Fence Walking

I've posted this several times on COTH and now I'm just going to put it here to direct people to. This is from an assignment for my Equine Behaviour and Welfare class last spring. We had to do a poster about an equine stereotypy. I picked fence walking as Banana does it. While this assignment was on fence walking, most of the information applies to the other stereotypies (like crib-biting) as well.

Abstract
Stereotypies are triggered by the modern stable environment. Caused by denying the horse its behavioral needs, factors such as genetics, weaning style, and riding style create a horse primed to be more bothered by the restrictive situation. Fence and stall walkers tend to be less tolerant of restrictive housing. Through neurologic changes, stereotypies can be a lifetime affliction.

Introduction
Fence walking, also known as stall or box walking when in a more enclosed space, is a locomotor stereotypy. It has not been studied as in depth as that of other stereotypies, such as crib biting. However, the basic causes of all stereotypies are from the same source: restrictions of the horse from engaging in its behavioral needs.

Epidemiology
The walking stereotypies (fence, stall, box) involve frequent movement of the horse along the perimeter of the confinement, whether in a circle in a stall, or back and forth along a fence. The horse can prefer this activity over eating or resting, resulting in loss of body condition, excessive hoof wear and orthopedic problems. It also causes untidiness of the stall, as urine and feces are mixed into the bedding, or a worn area next to a fence.

In nature horses move and forage constantly with conspecifics. When humans moved horses into the stable environment these activities were then forbidden the horse by confinement and management styles and stereotypies appeared. A box for every single horse, and meals two times a day, appeals to the owner, but not to the horse. Equine stereotypies don't seem to have a function from the human's perspective, but research suggests it is a form of coping with the stress of the unnatural captive environment they have been placed in and are not suited to (McBride and Hemmings, 2005).

Causality

Primary factors

• Restrictive housing - Normando et al. (2001) found horses in restrictive stabling were more likely to show locomotor stereotypies, like fence walking, than those in freer conditions. Horses stalled more and pastured less are at a higher risk for stall walking (Luescher et al., 1998, Bachman et al., 2003).
• Restrictive companionship - horses allowed minimal physical and visible contact with other horses have a greater amount of abnormal behavior. (Bachmann et al, 2003, McGreevy et al, 1995).
• Restrictive diet - In a stable environment the horse is fed meals. The restriction of foraging behavior (Winskill, 1995) and the addition of concentrates into the equine diet that reduced eating time (Luescher et al., 1998) conflicts with the horses' natural eating practices. McGreevy et al. (1995) found that feeding forage three times per day increased stereotypies, while feeding four or more times reduced it.

Secondary factors

• Weaning style - Foals that are separated and put into barns are more likely to develop stereotypies than those placed in pasture groups. Waters et al. (2002) found box walking was initiated in 2.3% of their study group at the median age of 64 weeks.
• Reactivity - Bachmann et al. (2003) found horses assessed to be reactive by their owners to be twice as likely towards stereotypy.
• Genetics - Vecchiotti and Galanti (1985) found that incidences of stereotypy were much higher in families with a history of the behavior. The incidence of stall walking in the greater group was 2.5%, but it was 13% in families with a history of it. However, it could be that the genetic component made a more nervous horse, more likely to engage in stereotypy than that the stereotypy itself is genetically based. They found a case of a stallion who was known to be nervous and a stall walker. In his progeny of 76 horses, 47 (62%) were also nervous and 11 (15%) also stall walked.
• Breed - Luescher et al. (1998) found Arabians were more likely to stall walk at 7.32%, as opposed to Thoroughbreds at 3.03%, and Standardbreds at .59%. Bachmann et al. (2003) found increased odds in Warmbloods (1.8) and Thoroughbreds (3.1) compared with other breeds.
• Style of riding - Horses ridden English are more inclined towards stereotypy (Normando et al., 2011), however they were also more likely to have restrictive stabling. McGreevy et al. (1995) found the rate of box walking higher in endurance horses, but many of those horses were Arabians.
• Age - Prevalence of stall walking increases with age (Luescher et al., 1998). Bachmann et al (2005) found horses under four years of age had almost four times lower odds of performing stereotypies in comparison to mature horses.

Neurologic aspects
In the beginning, a fence walker walks, trying to achieve the goal of getting to forage or companionship on the other side of the fence. This is the appetitive phase of goal seeking. Alas, the fence itself prevents the horse from ever reaching its goal, known as the consummatory phase. While in the appetive phase dopamine transmission between the VTA and neuro accumbens increases along the mesoaccumbens pathway. For some horses lack of goal attainment does not weaken the horse's desire, but increases it, turning the behavior into a repetitive loop and in the case of stall walking an actual, literal loop. More activity in the mesoaccumbens pathway makes for a more motivated horse and prolonged stereotypy from stress can alter the dopamine pathway physiology (McBride and Hemmings 2005).

Attenuation approaches
Laymen will suggest tying the horse to prevent fence or stall walking, but this does not eliminate the behavior and could result in the horse instead turning their locomotor needs to weaving. McBride and Cuddeford (2001) found that stereotypy may have a coping function and denying the horse the behavior could have welfare implications.

The owner must decrease the stress in the horse's life to decrease the stereotypy.

• Reduce the restrictions on behavioral needs - allow the horse constant forage, large spaces to move in, and companionship.
• Adapt the indoor environment - McGreevy et al. (2005) found the giving sufficient amounts of forage and hay alternatives, visual contact with conspecifics (such as with bars between stalls), and an active stable yard reduced stereotypies. McAfee et al. (2002) found that the reflection of the horse in a mirror could minimize separation stress. Adding a forage device like the modified "Edinburgh Foodball" used by Winskill et al. (1995) increased foraging time and decreased standing time.

Even with optimal living arrangements, the horse may not discontinue the activity. A fence walker turned out in a large grass pasture with companionship may still pace the fence. Once stereotypies are developed they can be difficult, if not impossible, to remove, possibly due to altered dopamine physiology in the brain (McBride and Hemmings, 2005). The best tactic is to ensure the horse is not in an environment with stereotypy producing factors present from the very beginning.

Conclusion
What many label as an activity of boredom, equine stereotypies are in actuality the horse's response to a stressful environment. Care should be taken to keep horses out of living situations in which behavioral necessities are denied, preventing the neurologic changes that come from a chronic source of stress. For fence and stall walkers removal from the restrictive housing environment may be the most important, but all of the primary factors should be considered.

References
Bachmann, I, Audigé, L, & Stauffacher, M. (2003) 'Risk factors associated with behavioural disorders of crib-biting, weaving and box-walking in Swiss horses',  Equine Veterinary Journal, 35(2), pp. 158-163.

Luescher, U, McKeown, D, & Dean, H. (1998) 'A cross-sectional study on compulsive behaviour (stable vices) in horses', Equine Veterinary Journal. Supplement, 27, pp. 14-18.

McAfee, L, Mills, D, & Cooper, J. (2002) 'The use of mirrors for the control of stereotypic weaving behaviour in the stabled horse', Applied Animal Behaviour Science, 78(2-4), p. 159.

McBride, S, & Cuddeford, D. (2001) 'The putative welfare-reducing effects of preventing equine stereotypic behaviour', Animal Welfare, 10(2), pp. 173-189.

McBride, S, & Hemmings, A. (2005) 'Altered mesoaccumbens and nigro-striatal dopamine physiology is associated with stereotypy development in a non-rodent species', Behavioural Brain Research, 159(1), pp. 113-118.

McGreevy, P, Cripps, P, French, N, Green, L, & Nicol, C. (1995) 'Management factors associated with stereotypic and redirected behaviour in the thoroughbred horse', Equine Veterinary Journal, 27(2), pp. 86-91.

Normando, S, Meers, L, Samuels, W, Faustini, M, Ödberg, F. (2011) 'Variables affecting the prevalence of behavioural problems in horses. Can riding style and other management factors be significant?', Applied Animal Behaviour Science, 133, pp. 186-198.

Vecchiotti, G, & Galanti, R. (1986) 'Evidence of heredity of cribbing, weaving and stall-walking in thoroughbred horses', Livestock Production Science, 14, pp. 91-95.

Waters, A, Nicol, C, & French, N. (2002) 'Factors influencing the development of stereotypic and redirected behaviours in young horses: findings of a four year prospective epidemiological study', Equine Veterinary Journal, 34(6), pp. 572-579.

Winskill, L, Waran, N, & Young, R. (1996) 'The effect of a foraging device (a modified 'Edinburgh foodball') on the behaviour of the stabled horse', Applied Animal Behaviour Science, 48(1-2), pp. 25-35.