History of Legislation

The United Kingdom first implemented laws protecting animals in the nineteenth century, though it was not until the 1960s when public awareness increased, that an interest in animal welfare grew, in turn producing many changes resulting in improved conditions for animals of many species. In 1965 the Brambell committee produced a report of recommendations for the United Kingdom’s government, which was developed by the Farm Animal Welfare Council. A set of minimum standards for farm animals and intensive husbandry systems was introduced to define the physical and mental wellbeing of animals [1]. These were known as the ‘FIVE FREEDOMS’ [2].

Although originally developed for farm animals these ‘five freedoms’, now more correctly referred to as ‘needs’ were then recognised by the Animal Welfare Act 2006 after an overhaul of welfare legislation, replacing many outdated pieces of welfare legislation. This Act places a duty of care on owners to ensure their animal’s welfare needs are met, gives more powers to those enforcing the legislation and allows tougher penalties [3].

Animal owners must always aim to provide the five ‘needs’ to their animals. The five welfare needs are as follows [3]:

• The need for a suitable diet: access to fresh water and diet to maintain health and vigour.
  
• The need for a suitable environment: providing an appropriate environment to include a shelter and a comfortable resting area.
  
• The need to be protected from pain, suffering, injury and disease: prevention of pain, injury or disease. If not possible, rapid diagnosis and treatment.
  
• The need to exhibit normal behaviour: by providing facilities with sufficient space and stimulation.
  
• The need to be housed with, or apart from, other animals: providing opportunities to interact with their own species where appropriate.

There must be some flexibility, especially in the provision of veterinary care where these needs cannot always be met. There may be occasions where food may need to be withheld, or normal behaviour may not be possible and where turnout cannot be allowed, but RVNs should seek to minimise these restrictions and provide alternatives where possible, to minimise the impact on the physical and mental wellbeing of the equine patients in their care.

The Animal Welfare Act is the legislation that is used when it is believed there are shortfalls in welfare standards. Where there are clear breaches to the Act an improvement notice can be served if an animal’s needs are not met based on the five needs. This ‘notice’ outlines the steps an owner must take to meet their animal’s needs, within a given time period, this is to prevent any suffering to that animal. If the improvement notice is not adhered to, steps can be taken before any suffering occurs. This may involve removal of animals and subsequent bans to prevent ownership of animals for a length of time, may be served by the courts [3].

The Animal Welfare (Sentencing) Bill introduced in April 2021 has increased the maximum penalty for animal cruelty in England to five years in prison and unlimited fines [4].

The Five Domains Model of Animal Welfare was updated in 2020 and is becoming increasingly popular as a tool to assess the welfare of animals. This model includes a specific evaluation of the mental state of the animal and acknowledges the role that emotions may have to play in overall behaviour and welfare. For more information, please refer to the Futher Reading section at the end of this chapter.

Codes of Practice

The Department for Environment, Food and Rural Affairs (DEFRA) have produced Codes of Practice for dogs, cats and equines. These Codes interpret the five ‘needs’ into clear and constructive advice to ensure an animal’s requirements are met. They summarise the legal responsibilities of the Act and provide guidance to owners on providing appropriate species‐specific care [5, 6].

The DEFRA Code has then been further interpreted for the equine species by the National Equine Welfare Council who published their Equine Industry Welfare Guidelines Compendium 3rd edition in 2009. This aims to serve as a reference document for all activities relating to horses and is something that all those involved in the provision of care to horses should be aware of [7].

These texts are a good place to signpost owners so they can ensure they are meeting all the required welfare needs for their animals.

Other Animal Welfare Legislation

Animal Welfare Charities

Animal charities carry out vital work, increasing public awareness of welfare needs and providing care to animals in need. Individual charities each have a code of conduct which outlines their aims and objectives.

Stable Sizes

The BHS minimum stable size recommendations for horses are as follows [6]:

• Large horses (17 hh+): 3.65 m × 4.25 m (12 ft × 14 ft)
  
• Horses: 3.65 m × 3.65 m (12 ft × 12 ft)
  
• Large ponies (13.2 hh+): 3.05 m × 3.65 m (10 ft × 12 ft)
  
• Ponies: 3.05 m × 3.05 m (10 ft × 10 ft)
  
• Foaling box (horse): 4.25 m × 4.25 m (14 ft × 14 ft)

These sizes should enable a horse or pony to act as naturally as physically possible, to lie down and move around the stable if permitted to gain access to hay, feed and water. The foaling box should allow enough space for the mare and the foal at foot.

The Donkey Sanctuary minimum stable size recommendations for donkeys are as follows [6]:

• Mules: 3.65 m × 3.65 m (12 ft × 12 ft)
  
• Large donkeys: 3.05 m × 3.65 m (10 ft × 12 ft)
  
• Donkeys: 3.05 m × 3.05 m (10 ft × 10 ft)
  
• Average sized donkeys kept in pair: 9 m² (100 ft²) of covered space.

Larger donkeys and mules will need more space, equivalent to that recommended for similar sized ponies and horses [6]. Please see Chapter 16 for more information about donkeys.

Horses are social animals and are generally happier and calmer if they can see other horses. Although it is not advisable to mix horses and ponies in the clinical environment, enabling them to look out over the stable doors will assist in their well‐being while in the practice or hospital. Some stable doors may need adapting for Shetland ponies and donkeys so they can see over the top (Figure 5.1). Some stable doors can house a top grill if needed. Isolation facilities should be available for infectious patients (see Chapter 6).

Stable design is an important consideration. The four main types are:

• Stalls
  
• Loose boxes
  
• Barns
  
• Barn and loose box combination [30].

All stable design types have advantages and disadvantages. It is important to select the design that will work best for the type of yard being built. Building materials are also an important consideration. Wood is traditionally used as it is relatively cheap, however it can be damaged easily and can also be chewed. Brick is more expensive but is stronger and easier to disinfect. Detailed information on stable design is beyond the scope of this chapter. For further information please see the ‘Further Reading’ section at the end of this chapter.

Fixtures and Fittings

Some fittings are required for all stables however stables in an equine practice or hospital will require some more specific fittings and equipment, which are also discussed below. Care should be taken to ensure that all fittings are secure and placed in an area that is convenient for staff but will not endanger the horse:

• Hooks – are required on the top and the bottom of the stable doors to hold them open and prevent them from slamming which will frighten the horses.
  
• Bolts – on both doors – one on the top door and two on the lower door. A kick bolt is advised on the lower door for extra security as some horses learn to open the top bolt.
  
• Metal strips – are required on the horizontal part of the lower door to prevent the horse from chewing the wood.
  
• Tying rings – should be placed at the front of the stable at the horse’s eye‐level.
  
• Automatic water bowls – are not usually used in an equine practice or hospital. While they do save on labour, the main disadvantage is that it is not possible to monitor how much the horse is drinking [30]. This is not ideal for RVNs when monitoring sick patients. Usually, a large water bucket is supplied as horses will drink approximately 20–40 l of water per day under normal circumstances [30]. Water should be changed frequently as it will absorb ammonia from the environment. The water bucket should be emptied and disinfected at least once daily for every patient.
  
• Feed troughs and mangers – may be made out of concrete, wood, or plastic. These fittings are useful for patients that cannot have a haynet such as foals and patients with eye ulcers. Feed troughs and mangers must be placed high enough for the horse to feed comfortably, but not so high that the horse cannot reach the food. Containers must be cleaned out and disinfected regularly to reduce contamination [30].
  
• Hay racks and haynets – hay racks and haynets keep forage in one place, but do not mimic the natural feeding posture of the horse. Ideally, horses suffering with sinus or spinal conditions would be fed from the floor. Haynets must be tied high enough to avoid patients getting their feet caught if they were to paw at the haynet.
  
• Feed buckets – are suitable for use in an equine practice or hospital, as they are easy to clean, and prove to be less of a fomite than mangers. Feed buckets should be placed on the floor to allow for a more natural feeding position for the horse. Door buckets can be beneficial in some patients that need to feed from a raised surface, for example, following dorsal spinous process removal.
  
• Fluid hangers – are hooks attached to the celling for suspending fluid bags for intravenous (IV) administration and other medications. Ideally, an overhead pulley system is used to raise and lower the fluids when the bags need changing. A spiral giving set allows the horse to move freely around the stable [30].
  
• Door grills – These are used to prevent the horse from being able to get their head over the stable door. These are used for patients with indwelling IV catheters. As the jugular vein is most commonly used for IV catheters in horses, the grill is used to prevent the horse from rubbing the catheter on the door and/or pulling it out.

Bedding

Bedding is used to provide warmth and comfort to the horse. A bank of bedding can be built up around the edge of the stable to reduce draughts, provide comfort and to help prevent the horse getting cast (stuck against the wall). The ideal bedding material would have the following properties [30]:

• Warm
  
• Absorbent
  
• Soft
  
• Easily managed
  
• Nontoxic
  
• Dust/damp free
  
• Readily available
  
• Easily disposable [30]

Table 5.1 shows the types of bedding available for equine patients, and the advantages and disadvantages associated with each.

Utilities

There should be utilities within close proximity of the stables to include hot and cold running water and an electricity supply. This would facilitate clinical treatments and assessments that need to be carried should the horse be unable to leave the stable. This is also beneficial when disinfecting the stable after each inpatient. The electricity supply must be inaccessible to horses, and any sinks must be earthed to reduce the risk of electric shocks or electrocution should a horse interfere with them. The need for hot running water is to facilitate good hygiene practices both for staff and the cleansing of patient receptacles and stable tools.

Fire Safety

Fires will also be of high risk in the stable environment. A fire evacuation plan must be implemented. The premises should be designed to incorporate the fire safety recommendations set out in the Communities and Local Government’s ‘Fire Safety Risk Assessment – Animal Premises and Stables’. Advice should be sought from the local Fire Prevention Officer in relation to statutory requirements. Highly flammable liquid material or combustible material should not be stored in or close to stables where horses are housed. Smoking in stable areas should be prohibited [6].

Ventilation

Ventilation is important to avoid draughts at ground level, which can cause a chill, but maintain a through flow of air to prevent a build‐up of bacteria and reduce the transmission of airborne infection [30]. There are two types of ventilation:

• Passive ventilation:
  
  
  
  • Can be achieved by keeping the top door of the stable open to allow air to pass through and up into the apex of the roof.
    
  • Air vents allow the air to pass out and fresh air is then drawn in through the door, maintaining a cycle.
    
  • The heat from the horse rises upwards and further encourages this cycle.
    
  • This is called the stack effect.
    
  • Windows should be located on the same side as the door to prevent through draughts but provide light.
    
  • They should be hinged at the bottom and open outwards. There should be a wire mesh or iron bars covering the glass to prevent the horse from injuring themselves on the glass.
    
  • The glass itself should be wired safety glass [30].
  
  
• Active ventilation:
  
  
  
  • Mechanically pulls air into and/or out of the stable, using an extractor or air‐conditioning system [30].
    
  • Due to the expense of installing active ventilation for stables, it is very rarely seen in equine accommodation.

Lighting

This may be natural or artificial. Natural lighting is achieved by installing windows, skylights and leaving the top half of the stable door open. To ensure that owners and staff can see adequately, some form of artificial lighting must be available [30]. The most common form of artificial lighting is a fluorescent strip light attached to the eaves of the roof. Hanging light bulbs are not ideal as the horse may be able to reach them. Light switches should be placed outside the stable and protected from moisture with a waterproof cover. All cables inside or outside the stable should have sufficient waterproof coverings [30].

Adverse Reactions

Administering a vaccine, which is a foreign substance, into the body carries a risk of an allergic reaction. Owners should be made aware that an allergic reaction may occur, and they should be advised to report this to the vet if this is observed. Symptoms can range from mild lethargy to severe shock and may include:

• Swelling of the injections site
  
• Muscle soreness at the injection site
  
• Urticaria
  
• Diarrhoea
  
• Depression
  
• Ataxia
  
• Shivering
  
• Collapse

Non‐steroidal anti‐inflammatory drugs (NSAIDs) are the most common treatment given although, steroids and supportive therapy may be given for more severe reactions. The reaction should be noted on the patient’s clinical records. The reaction should be reported to the Veterinary Medicines Directorate (VMD) via the suspected adverse reaction surveillance scheme (SARSS). See Chapter 9 for further information. A different type of vaccine should be given in future [38].

Endoparasites

There are numerous types of endoparasites (internal parasites) that use the horse as a host during their lifecycle (Table 5.4). Most horses acquire an endoparasite burden from the pasture they graze. Eggs passed in the faeces hatch into L3 stage larvae on the pasture which the horse will then ingest. These larvae then enter the intestinal mucosa where they eventually develop into fourth stage larvae, moult to adults which in turn then lay eggs which are passed out in the faeces thus completing the cycle. The degree of damage done to the horse depends on the type of worm, its lifecycle (whether it remains inside the gut or migrates around the body), the number of worms present, and the health and immune status of the horse (Figures 5.3 and 5.4).

Management of Endoparasites

Pasture Management

Pasture management strategies can be implemented to try to break the lifecycle of the worm burden. These include techniques such as the following:

• Poo picking – removing the faeces daily from the pasture will significantly reduce the amount of worm eggs being ingested, although this is not always possible due to time and weather constraints.
  
• Chain harrowing – this is not considered effective as a pasture management strategy as it actively spreads worm eggs and larvae around the pasture.
  
• Resting the pasture – from late summer until the following spring. This aids worm control because most of the larvae on the pasture will die‐off over the winter. However, certain species such as large roundworm eggs, can survive in the soil for years.
  
• Cross grazing equids with other species – such as sheep. This is an excellent way to reduce the worm burden on the pasture. Sheep are not affected by equine endoparasites and are known as ‘biological hoovers’ for the land.
  
• Reducing the stocking density of equids on the land. Overstocking results in pasture with a high concentration of faeces and therefore great potential to infect the grazing animal if these faeces contain parasites or eggs.

Worming Strategies

There are three main strategies which are employed when considering the administration of anthelmintics to equine patients.

Interval Dosing

This is the administration of a specific drug at the yearly time interval recommended by the wormer manufacturer [40]. Interval dosing encourages increased use of anthelmintics at lower risk times, such as winter periods, when horses spend increased amounts of time stabled. This is expensive and often unnecessary. Also, many horse owners use anthelmintics at inappropriate intervals. The main disadvantage of this strategy is that horses may be dosed unnecessarily which may encourage the development of resistance [40]. Resistance occurs when parasites become tolerant to a drug used to kill them. It is an inherited trait that develops in response to selection pressure favouring survival of worms with the genetic ability to survive chemotherapy [39]. For this reason, it is essential that horses are dosed accurately according to bodyweight. Using too low a dose of wormer may speed up the development of resistance. On the other hand, frequent, unnecessary worming may also increase the potential for the development of resistance.

Disease	Vaccine protocol	Special warnings for each target species
Equine influenza	Primary course: From six months of age – 1 × 1 ml dose by intramuscular injection. Second dose four weeks later. Third dose (revaccination dose) five months after primary course. This revaccination results in immunity to equine influenza lasting at least 12 months Yearly boostera [32]	Foals should not be vaccinated before the age of six months, especially when born to mares that were revaccinated in the last two months of gestation, because of possible interference by maternally derived antibodies Vaccinate healthy animals only [32]
Clostridium tetani	Primary course: From six months of age – 1 × 1 ml dose by intramuscular injection. Second dose four weeks later The first revaccination is given not later than 17 months after the primary course. Thereafter, a maximum interval of two years is recommended [33].	Foals should not be vaccinated before the age of six months, especially when born to mares that were revaccinated in the last two months of gestation, because of possible interference by maternally derived antibodies Vaccinate healthy animals only [33]
Equine influenza and clostridium tetani (combination vaccine)	Influenza: Primary vaccination course: From six months of age – 1 × 1 ml dose by intramuscular injection. Second dose four weeks later. Third dose (revaccination dose) five months after primary course. This revaccination results in immunity to equine influenza lasting at least 12 months The second revaccination is given 12 months after the first revaccination The alternate use, at 12 months interval of a suitable vaccine against equine influenza, containing the strains A/equine‐2/South Africa/4/03 and A/equine‐2/Newmarket‐2/93, is recommended to maintain immunity levels for the influenza component* Tetanus: The first revaccination is given no later than 17 months after the primary vaccination course Thereafter, a maximum interval of two years is recommended Other comments: In case of increased infection risk or insufficient colostrum intake, an additional initial injection can be given at the age of four months, followed by the full vaccination programme (primary vaccination course at six months of age and four weeks later) [34].	Foals should not be vaccinated before the age of six months, especially when born to mares that were revaccinated in the last two months of gestation, because of possible interference by maternally derived antibodies Vaccinate healthy animals only [34]
Strangles	Primary vaccination course: Administer one dose (2 ml) by intramuscular injection, followed by a second dose (2 ml) 4 weeks later. Revaccination: In horses at high risk of S. equi infections it is recommended to repeat the primary vaccination regimen after two months [35]	Vaccinate healthy animals only Effect of vaccination on further stages of the infection, rupture of developed lymph node abscesses, prevalence of subsequent carrier status, bastard strangles (metastatic abscessation), purpura haemorrhagica and myositis and recovery, is not known Efficacy has been demonstrated for the individual horse to reduce clinical signs of disease in the acute stage of the infection. Vaccinated horses can be infected and shed S. equi [35]
Equine herpes	Primary course: A single dose should be administered from five months of age followed by a second injection after an interval of 4–6 weeks In the event of increased infection risk, for example when a foal has consumed insufficient colostrum or there is a risk of early exposure to field infections with EHV‐1 or EHV‐4, earlier vaccination may be given In these circumstances the foal should receive a single dose from three months of age followed by the above mentioned full primary vaccination course Revaccination: Following completion of the primary course, a single dose should be administered every six months Use in pregnant mares: To reduce abortion due to EHV‐1 infection, pregnant mares should be vaccinated during the 5th, 7th and 9th month of pregnancy with a single 1.5 ml dose on each occasion [36]	Vaccinate healthy animals only [36]
Equine viral arteritis (Notifiable disease)	Primary course: administer dose (1 ml) by intramuscular injection followed by a second 1 ml dose 3–6 weeks Horses can be vaccinated form the age of nine months onwards Revaccination: Recommended every six months [37]	Vaccinate healthy animals only Vaccination does not prevent infection Vaccination does not have an effect on the shedding of EAV by previously infected carrier stallions The effect of the vaccine on the fertility of breeding stallions has not been investigated. Under some national legislation EVA is a notifiable disease (UK). Please refer to the national product literature for recommendations on vaccination to comply with this legislation Equine viral arteritis (EVA) is a notifiable disease in the United Kingdom. Vaccinated horses will become seropositive and therefore it is recommended that they are blood tested prior to primary vaccination to demonstrate that they were previously seronegative. Details of blood testing and vaccination schedule should be recorded in the horse passport Do not use in pregnant mares [37]

^a In January 2024, vaccination rules for equine influenza changed for many equestrian disciplines in accordance with advice from the British Equestrian Federation (BEF). Vaccination rules differ between different sporting bodies, but a summary is as follows. The interval between the 1^st and second vaccination has changed from 21‐92 days to 21 to 60 days. The interval between the second and third vaccination has changed from 150‐215 days to 120‐180 days. Booster vaccinations are to be given within 6 or 12 months depending on the requirements of the relevant governing body. Readers are encouraged to check the most up to date guidelines.

Type of parasite	Species	Clinical particulars	Diagnosis method
Small red worms	Cyathostomes	The normal lifecycle takes place over a few weeks from ingestion of larvae to adult egg laying worms (Figure 5.3). However, these worms have the ability to hibernate within the gut wall in small cysts. The emergence of large numbers of larvae all at the same time (usually during the late winter) can cause huge damage to the gut lining. This can cause inflammation, diarrhoea, colic and death in up to 50% of affected horses [39]. This condition is known as cyathostominosis	Faecal worm egg count (adults only). Blood test (encysted larvae)
Large red worms	Strongyles – Strongylus spp.	Larval stage of Stongylus vulgaris can migrate through blood vessels to develop within the major artery supplying blood to the intestinal tract (Figure 5.4). This migration not only damages the blood vessel walls, but can also lead to blood clots and a weakening of the blood vessels. Some species damage the liver and other internal organs with disruption to the blood supply that can cause colic and, in rare cases, death [39]	Faecal worm egg count
Adult roundworms	Parascaris equorum	Adult large roundworms can reach up to 50 cm in length. Large roundworms typically only affect foals and young horses, as older horses develop an immunity to them [39]. Adult ascarids and migrating larvae can cause poor growth, digestive and respiratory problems and occasional fatalities. The eggs of large roundworms can survive in the soil and in stables for many years. Young horses become infected by ingesting these eggs from the pasture and their surroundings. Clinical signs can include: coughing, a pot‐bellied appearance and weight loss	Faecal worm egg count
Pinworms	Oxyuris equi	Pinworms inhabit the colon and are not thought to be harmful. However, pinworms can cause pruritus incited by the egg‐laying behaviour of the female worms and by the sticky egg masses in the perianal region when drying, which can result in scratching and damage to the tail	Pinworm eggs are not normally found in faecal samples, diagnosis is normally made by microscopic examination of sticky tape preparations taken from around the anus [39]
Tapeworms	Anoplocephala perfoliata	The tapeworm requires a host in the form of the forage mite. Eggs develop within the mite which is then ingested by the horse. The eggs are then released during digestion into the intestines where they attach to the lining of the intestines and continue to develop into adult tapeworms. These tend to congregate around the narrow junction of the small intestine and the caecum (the ileocaecal junction). The presence of large numbers of worms here can cause an impaction to occur and the horse to display colic symptoms. Severe tapeworm infestations can cause digestive disturbances, loss of condition, colic and death. An antibody‐based blood test (ELISA) or a saliva‐based test, can be used to determine the level of exposure in individual horses	Blood or saliva test
Lungworm	Dictyocaulus arnfieldi	Donkeys are thought to be the natural host of this parasite, but horses can also be infected with lungworms. This infection is likely to occur when horses share the same grazing as donkeys. Donkeys can tolerate a large infestation of lungworms without any obvious signs, whereas infected horses show obvious respiratory signs, such as persistent coughing, weight loss and poor performance. Horses and donkeys can live together safely as long as an appropriate worming programme is in place	Faecal worm egg count
Bots	Gastrophilus intestinalis	Bot flies are a common irritant to grazing horses during the summer months. The female flies lay their small, sticky yellow eggs on the coat of the horse, typically on the forelegs, shoulder or abdomen. As the horse licks itself, or is groomed by another horse, the eggs hatch and the larvae are transferred into the mouth of the horse, where they burrow into the tissues of the tongue and mouth before being swallowed. Once in the stomach, the larvae attach themselves to the gut lining to continue their development through the winter. The ‘bots’ eventually detach to continue unharmed through the digestive system to be passed out in the faeces. After pupating in the ground, they emerge as a new generation of flies. Advising clients to remove the eggs from the horse daily with a bot knife can help to disrupt the life cycle [39]	Bot eggs are visible on the coat of the horse. Bot fly larvae are occasionally seen in the stomach of the horse during unrelated gastroscope examinations

Strategic Dosing

This is the use of drugs at specific times of year to disrupt the seasonal cycle of transmission [40]. This helps to disrupt the seasonal cycle and transmission of parasites by reducing parasite egg output by horses. This also prevents the build‐up of larvae on the pasture. However, problems can arise as a result of abnormal weather patterns. For example, wet, warm summers can lead to early or late peak pasture larval burdens [40].

Targeted Strategic Dosing

Faecal worm egg counts (FWECs) are measured prior to dosing (see Chapter 8 for further information). This is a test which counts the number of worm eggs (Figure 5.5) in a sample of faeces and gives a good idea of the horse’s roundworm burden, if any. Only horses with FWECs over 200 eggs per gram (EPG) are wormed. This is the strategy best suited to minimise the problem of resistance to wormers. FWECs should be performed every 8–10 weeks. Diagnostic limitations mean that negative FWECs do not guarantee a horse is parasite‐free as, for example, a horse may be harbouring immature parasites which have not yet started to produce eggs. Also, small redworms developing in the gut wall cannot be detected by this method. For this reason, it is recommended that a blood test is performed to determine the presence of small strongyles. If this is not possible, an anthelmintic capable of treating encysted cyathostomes should be administered to the horse in late autumn/early wintertime. Tapeworms are not detected by routine FWECs, so a enzyme‐linked immunoassay (ELISA) (blood) test or tapeworm saliva test should be carried out in the spring and autumn [39].

If strongyle or ascarid related anthelmintic resistance is suspected, Faecal worm egg count reduction (FWECR) tests can be performed. FWECRT tests are performed by collecting a faecal sample prior to worming and performing an initial FWEC test. The anthelmintic in question is then administered and another faecal sample is collected 14 days following treatment. The following equation is then applied to calculate the percentage reduction in the faecal egg count for the horse individually [41].

This test can also be used to assess the presence of anthelmintic resistance in a group of horses. The results of the FECRT should inform the anthelmintic dosing strategy moving forwards.

Anthelmintics

There are different classes of anthelmintics which are available to treat and kill endoparasites. They are grouped into different classes for their effectiveness on targeted species. The four groups are:

• Pyrantels
  
• Macrocyclic lactones (Ivermectin/moxidectin)

  

  
  
• Benzimidazoles (fenbendazole)
  
• Praziquantel

The different active ingredients in the classes can be used alone or in combination to treat several different endoparasites (Table 5.5).

Prescription of Anthelmintics

All anthelmintics are licensed by the VMD and are given a pharmaceutical class. They are usually Prescription Only Medicines (POM) that can only be prescribed by a Vet, Pharmacist or Suitably Qualified Person (SQP) or Animal health Advisor (POM‐VPS), who holds the qualification to prescribe equine anthelmintics. A clinical assessment of the animal is not required when prescribing this classification of veterinary medicine, and the animal does not have to be seen by the prescriber. However sufficient information about the animal and the way it is kept must be known to the prescriber in order to prescribe and supply appropriately [42]. See Chapter 9 for more information.

Owner Guidance

National Equine Health Survey (NEHS) 2015 results showed that many horse owners were not worming correctly. About one third of people who thought they had treated for encysted cyathostomins had used an unsuitable product, while around 7% used a product that resistance had been reported on, indicating some horse owners still did not know how to effectively control worms [39]. This is an area where RVNs and SQPs can play an important role in communicating best practice parasite control guidelines. Once a worming protocol has been selected, it is important to advise clients on how to estimate the dose of the wormer accurately. Under‐dosing horses with wormers can contribute significantly to anthelmintic resistance. Conversely, over‐dosing horses with wormers can cause some unpleasant side effects. The simplest way to encourage clients to assess the bodyweight of their horse correctly is via the use of a weigh tape. These are cheap to purchase and easy to use. Ideally, an electronic weighbridge could be used to gain an accurate weight for each horse, but this is not always possible due to transport limitations. Some practices/feed companies will take the weighbridge out to yards and offer weighbridge clinics, which can also be very useful for clients. It is important that RVNs and SQPs make clients aware of all the options available, so that they can make an informed choice.

BEVA have produced a toolkit called protectMEtoo to assist vets, RVNs and practices to develop anthelmintic policies for the better, more responsible use of dewormers. More information can be found in the Further Reading section.

Ectoparasites

Ectoparasites are parasites found on the outside of the body within the skin and hair. They may be host specific and some can potentially affect other species. With any ectoparasitic infection it is important to observe good hygiene between patients so as not to initiate the spread of any parasites. Wearing gloves, washing and disinfecting grooming tools, feed and water buckets, and avoiding the sharing of stable tools will all help to limit the spread of disease. Horses that have an ectoparasitic infestation should be tended to last to avoid spreading the parasite to other patients in the practice.

Mites

Chorioptes is a mite which causes chorioptic mange in horses (Figure 5.7). The mite has eight legs and resides on the skin surface. They are most commonly found on heavily feathered types such as cobs. A common presenting sign is that the horse will stamp their feet and rub their legs on objects in the stable due to local irritation. Chorioptes may be identified by a skin scrape. They are most prevalent in the winter months. Transmission is by direct and indirect contact. Treatments can be topical as for lice, or a more effective treatment is with an off‐license course of the cattle wormer doramectin. Clipping of the feathers may aid in the prevention of infestation [43].

Active ingredient	Small red worm adults	Small redworm larval stage	Strongyles	Roundworms (Ascarids)	Pin worm	Tapeworm	Bots	Lungworm	Comments
Fenbendazole	✓	✓	✓	✓	✓	X	✓	✓	Five‐day course can be used against inhibited mucosal stages of small redworms. Use in conjunction with FWEC and blood test for encysted small redworm larvae. There is widespread resistance to this wormer group against small redworms
Pyrantel	✓	X	✓	✓	✓	✓ (Double dose only)	X	X	Double dose in spring and autumn (March/April and September/October). Use in conjunction with FWEC, tapeworm ELISA and/or saliva tests
Ivermectin	✓	X	✓	✓	✓	X	✓	✓	Dose according to results of FWEC
Moxidectin	✓	✓	✓	✓	✓	X	✓	✓	Use in conjunction with FWEC or blood test for encysted small redworm larvae. If this is not possible, one single dose required in late autumn/early winter to treat encysted small redworms
Praziquantel	X	X	X	X	X	✓	X	X	Dose in spring and autumn. Dose based on the results of ELISA blood sample or saliva test
Ivermectin & praziquantel (combination wormer)	X	✓	✓	✓	✓	✓	✓	✓	Single dose in spring and autumn (March/April and September/October) for roundworms and tapeworms. Use in conjunction with FWEC and tapeworm ELISA/saliva test
Moxidectin & praziquantel (combination wormer)	✓	✓	✓	✓	✓	✓	✓	✓	Use in conjunction with FWEC, blood test for encysted small redworm larvae, and tapeworm ELISA tests. If this is not possible, one single dose required in late autumn/early winter to treat encysted small redworms. This is the newest equine wormer on the market. It must be used carefully and strategically to help to lower the risk of anthelmintic resistance developing

Sarcoptes scabiei are burrowing mites that affect domestic animals and humans. They are responsible for causing sarcoptic mange which is rare in the horse. Clinical signs include pruritis and severe self‐trauma often accompanied by excoriation (self‐trauma) and skin damage. Deep skin scrapings are required in order to identify this mite. They are smaller than other mites, measuring up to 0.4 mm in length. They are rounded in shape and are covered in distinctive ridges and scales on their dorsum [43].

Culicoides

Culicoides are small midges which cause intense irritation to most mammals and humans. Some horse and ponies develop a hypersensitivity to the saliva of the culicodes midge. Clinical signs include rubbing the mane and head of the tail until it is inflamed, bleeding, and hair loss occurs. This condition is more commonly referred to as ‘sweet itch’. The midge is also a vector for spreading disease [43]. There are many topical remedies available however, prevention is better than cure. Management strategies include:

• Avoiding turnout near open water.
  
• Housing horses when midges are at their most active for example at dawn and dusk.
  
• Using fly rugs which cover the mane and tail.
  
• There is a ringworm vaccine which has been known to provide some relief when used off license for the prevention of sweet itch. Two doses are given two weeks apart in February before the midges start to populate.

Appearance

It is important to be aware of what is normal in terms of the appearance of the horse so that any abnormalities can be identified and addressed promptly.

• Eyes: The eyes should be open, clear and produce no discharge. The eyelids should close naturally.
  
• Ears: The pinna of the ear should be rigid and highly mobile. The horse will constantly move its ears to listen to the source of different sounds. Disorder affecting the ear are uncommon int the horse.
  
• Mouth: Incorporates the lips, teeth, tongue and oral cavity. The lips and incisors are responsible for taking food into the mouth. Lip injuries can occur from poor bitting and trauma.

Nutrients are food components that help to support life [44]. An essential nutrient is one that is required and unable to be synthesised in the body and therefore must be provided as a dietary source. Nutrients are split into energy‐producing nutrients and non‐energy producing nutrients [44]:

• Energy producing nutrients: Carbohydrate, protein and fat
  
• Non‐energy producing nutrients: Vitamins, minerals and water

Macronutrients

Carbohydrates

Carbohydrates are composed of the elements carbon, hydrogen and oxygen and serve to provides a major source of fibre and energy within the horse’s diet. [44]. Carbohydrates can be classified as monosaccharides, disaccharides or polysaccharides:

• Monosaccharides: Are commonly referred to as simple sugars, are the simplest form of carbohydrate, and include glucose, fructose and galactose. They are found as components of large carbohydrate molecules in legumes and cereals grains. They are broken down in the stomach and small intestine. Fructans found in grasses are fermented in the hindgut. Excessive feeding of non‐structural carbohydrates can lead to over production of lactic acid, a fall in pH. and destruction of microbes leading to the release of toxins implicated in laminitis, colic and endotoxaemia [44]. Glucose peaks at 1–3 hours after feeding which is associated with a rise in insulin. This may slow the release of free fatty acids (FFAs) into the circulation, so glycogen stores are used. If the equid is exercised at this stage, there may be a drop in blood glucose during the first stages of exercise, which may not be desirable because the brain can only use glucose as a fuel [45].
  
• Disaccharides are composed of two monosaccharide molecules linked together and include sucrose (glucose and fructose), commonly found in grass and legumes, maltose (glucose and glucose), which is produced as an intermediate in hydrolytic digestion of starch, and lactose (glucose and galactose), which is important for young foals [44].
  
• Polysaccharides are more commonly referred to as complex carbohydrates and consist of vast numbers of linked monosaccharide molecules [44]. Examples include starch, glycogen and fibre. Dietary fibre or roughage includes the polysaccharide cellulose (present in the cell walls of plant cells), pectin and lignin. Polysaccharides are fermented in the hindgut by microbes and volatile fatty acids (VFAs) are produced and absorbed into the bloodstream. The are then used as a source of energy immediately or stored as fat [44].

Protein

Protein is a molecule made up of chains of individual amino acids which are linked together by peptide bonds to make polypeptides, and when protein is consumed in the diet, these bonds are broken down so the amino acids can be absorbed for use in protein synthesis and metabolism. The protein or essential amino acids needed by the horse must be provided in the diet as they cannot be manufactured by the body. These include arginine, histidine, leucine, phenylalanine, methionine, isoleucine, lysine, threonine, tryptophan and valine. Important functions of protein in the body include structural enzymatic and hormonal roles, transport of nutrients across membranes and in the blood, and as a component of the immune system [46]. The mature horse requires only moderate amounts of protein approximately 8–10% of the daily ration. Higher amounts of protein, up to 16% of daily ration, are needed for the following horses: geriatric, pregnant, lactating, performance horses and youngstock. Protein is not an efficient energy source, and any excess will be converted into carbohydrates or broken down into urea. Protein is absorbed in the small intestine after being broken down into individual amino acids or small peptides [44].

Fats/Lipids

A typical forage‐based equine ration should meet a horse’s essential requirement for fatty acids, but additional fats may be required to aid in weight gain, managing inflammatory conditions like arthritis, or preventing and managing gastric ulcers. Performance horses require a large amount of digestible energy to support high‐intensity performance, so feeding additional fat can increase the calorific density without increasing volume. Dietary sources of fat are available in commercial concentrate feeds, or feed grade oils such as vegetable, soya or corn. The amount to feed is based on the needs of the individual, or the required effects [45]. Any supplemental oil should be introduced slowly. 10% of the daily diet is suggested as an optimum level when incorporated in a complete and balance feed [44]. Adding oil to an existing feed has the potential to create multiple imbalances and therefore, levels of 5‐8% in the total diet are more commonly recommended for high performance horses [44]. A good starting amount is around 0.1ml per kg bodyweight to gradually be increased to around 1ml/kg of bodyweight divided into daily doses.

Micronutrients

Vitamins

Additional vitamins and minerals should not be required if the diet being provided is well balanced. Although health status, individual needs, environmental conditions and workload may necessitate the need for supplementation, see Table 5.7 for guidance. The most common supplements are vitamins and minerals, salt, electrolytes and herbs. All of these are manufactured by feed companies and sold commercially in liquid, powder or pellet form.

All vitamins share certain characteristics, such as:

• They are essential for normal physiological function.
  
• An absence can cause a deficiency syndrome.
  
• They are synthesised in the body to level that supports normal function.

Vitamins are divided into fat soluble A, D, E and K and water‐soluble groups B and C. Fat soluble vitamins require bile for their absorption and are stored in body fat which makes them more prone to surplus storage rather than deficiency. Water soluble vitamins are absorbed via active transport and are not stored therefore a deficiency in these vitamins is more likely [44]. Thiamine, riboflavin, folic acid are important B vitamins that are required in the horse’s diet. Vitamin B12 is not believed to be required other than the amount provided by microbial synthesis and no deficiency has yet been observed in horses [45]. The vitamin C needs of healthy horses are met by tissue synthesis however, horses that have been subjected to trauma, disease or major surgery may require supplementation [45].

Minerals

Minerals are essential in the body for structural components, body fluids, and as catalysts and cofactors for enzymes and hormones. They are classified into macro minerals and micro minerals.

Macro minerals for horses include calcium, phosphorus, sodium, chloride, potassium, magnesium, and sulphur. These minerals are crucial for various bodily functions, including bone formation, nerve function, and muscle contraction. Although these minerals are generally available in a balanced diet, their absorption and utilisation are influenced by several factors, such as the mineral content in the diet, the individual horse’s needs, physiological demands, and environmental conditions. Both deficiency and excess of any mineral can lead to health issues, making it essential to use supplements with caution. Over‐supplementation can be as harmful as deficiencies, potentially leading to toxicity and other health problems. For more detailed information on the appropriate levels and sources for these minerals, refer to Table 5.8.

Microminerals, or trace elements essential for horses, include zinc, iron, copper, and selenium. These trace elements are vital for various metabolic processes, immune function, and overall health. A deficiency in these trace elements can have significant physiological effects, such as impaired growth, weakened immune response, and other metabolic disturbances. Therefore, monitoring and diagnosing any deficiencies accurately before initiating supplementation is important to avoid adverse effects associated with improper dosing. Proper diagnosis and targeted supplementation are key to maintaining optimal health in horses [44].

Water

Horses require a constant supply of clean, fresh water as it is a vital nutrient and makes up 60–70% of the body. As a general rule, horses require a minimum of 5 litres per 100kg bodyweight. Water requirements increase with environmental temperature, for example, a rise from 15°C to 20°C will increase water loss by 20% and will therefore increase an adult horse’s water requirement by approximately 5 litres [44]. The effects will be greater in the foal, especially in the neonate as they have a greater surface to body mass ratio and an inability to efficiently concentrate urine.

The functions of water in the body are as follows [44]:

• Electrolyte balance
  
• Temperature regulation
  
• Removal of waste products
  
• Transport medium for nutrients
  
• Major component of blood and lymph
  
• Required for chemical reactions involving hydrolysis
  
• Regulates oncotic pressure

Water can be provided through an automatic water dispenser, water troughs and containers or via a natural free running source such as a stream. Monitoring the water intake of patients is an essential part of nursing care. Within a hospital or practice setting, automatic water drinkers are not suitable, as it is not possible to monitor water intake. Suitable containers should be used to allow for the amount of water consumed to be assessed. Such containers should be regularly checked refilled and cleaned. Extra water should always be provided during the warmer months. In the winter, ice should be thawed or removed from water buckets regularly.

The factors affecting water requirements include:

• Lactation
  
• Exercise
  
• Stress
  
• Illness
  
• Diarrhoea
  
• Reflux
  
• Environmental temperature
  
• Body temperature
  
• Type and amount of food ingested
  
• Water losses through excretion or evaporation

Water losses can be replaced through water derived from the metabolism of nutrients, by consumption of water or within the food ingested. High performance horses will lose large amounts of water and electrolytes in sweat. In these cases, access to water, salt blocks (or the use of added electrolytes) should be facilitated to assist in replenishing these losses [44].

The Effects of Balanced Nutrition on Bodily Functions

To maintain a consistent body weight and composition, a horse’s maintenance nutritional requirement should be provided. An individual horse’s nutritional requirements will depend on several factors including:

• Bodyweight
  
• Breed
  
• Age
  
• Growth
  
• Reproductive needs
  
• Exercise intensity
  
• Environmental factors
  
• Health status

Each horse has a differing metabolic efficiency, appetite, temperament, and health status, all of which influences their requirements alongside balancing intake with usage. Forage alone may be all an individual needs to achieve maintenance requirements, but if forage alone is not enough, concentrates and legumes can be added to satisfy their needs [45].

To ensure the appropriate and adequate supply of energy is provided to maintain health and vitality, the energy potential of feed needs to be determined and this is done using four pieces of information [44]:

• Gross energy (GE) refers to the total heat produced from the digestion of a food source.
  
• Digestible energy (DE) is the portion of the food’s energy content that can be digested and absorbed by the horse.
  
• Metabolised energy (ME) is the energy remaining after subtracting the energy lost in urine and gases from the DE.
  
• Net energy (NE) is the GE minus the energy lost in faeces, urine, gases, and heat

Thermoregulatory mechanisms in horses are important to ensure they maintain a state or normothermia and do not develop either hypothermia or hyperthermia. Horses utilise convection, radiation, evaporation, and respiratory losses to remove heat from the body. To increase their internal temperature, they utilise their gastrointestinal tract. Food sources are digested in different parts of the gastrointestinal tract, but the main area of heat production occurs in the hindgut due to the fermentation that arises in the colon and caecum. Good quality forage will provide the maintenance energy requirement, but cereals maybe required to increase energy demands as they are more rapidly absorbed. Newborn foals have a poor ability to thermoregulate and maintain their body temperature through muscle activity, food intake and shivering. Therefore, a continual supply of milk during the early stages of life is imperative to maintain normothermia. As they develop into the weanling, yearling and youngster phase, their ability to thermoregulate is much improved but again, they need an adequate level of food intake to achieve this. Adult horses maintain their body temperature well if they are in good health and have a supply of forage and concentrates to supplement their energy requirements and allow thermoregulation to occur. In the geriatric or sick horse, thermoregulation can be assisted with the use of rugs, extra bedding, and heat lamps, which can all help to increase the body temperature of a hypothermic patient. Fans, cooling baths or clipping may be required to lower body temperature. Clipping may be required for patients with PPID or ECD, as they may struggle to thermoregulate due to the hirsutism (long, curly coat).

Monitoring of body weight and condition is important to ensure over feeding does not occur, as this will result in storage of excess as fat that can lead to obesity. This could lead to health issues such as insulin resistance, metabolic issues, laminitis, reproductive complications, liver conditions, lipomas, and gastrointestinal problems. Body condition scoring is a useful way of monitoring the condition of an animal and involves an assessment of fat stores on the horse’s body. During a body condition score, different areas of the horse are felt to assess fat coverage and give the horse an overall body condition score. Fat feels soft and spongy, but dangerous amounts of fat in areas such as the crest of the neck feel hard and wobbly. In contrast, muscle feels firm but not hard. Regular body condition scoring allows the weight of the horse to be monitored over time and facilitates nutritional modification to ensure optimum health for each individual, which includes underweight horses as well as overweight ones. Figure 5.8 is a guide for body condition scoring in the horse. Body condition scoring in donkeys is different, please see Chapter 16 for more information.

Feeding according to the individual and its workload will ensure homeostasis is maintained. This is achieved by feeding according to energy requirement but also taking into consideration age, health, workload, the body condition required, and environmental conditions. If these factors are not considered, the result will be a under or overweight horse and both these conditions can lead to health implications. The implications associated with obesity have been mentioned previously and some of those conditions are also prevalent in underweight equids such as metabolic issues, gastrointestinal complaints, immunosuppresion and gastric ulcers.

Metabolic processes within the body provides the energy required to sustain anabolic and catabolic reactions. Anabolic reactions use energy to build structural components of the body such as muscle tissue. Whereas catabolic reactions break down large particles into smaller ones and produce energy. Most anabolic reactions occur shortly after feeding, while catabolic reactions tend to occur several hours if not a day after feeding, or after exercise when energy is required. If the metabolism is supported with a balanced diet, these reactions can occur with ease. If the body is lacking nourishment or exertion levels are high, the body cannot maintain the energy requirements, and this therefore puts stress upon the body system which can lead to health issues such as depression, dehydration, fatigue, poor performance [47].

Appetite is driven by several factors in horses which include routine, quality of feed, health, exercise, physical status, mental status, and hormonal status, all these factors can have a positive and negative effect on individuals. Horses thrive on routine and when this is disrupted, it can have a knock‐on effect on wellbeing. This can include a reduction in appetite due to stress and anxiety. If left untreated, this could lead to health issues such as gastric ulcers. It is also important to provide good quality feed, and this has less to do with the cost of the feed, and more to do with how the feed is stored. The feed provided must be in date and stored in a dry cool container to ensure there is no damp, dust or mould within the feed. Such contaminants can make the feed unattractive and lead to inappetence and or health issues.

Hormonal factors can also affect appetite especially in breeding animals, stallions often become inappetent during the breeding season due to being so focused on procreating. This can also occur in mares when in season due to hormonal changes. Management in these situations is important to ensure good health is maintained. Studies have been carried out to assist feed companies to create the most attractive feed products for horses, but especially those in poor health as inappetence is commonly one of the first signs to occur. The studies have shown that blackcurrant, banana and mint are the most favoured flavours to be incorporated in commercial concentrates to increase their palatability.

Domestication has changed the nutritional requirements of horses in comparison to wild horses, mainly due to increased energy demands. Wild horses forage for high fibre diets, mainly eating grasses and other herbage which suit their gastrointestinal tracts. Domesticated equids have had to adapt to a change in their diet which includes the introduction of cereal grains alongside their daily forage. Sometimes, this causes complications within the gastrointestinal tract resulting in several types of colic such as colitis leading to diarrhoea, spasmodic colic, or laminitis. It is therefore imperative that any changes to the diet are carried out gradually and with caution. Wild horses are constantly on the move which helps promote gut motility. Domesticated horses are often stabled for long periods of time, and this can reduce gastrointestinal motility and make them more prone to developing impaction colic. This must be managed appropriately, and interventions should be tailored to the individual. This may include considerations such as the horse living out 24 hours a day.