Introduction
Stereotypical behaviours are defined as apparently functionless, repetitive patterns of behaviour (Cooper and McGreevy 2007). They are thought to have developed through frustrated attempts to satisfy a desired need, in an environment that does not supply the horse with the ability to satisfy that desire or need (Henderson, 2007). The action then becomes chronic, repetitive and functionless as that need cannot be satisfied. Stereotypical behaviours have never been evidenced in feral environments and are referred to as ‘the disease of domestication’ (Marsden, 2002). Stereotypical behaviours are commonly exhibited amongst stabled horses, and have been found to affect between 10 and 40% of these (Nicol, 1999). Stereotypical behaviours are often considered to be extremely undesired due the impact upon the horses’ health and the subsequent loss of economic value of the horse (McBride and Long, 2011).
There are several types of stereotypical behaviours and are caterogised as either locomotor or oral stereotypies. Locomotor stereotypies include weaving and box walking; weaving is defined as lateral swaying of the head and neck and weight shifting between the forelimbs (Henderson, 2007), whilst normally the horse remains stationary, however it can also lead to the picking up of the front feet (Cooper and McGreevy, 2007). Weaving can result in uneven muscle development, weight loss and fatigue (Sarrafchi, 2012). The prevalence of weaving is thought to be between 3-5% of the equine population (Luescher, 1998). Box walking consists of a pacing motion around the stable, either in a circular or irregular pattern, and is associated with a loss of condition and a reduction in ridden performance (Sarrafchi, 2012). Box walking has been reported to affect over 2% of stabled horses. Oral stereotypies are most commonly divided into crib-biting and wind-sucking; cribbing refers the behaviour when a horse uses its incisors to grasp a fixed surface whilst contracting the neck muscles and pull backwards (Albright et al, 2009). As a result of crib-biting tooth wear is an inevitable consequence, unless specific modified areas are provided (McGreevy, 1995). Whilst tooth wear is unlikely to become a source of pain, it can however, result in a loss of condition and body weight due to potential difficulties in chewing (Sarrafchi, 2012). In addition, weight loss may also occur through increased energy expenditure, combined with less time spent resting and eating (McGreevy, 1995). Cribbing has been reported to affect 6.3 % of the general equine population (McGreevy et al, 1995). Finally, windsucking is a very similar behaviour, except the horse does not seize an object, and instead air is forced into the esophagus by the neck muscles (Albright et al, 2009) and it is often thought that windsucking behaviour predisposes crib-biting (Cooper and McGreevy, 2007).
In the present case, the horse presents with crib-biting, box walking and weaving behaviours. The effect upon the horse’s health and welfare is detrimental, as due to a recent injury the horse has been placed upon box rest. However, the horse has presented with a loss of condition, reduction in weight and severe stress. In order to allow the healing of the injury, along side managing the stereotypical behaviours a review of the causes and potential solutions to these behaviours is vital.
Overview of General Wellbeing
‘The Chisolm’ (stable name Collin) is a 14 year old, 16’3hh, bay Thoroughbred gelding. He has many behavioural issues including box walking, weaving and crib biting and has been in his present home for the past 3 years. At the age of 2 years old he came to England from Ireland to begin his racing career. He was raced until the age of 10 years old before being sold to his current owner. His racing career was not one of success, out of the four recorded races, he only completed one. He was competed at National Hunt flat racing, Team Chase and Hurdles. His most successful race was at the age of 5, when he came 12th out of a possible 16 during a National Hunt race. The previous owner, also the horse’s breeder stated that the stereotypical behaviours began as he was brought in for initial training, and suggested that the use of a anti-weave bar and a cribbing collar were successful methods of reducing the behaviours, however claimed that they did not affect his ridden ability.
Before being purchased he was stabled in a single stall with visual but no physical access to conspecifics, for 24 hours a day, and had an anti-weave bar on his stable door. He also presented with gastric ulceration of the squamous mucosa and excessive wear on his incisors as a consequence of the stereotypical behaviours. The previous owner and breeder claimed that the stomach ulcers had developed in recent years, however it is possible they may have developed as early as weaning due to the stress implications. Upon purchase his teeth were rasped, however the gastric ulcers were left due to the concerns of financial implications. The client claimed that the ulcers do not impact the horse negatively and do not affect ridden behaviour. The horse was purchased to compete at local Cross Country Events and Fun Rides. The owner did not feel that his behaviours would pose as a problem, as she anticipated he would be on 24-hour turnout, and the horse does not present any stereotypical behaviours during turnout.
However, due to a recent injury, he is on box rest and will remain so for several months. As a consequence of this, his stereotypical behaviours are prominent and he has suffered from severe weight loss. The client observed that in a 5 minute period, the horse exhibited crib-biting 30 times, box walking 10 times and weaved on 8 separate occasions. The client is concerned that his stereotypies could seriously affect his foot from healing and his lack of condition is an additional concern. WHAT IS WRONG WITH HIS FOOT? Following the period of box rest, he will remain on limited daily turnout in a small paddock, before being turned out completely.
His stable is currently fitted with anti-weave bars (Photograph 1), however he is still expressing these behaviours inside his stable. He has visual access to conspecifics in a nearby field for the majority of the day, however due to the warming weather conditions no other horses are being stabled at this time. Typically he is fed two large concentrate meals per day (morning and evening); the client stated that his cribbing behaviours often increase around meal times. The horse is provided with fresh water through an automatic drinker, and is given two haylage nets following the morning feed. His bed consists of shavings and is skipped out daily, whilst the bed is changed weekly.
Photograph 1: The client’s horse in his current stable fitted with anti-weave bars
Evaluation of Stereotypical Behaviours and Practical Recommendations
Currently, an anti-weave bar is fitted to the stable to prevent the horse from performing this behaviour. However, physical prevention of stereotypical behaviours has proven to have detrimental effects to the horses’ welfare (Sarrafchi, 2012). Prevention through physical means such as cribbing collars and anti-weave bars have shown to significantly increase physiological responses which are consistent with the stress response; increased heart rate and adreno-corticol activity levels (McBride & Cuddeford 2001). Furthermore they have be found to be ineffective in reducing these behaviours; instead of weaving over the stable door, the horse moves inside the stable to perform the behaviours. Furthermore, the use of a cribbing collar can result in the ‘rebound effect’; McGreevy and Nicol (1998) measured the effect of a cribbing collar in reducing the rate of crib-biting. Although the cribbing collar appeared effective whilst in use, after it’s removal there was a highly significant increase in the rate of crib-biting. This reaction was suggested to be a result of an increase in the internal motivation to perform the behaviour during the prevention, and a consequential increase in the behaviour once it was removed. This prevention was defined as a compromise to welfare and is suggested to be an unsuccessful method of prevention (McGreevy and Nicol, 1998). In this case, the previous use of a cribbing collar may have negatively affected the rate of crib-biting, as well as impacting the welfare of the horse. It is recommended that the anti-weave bars are removed from the stable as they have shown to be ineffective.
The method of weaning in this case was box, however it would appear that he was turned out on paddock post weaning. When the horse came back in for initial training as a one year old, these behaviours were displayed almost immediately. Research has found a link between the method of weaning and the onset of stereotypies; Waters et al (2002) found horses which were box or barn weaned were significantly more likely to develop behavioural problems than for those weaned in any other way. Furthermore, for those box weaned, were twice more likely to develop such behaviours than those barn weaned. In addition, the study found young horses fed concentrates after weaning were 4 times more likely to crib bite than those who did not. The feeding of concentrates post weaning is common practice, often due the to foal accessing their dam’s feed or to encourage growth (Waters et al, 2002).
The feeding of concentrates is thought to be a significant factor in the development of stereotypies, not only post-weaning but also in later life. Horses are naturally free ranging and spend the majority of the day grazing. Studies reference more than 50% of time each day is spent eating (Boyd, Carbonaro and Houpt, 1988) in feral counterparts. However, modern management of equines generally results in stabling and the restriction of forage activity. Stable rations often involve highly concentrated meals with limited access to high fibre forage (Cooper et al, 2005). In particular, horses in race training are typically fed high-concentrate, low-roughage diets (Hammond, Mason and Watkins, 2010). This was likely to have been the case during the horse’s time spent in training.
Currently, the client’s horse is fed two meal of concentrates (morning and evening) everyday, whilst two large haynets are filled each morning post feed. The client reported an increase of crib-biting around mealtimes. This is supported by extensive research, which suggests that stereotypies are at their peak prior and post to the feeding of concentrates; prior to feeding, animals often perform species specific activities, such as pacing behaviours in mink (Mason, 1991). The behaviours may increase either due to a lack of satiety following the feed (Hughes and Duncan, 1988) or become exaggerated due to the apparent feed reward (Cooper et al, 2005). In relation to the horse, behaviours including weaving, pawing and box walking may occur as an initial anticipatory response to meal times, however they may be encouraged due to the appearance of feed and therefore are positively reinforced. Furthermore, following a meal, if it fails to meet the necessary consummatory stimuli (Hughes and Duncan, 1988) feeding behaviour can continue. However, if the availability of such behaviours is not met, re-direction behaviour can occur, particularly in the form of oral stereotypies (crib-biting and wood chewing). However, this may be solved through providing ad libitum forage; a study by Marsden (1993) found that providing forage in the form of soaked hay significantly reduces crib-biting and wood-chewing after the feeding of concentrates.
McGreevy et al (1995b) found a significant association between lower amounts of forage and increased stereotypical behaviours, such as wood-chewing and weaving. Horses fed less than 6.8kg of forage per day were more likely to exhibit these unwanted behaviours. This is supported by later research; Willard et al (1997) found the feeding of a low forage diet in the stabled horse increased the prevalence of wood chewing than those fed hay. The role of forage in the reduction of stereotypical behaviours appears to be of importance; feeding high quantities, particularly following a concentrate meal is suggested to assist in the management of these behaviours.
Due to the association between meal times and the onset of stereotypical behaviours, recent research has focused upon methods to improve management methods. Cooper at al (2005) observed the affect upon increased meal times and the onset of stereotypical behaviours. The results found by increasing meal frequency from 2 to 6 times per day decreased the onset of crib-biting behaviours. However, an increase in both weaving and nodding was found as a result of meal frequency. It was suggested that both of these behaviours were anticipatory responses to feeding and occurred as a result of previously learnt feeding cues, such as noise from the feed room. Therefore, through the removal of feeding cues, these behaviours were likely to be reduced, if not eradicated. Increasing the frequency of concentrate meals may be appropriate in this case, due the positive effects upon reducing the incidence of crib-biting.
A further association between concentrate feeds and stereotypical behaviours has been found in relation to stomach pH and gastric ulcers. As a result of the typical stable ration, the horse’s stomach can often become empty and can result in increased acidity (Freire et al, 2008). Oral stereotypies such as crib-biting may occur as a result of an attempt to buffer the acidity through the increased production of saliva (Nicol, 1999) or as a consequence of gastric ulcers (Nadeau et al, 2000). Gastric ulcers are particularly common in racehorses; studies reference between 66% (Hammond, Mason and Watkins, 2010) to 93% (Murray et al, 2010) are affected. Gastric ulcers occur through an imbalance of pH in the hindgut and have been linked to stressful situations such as weaning (Jones, 2002).
Research has suggested that the development of oral stereotypies may be as a result of a reduction in stomach pH due to the fermentation of grain in the hindgut. Methods of reducing acidity in the stomach have been investigated; Johnson et al (1998) measured the affect of the feed supplement ‘Founderguard’, containing the antibiotic Virginamycin, which aims to suppress lactic acid production in the hindgut. The study found a reduction in abnormal behaviours, including crib-biting and wood chewing, as well as a reduction in faecal pH. Furthermore, longer feeding times were shown by those fed with the supplement, although this may have been due to reduced palatability, this could however, have led to increased saliva production therefore contributing to the neutralisation of gut acidity.
Research has shown that up to 90% of horses in strenuous training and racing have gastric ulcers (Jones, 2002). Horses suffering from gastric ulcers tend to present with reduced appetite, poor body condition and weight loss (Kubiak, 2010). These symptoms are inline with the current case, and the horse has shown evidence of gastric ulceration of the squamous mucosa, however the client does not want to pursue medication as treatment due to the financial implications. Alternatively, the introduction of feed supplements such as Founderguard may be a more financially appropriate method of treatment in order to reduce the acidity. Additionally, changes to management have been show successful in controlling the effects of ulcers; increased access to forage is an effective way to reduce the symptoms and reduce the stomach acidity. Avoiding bucket feeding and instead placing the feed among a forage ration can increase the length of time spent eating, in turn increasing the saliva production. Increased turnout is an effective way to manage the disorder, however in this case the horse requires several months of box rest, followed by additional months spent in a small paddock, before being allowed into pasture full time.
In addition, there is thought to be a genetic factor influencing the onset of stereotypical behaviours; Waters et al (2002) found that foals of dominant mares showed a higher rate of behavioural problems than those from lower ranking mares. The direct casual link is unclear, however it is potentially as a result of genetics influencing behaviour, or perhaps due to the mare-foal bond and the subsequential end of their relationship through the weaning process. However, other studies have also aimed to determine whether genetic play a role in the development of these behaviours; Vecchiotti and Galanti (1986) aimed to determine the possibility of an hereditary aspect to the development of crib-biting, weaving and box walking in Thoroughbreds. The study found a potential genetic component in each of the stereotypical behaviours, however it was impossible to draw accurate conclusions from the results due to a lack of evidence. More recent research has investigated the potential for breed predispositions in the development of crib-biting. Albright et al (2009) found Thoroughbreds to have the highest rate of crib-biting than compared to Arabian, Warmblood and Quarter horse breeds. This supports prior research, Waters et al (2002) found 27% of Thoroughbreds in the study developed abnormal behaviour. It was here suggested that management for Thoroughbreds often involves rapid growth and development for early training for racing as 2 or 3 year olds. However, Albright et al (2009) stated that Thoroughbreds are not the only breed intensely managed and trained; Standardbreds, Warmbloods and Quarter Horses often compete in physically demanding e.g. racing and eventing, with similar management styles such as; spending large amounts of time in stalls and fed high concentrate meals. The high susceptibility to stereotypical behaviours may be due to the high reactivity levels of the breed (Mader and Price, 1980).
A further environmental factor contributing to the onset of stereotypical behaviours is the lack of contact with conspecifics. Stable environments often limit the amount of social contact available often due to the risks of negative social interactions (biting and kicking) and the subsequential risk of injury (Cooper and McGreevy, 2007). The social needs of the horse are often ignored by modern management methods and as social, herd animals, the effect of this can be detrimental to welfare (Hartmann et al, 2012). Research suggests that stereotypical behaviours such as weaving are a frustration response to decreased social contact in the stable environment (Nicol, 1999). Further research has found a link between social contact and stereotypical behaviours; McGreevy et al (1995b) found that visual contact of conspecifics significantly reduced the incidence of abnormal behaviours, in particular wood chewing which has known links to crib-biting. Cooper et al (2000) observed the effects of differing levels of visual contact between conspecifics on the incidence of weaving. The study found that increased visual contact through the opening of additional doors and grills between joining stables; no weaving behaviour was recorded when maximum visual contact was provided. The reduction in this behaviour was associated with increased contact with conspecifics, rather than through providing alternative views; opening a rear window without visual access through side grills had no effect upon weaving behaviour. This study highlights the importance of visual contact between conspecifics, in this case it may be necessary to provide the horse with greater visual contact in neighbouring stables as opposed to the current occasional contact from a nearby field.
Alternatively, if the addition of neighbouring conspecifics is not available, the use of stable mirrors has shown to be an effective way of reducing stereotypic weaving. McAfee et al (2002) found decreased incidence of the behaviour in several known weavers with the presence of a stable mirror. Although it is not known why the mirror reduces these behaviours, it is thought that it mimics visual contact with conspecifics or provides an environmental distraction to the horse. Regardless, the horses did not become accustom to the mirror and an increase in weaving behaviour throughout the study was not found. Furthermore, when the mirror was removed post-trial the incidence of the behaviour was lower than pre-trial. Therefore, this eliminates concerns of ‘rebound effect’, where unlike physical prevention of stereotypies such as the use of cribbing collars (Cooper and McGreevy, 2007), when removed the unwanted behaviours return with greater intensity, consequentially raising welfare concerns. The use of a stable mirror may be an effective, affordable and welfare ‘friendly’ method of reducing the incidence of behaviours in this case.
The method of housing is an important factor associated with the incidence of stereotypical behaviours; a study by Visser et al (2008) compared the effects of two different housing designs on the behaviour of young horses. The results found of those kept in traditional stables 67% displayed at least one stereotypy (weaving, box walking and cribbing) compared to none of the horses housed in pairs. Increasing social contact with conspecifics is suggested to decrease stress levels and in turn reduce the incidence of these unwanted behaviours (Cooper and McGreevy, 2007). However, the addition of a further horse into a stabled environment poses several issues; firstly if suitable paired housing designs are not readily available, this can pose financial implications. In addition, in this particular case, paired housing may not be suitable due to the potential for unequal feeding opportunities. Horse owner concerns in this area are high (Hartmann et al, 2012), and in particular regarding feeding horses for their individual nutritional requirements. The current horse presents as underweight and under-conditioned, therefore introducing another horse may impact the horse’s condition further.
Another aspect of housing management influencing these behaviours is the use of bedding type. Currently the horse is managed on a bed of shavings, however research has indicated that non-straw bedding is associated with the incidence of stereotypies, and weaving in particular (McGreevy et al, 1995b). The study suggested that through the eating of straw bedding the risks posed by low fibre diets may be reduced. Therefore, the use of straw bedding may help reduce the occurrence of weaving for this horse.
Conclusion
Horses needing box rest is a common requirement for the healing of a variety of disorders, however this is not practical for horses displaying stereotypies unless changes are made in order to reduce their incidence. Although research suggests there is no known cure for stereotypical behaviours, many methods have shown successful in minimizing their occurrence. In this case, a multitude of adaptions to management methods are suggested in order to reduce the prevalence of the behaviours in order to aid the successful healing of the FOOT throughout the box rest period. These include; greater social contact with conspecifics or a stable mirror, an increase in the amount of forage provided, an increase in the frequency concentrate meals with low levels of noise to reduce the anticipatory response, the addition of feed supplement (Founderguard) to help manage stomach pH and gastric ulcers, and the use of straw bedding. As result, the prevalence of these behaviours should be reduced and the potential for full a recovery and future 24 hour turnout is possible. Making these adaptions rather than methods of physical prevention, the welfare of the horse will be improved considerably, and should eliminate any risk of the rebound effect following box rest. These changes have shown to be successful in reducing the incidence of these behaviours, without the additional stress and frustration of physical preventative methods