condition, decrease food and forage intake and cause infections. A study conducted by Wilson in 2014, evaluated prevalence of infestation of ectoparasites of 894 horses in the western highlands of Cameroon. This test discovered that 99.48% were infested by ectoparasites, concluding that these parasites are very common, even if some cases are more severe than others. Because of this it is crucial for horse owners to be checking their horses skin and coat regularly for these parasites. Like endoparasites, there are many ways to treat a horse with skin parasites to prevent irritation and increase in harm to the horse's skin.
DeleteCyathostomins, commonly known as small strongyles are found in horses throughout the world and represent the main parasite of concern for modern anthelmintic treatment programmes. In large numbers they can cause symptoms such as sudden onset diarrhoea, weight loss, subcutaneous edema, fever and colic – with 50% mortality rate. (Cain et al. 2020)
ReplyDeleteSurveillance programmes such as FECs are helping reduce the number of anthelmintic drugs used in the equine population. Only the horses contributing the highest number of eggs to pasture are treated.
The American Association of Equine Practitioners (AAEP) currently recommends two FEC methods for determining the number of strongyle parasite eggs in feces: a modified McMaster and a modified Wisconsin technique. (Went et al. 2018). Faecal egg counts are important tools in equine parasite control, they can be used to evaluate anthelmintic treatment efficiency and to identify high strongylid egg sheders in need of treatment. While both useful and important strongylid fecs are also subject to confusion, there are many techniques and modifications, and it is difficult to discern what advantages these may offer relative to each other. However, the most recent methods of FEC which are automated are significantly and 2 -3 times more precise than traditional methods (Cain et al. 2020).
Additional research into the areas such as egg loss, analyst variability at the counting step is necessary to fully gauge the impact that automated FEC systems will have on equine parasitology.
There have been no new anthelmintics introduced in the UK livestock market for the past 32 years. Consequently, resistance is redefining how parasite control should be practiced and how anthelmintics should be used. It became common practice to treat (healthy) horses with anthelmintic drugs every 2 months, year round (Kaplan 2013).
ReplyDeleteHorse owners and livestock producers could buy anthelmintics in the feed store—and, later, over the Internet—much more cheaply than through a veterinarian, and pharmaceutical companies marketed their drugs directly to livestock producers and horse owners, so veterinarians became less and less involved in parasite-control decisions (Kaplan 2013)
Anthelmintic resistance is now rampant and only one drug class out of three available for horses, the macrocyclic lactones are still effective against cyathostomins albeit with emerging resistance (Cain et al. 2020).
The reliance on ivermectin and moxidectin for equine nematode control in the last 30 years, resistance, measured as a reduction in FEC of less than 90-95% at 14-17 days treatment has been reported infrequently. Nevertheless, there have now been several reports of reduced strongyle egg ERP after ivermectin or moxidectin administration in several countries.
Resistance to the earlier registered anthelmintics has been reported in many populations across the world, fenbendazole resistance in cyathostomins is virtually ubiquitous in many regions and should not be recommended to control this infection in these areas (Matthews 2014).
To examine the infestation of ectoparasites in Cameroon 894 horses (367 males and 527 females) were randomly selected between 1-7 years old (Mbafor et el, 2017). These horses were examined externally once a week for 36 weeks and lived out grazing in the pasture with each other and other livestock animals. Ticks were collected during the parasitic phase. The hosts were restrained and stood on a 2 x 4 m white bed sheet where they were groomed. Any ticks that fell on to the bed sheet were collected at the end in plastic vials containing 70% ethanol and sent off after being labelled to the lab (Mbafor et el, 2017).
ReplyDeleteThree species of hard ticks where identified (Boophilus decoloratus, Amblyomma hebraeum and Hyalomma rufipes) and one biting lice (Bovicola equi). All four of these ectoparasites were found in all age groups except for lice in ages 2, 6 and 7 years. The highest found was B. decoloratus (69.8%) in all age groups of horses, followed by A. habraeum (17.6%) and H. rufipes (10.8%) who preferred older horses ages 6 and 7; whilst B. equi (8%) was found on younger horses between ages 3 and 4 (Mbafor et al, 2017).
Mares were infested more with B. decoloratus (83.2%) and B. equi (4.4%), whereas geldings had a higher prevalence of A. habraeum (26.6%) and H. rufipes (17.4%).
Coat colour also had an effect on where the parasites were located. Boophilus decoloratus showed higher in bay horses (71.69%) whilst Amblyomma showed higher in black horses (24.14%). H. rufipes (16.94%) was highest on grey horses. Bovicola equi were found in both grey (4.71%) and bay (2.42%) horses respectively.
This study has identified that there is a significant threat that parasites pose on horse health regardless of age, sex and colour. B. decoloratus was found to be the highest in all age groups (69.8%), mares (83.2%) and bay horses (71.69%). This tick is more prominent in large mammals, especially horses and cattle, in Neotropical, Afrotropical and Australian regions of the world (Abebaw, 2004). Another component to the higher amount of ticks found in this study was due to the fact the horses were living out with other livestock that have been living free range from the time they’d been brought from markets (Mbafor et al, 2017). This makes them the perfect potential host for these parasites found where they are able to attach and live out their short life span where they will create more offspring.
Another factor would be poor horse management of the pastures being used in the study. The pastures weren’t being treated or managed and therefore exposed the horses to infestation. Results also showed that there has been no preventative or curative treatment used on the horses beforehand. Without the help of proper horse management and preventative measures, horses in this study had a high provenance of ectoparasites living on and underneath their skin feeding on their body to survive. With the use of correct management these horses would have been less likely to gain these parasites and is overall against the Animal Welfare Act 2006 which states that the animal is protected from pain, suffering, injury and disease and under section 9(2)(a) of the act (Department for Environment Food & Rural Affairs, 2017).
In regards to ectoparasites, Horse breeds can contribute to the likelihood of a horse being affected by ectoparasites due to thicker coats or extra hair, such as horses with feathers or cushings (Bergvall, 2005). Even though cob-like breeds have a higher likelihood of getting these skin parasites, it is important that all horse owners help prevent an ectoparasite encounter and use the correct treatment needed if their horse does get them or is prone to getting them. Starting control before the midge season is very important for horse owners to know to try and prevent horses getting skin diseases when it's too late. It is advised by ‘Veterinary practice, 2020’ to stable vulnerable horses during dawn and dusk when midge activity is at its greatest, as well as turning horses out in large pastures or higher ground to keep away from potential midge infested areas, such as woodland and forests. Using fly rugs, fly masks and fly spray throughout the summer will also help protect a horse's skin and prevent midge making contact, as well as fly bites and other ectoparasites. Another easy preventative method that all horse owners should do is regular grooming, so owners can be checking the horses skin regularly for bumps, bites, irritation or infection (Wilson, 2014).
DeleteEctoparasites live on, burrow and puncture under the skin to feed and shelter on the living animal (Colebrook and Wall, 2004). However long they live on or under the skin they will shed a secrete or excrete antigen that is able to stimulate inflammation, innate and adapt immune responses (Aspock and Krenn, 2012). The largest group of ectoparasites that affect the immune system are blood feeding arthropods because of the antigenic components present in their saliva (Wilson, 2014). To fight against these sort of ectoparasites, the hosts have a counteract strategy that include behavioural responses, inflammation, haemostasis and immunity (Wilson, 2014).
ReplyDeleteThey can cause diseases anaplasmosis, babesiosis, heart water and theleriosis. Humans are also affected and they can transmit diseases like Lyme disease, Rocky Mountain spotted fever and emerging infectious diseases like Crimean–Congo haemorrhagic fever (Mbafor et al, 2017). Zoonotic infectious are mostly common amongst infants, elderly, during pregnancy, people with immune problems, zoo-workers, veterinary and other vet workers (John and Stephen, 2003). Therefore, an increase in control measures needs to be put in place to stop and prevent the spread from horses (Anne and Gary, 2006).
Relating back to welfare issues and implcations caused by parasites, it is safe to say that a lack of knowledge and understanding could lead to the growth of a parasite population. Horseman et al (2016) comment on how the biggest cause for welfare issues within the equine industry is purely down to a lack of knowledge and experience. Many horses are over/underweight, on the wrong diet, shod wrong etc. simply because novice owners are not aware of the correct methods or better yet, which method works best for their horse. As Kumar et al (2012) mentioned, effective management of housing, grazing and nutrition all play such an important part of keeping a horse healthy, if an equestrian is not aware of the importance of these factors, or even the risks that come with paratites and parasitic disease, it is likely they will experience it for themsleves before fully realising the impact. The future of parasitic prevention lies not only with the development of a new treatment (one more to work into the rotation - one more to become immune to), genetic and biological influences, but also the education of as many equestrians as possible. knowledge is power, and the power to prevent parasites is one all livestock handlers could benefit massivley from.
ReplyDeleteAbbie
Abbie
A survey undertaken by Tzelos et al (2019) shows that horse owners are becoming more knowledgeable regarding the issues aligned with anthelmintic resistance and parasite control. The objective of this survey was to assess if there was continued improvement in the uptake of evidence based parasite control practices as there have been no UK based survey related research in this field since 2014.
DeleteThe owners that participated in this study were split into two categories. Those who treat intermittently and those who treat on a targeted approach.
The findings show that people who have a targeted approach are more knowledgeable about the parasite for which they are treating and are also more concerned with the implications regarding anthelmintic resistance. Overall, over 75% of people were not aware of the status of anthelmintic resistance at their property. The main source of purchase was over the internet and there is a link to show the people seeking advice from internet retailers are more likely to be intermittent treatment. Seeking advice online is not ideal, the owners were given little to no professional advice before purchasing wormers online.
An area where people lacked knowledge was foal treatment, this could be due to the average horse owner not having experience in breeding or foal management, however those that did said they gave the same wormer to a foal they would an adult horse they just changed the dose.
Limitations to this study include the inevitable bias of an online survey reaching only 0.15% of the horse owning population in the UK currently (BETA 2015) And a social bias in which respondents will answer in a way that they feel is favourable to others (Easton et al. 2016; Rose Vineer et al. 2017; Tzelos et al. 2019)
Tapeworm (Anoplocephalid cestode) occurs worldwide in horses and has been identified as a potential cause of a variety of different forms of colic. There are three different types of tapeworm: Anoplocephala perfoliata, A. magna and Anoplocephaloides mamillana (formerly known as Paranoplocephala mamillana) (Nielsen, 2015). A. Perfoliata is the most common out of all of them.
ReplyDeleteIt has now been identified that there are a variety of diagnostic techniques that can diagnose tapeworm. The most traditional technique is coprological analysis which is aimed at identifying tapeworm eggs in the intestine. This has been attempted through sedation, faecal egg counting and qualitative flotation, however the technique has been found challenging because of egg shredding and the distribution of the eggs in the faeces (Nielsen, 2015). The egg counting technique is more regularly used and is sent to a lab in order for them to identify the amount of eggs present. Polymerase chain reaction (PCR) has also been developed to detect A. Perfoliata DNA in faeces by using a high diagnostic sensitivity, however it has been identified that the egg counting technique has a higher performance (Campigli et al 2008). In order for this method to be used further research and modification needs to be made.
Two treatments are available for tapeworm: pyrantel pamoate and praziquantel (Nielsen, 2015). These come as pastes in wormers and have been proven to reduce activity against A. Perfoliata by 80% when given 6.6 mg base/kg (Collins et al, 1989). However the dosage has been boosted up to 13.2 mg base/kg because it has been shown that by increasing the dosage it increased the efficacy against A. Perfoliata by 95% (Dascanio et al, 2006; Eckblad et al, 2006).
Praziquantel has made in the 1990s which includes a combination of ivermectin or moxidectin however a praziquantel only product is also available (Nielsen, 2015). This wormer is given at 1.0 mg/kg bwt dose rate because of the higher efficacy against all three parasite species (Marley et al, 2007; Barutzki et al, 2007).
Faecal egg samples get collected and sent back in ziplock plastic bags to the laboratory where they get stored at 4 degrees celsius until they get analysed (Lester et al, 2013). The samples usually get tested as soon as possible whilst the faeces and parasites are still fresh. It is a complex method that requires a Poisson counting error process for each sample and continuous distribution of means between the samples (Denwood et al, 2012). A McMaster method is used to quantify faecal egg counting which was originally created for sheep, before it was proven to be effective for horses (Hunter and Quenouille, 1952; McKenna, 1981; Cavill et al, 2005). Other techniques were also made to rival the McMaster method, however all had a lower efficacy rate.
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