- Definition
- Pathophysiology
- Systems Affected
- Genetics
- Incidence/Prevalence
- Geographic Distribution
- Signalment
- Signs
- Causes
- Risk Factors
BASICS
- A stereotypic behavior is a relatively invariant, repetitive pattern of movement with no obvious purpose
- It arises from a thwarted normal maintenance behavior (walking), but is performed excessively and out of context to the exclusion of normal behaviors, and so is a welfare concern
- Equine locomotor stereotypic behaviors include stall/box-walking; weaving; fence running
- Weaving consists of an obvious lateral swaying movement of the head, neck, forequarters, and sometimes hindquarters, with the limbs typically tensing in the sequence of the walk or trot, even if the animal does not move forward (see Web Video 1). The horse may toss, nod, and shake its head at the same time, but this should not be confused with the separate condition of headshaking syndrome
- Unclear but appears to relate to motivational conflict
- Proposed mechanisms implicate serotonergic and dopaminergic systems, but there is no evidence of dysfunction
- Behavioral—may interfere with expression of normal maintenance behaviors or with performance of learned responses
- Musculoskeletal—uneven hoof wear or muscle development
- Decreased performance if the behavior is performed to the point of fatigue or self-injury but this is rare
A genetic predisposition is suspected, but the precise nature of inheritance has not been determined.
Weaving occurs in about 3% of horses but the prevalence varies with circumstances (range 0–10%). For stall-walking average prevalence is around 2% (range 0–7%).
- No age or sex predilection, but the occurrence of 1 locomotor stereotypic behavior increases the risk of another
- Warmbloods and Thoroughbreds are at a general increased risk of developing stereotypic behaviors
- More common among endurance horses and horses with reduced or restricted exercise (<1.5 ha), especially if kept in face-to-face stalls, where locomotion is likely to be frequently thwarted as they try to interact with horses opposite
- Median age of onset is 64 weeks for weaving and 60 weeks for box-walking
- Time spent performing the behavior varies. The behaviors are often elicited by arousal associated with a desire to engage with stimuli outside the stall (e.g. food or other horses being led to and from barns or pastures, toward or away from herd mates; or in anticipation of pleasurable experiences outside the stall). The intensity of the behavior may increase at times of increased emotional arousal
- Stall-walking—circular pacing when confined to a stall. The horse may circle in 1 or both directions, repeatedly tracing its path, sometimes even placing its feet in exactly the same place during each circuit
- Weaving—rhythmic side-to-side swaying of the head and neck, often accompanied by an obvious alternate stepping in place with the front limbs and possibly all 4 limbs to the beat of the walk or trot
- Fence running—the horse walks, trots, or canters in a repetitive pattern along a fence line or before a gate, with the distance traveled and the location and features of the turns being the same each time
- Head nodding, tossing, and shaking as well as kicking out at the stall walls or door may also occur with any of these locomotor behaviors
Owners may report a gradual onset or an inciting event after which the behavior was seen to become more obvious.
Environment and management practices that inhibit expression of locomotion or locomotor expectations (e.g. periods of extensive exercise followed by periods of enforced rest).
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS