Stereotypical behaviour describes repetitive, ritualised, out-of-context locomotor behaviour, such as pacing, circling, or shuffling.
Compulsive behaviour was introduced to capture behaviours related to stereotype behaviour, but that are non-locomotor (vocalisation, licking, self-mutilation, staring, holding an object or part of body, staring into space). Today the term compulsive disorder is used as a general term for all the behaviours in this class1, 3, 6, 8.
Compulsive disorder (CD) describes a sequence of movements usually derived from normal maintenance behaviours that are performed out of context in a repetitive, exaggerated, ritualistic and sustained manner. They must be sufficiently pronounced to exceed what is necessary to meet its apparent goal or such that it interferes with normal functioning2, 3, 6.
When discussing compulsive disorders terms such as conflict induced behaviour, frustration induced behaviour, displacement behaviour, redirected behaviour and vacuum activity are commonly used.
Below is a short definition of the terms:
Conflict induced behaviour: The presence of two opposing, similarly strong motivations at the same time. This may lead to a displacement behaviour1, 3, 8.
Frustration induced behaviour: A situation where an animal is motivated to perform a behaviour but is prevented from doing so because of physical or psychological obstacles in the environment. The resultant behaviour could be a displacement behaviour or a redirected behaviour1, 3, 8.
Displacement behaviour: A normal behaviour shown at an inappropriate time and appearing out of context for the occasion. It may be observed in situations of arousal when there is no appropriate outlet for arousal3.
Redirected behaviour: The animal is motivated to perform an activity but is unable to gain access to the principle target. The behaviour is directed to an alternative target3.
Vacuum activity: An animal may be highly motivated to perform an instinctive behaviour but there is no available outlet. These activities have no apparent useful purpose3.
Development of Compulsive Disorders
Compulsive disorders initially originate from behavioural arousal, stress, conflict and frustration, which can lead to anxiety or displacement behaviours. Arousal and anticipation are physiological states that are vital to normal behaviour and are linked to anxiety and normal expectations of reward. When an animal anticipates a positive outcome and the outcome is less rewarding or never happens, frustration is the result. When an animal anticipates threat or danger, there is a negative emotion which is unpleasant and leads to anxiety. Frustration and fear are essentially the same emotional state in animals. Both anticipation of a threat or danger and the anticipation of frustrated non-reward are therefore negative emotional experiences involving anxiety1.
There appear to be at least two different mechanisms by which compulsive disorders arise.
Locomotor CD (tail chasing, pacing) tend to develop in situations of stress, anxiety, conflict or frustration and tend to be displayed in situations of high arousal.
Oral and self-directed CD (licking) may develop more acutely without any obvious conflict, and are most likely displayed in situations of minimal stimulation. They may even help to calm the pet3.
Possible etiologies for a compulsive disorder might include3.:
- Insufficient stimulation
- Changes in routine
- Inconsistent or improper training
- Anxiety inducing situations
- Household changes, including change in family members or pets
- Situations of conflict or frustration
Compulsive behaviour appears to develop when the animal discovers that multiple repetitions of a ritualised behaviour produces a reduction in arousal and frustration. The behaviour provides a faster, more reliable, and more effective escape from the negative emotions. The experience of reduction of arousal rewards the behaviour, reinforcing it.
Compulsive behaviours generalize to other contexts in which the animal experiences a high level of arousal. As the number of eliciting contexts increase, the threshold of arousal needed to elicit the compulsive behaviour decreases and the animal appears to lose the choice whether to perform the behaviour or not4. Any attention from owner inadvertently reinforces the behaviour.
There is a thought that compulsive behaviour may be self-reinforcing, caused by the release of endogenous opoids in the CNS, which may allow some animals to cope with conditions that don’t meet their species-specific needs. This theory however lacks scientific support through research2.
Compulsive behaviours can be classified in groups.
- Behaviours involving locomotion: spinning, tail chasing, pacing
- Oral behaviours: self-licking/chewing, flank sucking, pica, licking/chewing of objects
- Vocalisation: howling, barking
- Hallucinatory behaviours: staring at shadows, fly snapping, air licking
- Aggressive behaviours: aggression directed at inanimate objects or towards self
Malfunctional vs. Maladaptive
Compulsive behaviours are abnormal as they are displayed out of context and are repetitive, exaggerated or sustained3. Captive animals however, controversy as to whether CD represent a normal response of a normal animal to an abnormal environment (maladaptive) or whether they are abnormal in the sense of lacking in function and/or being the expression of an underlying pathology (malfunctional)3. In maladaptive behaviours the animal attempts to find a surrogate for a missing normal behaviour, to escape from confinement or to otherwise alleviate a problem. They are abolished immediately by a specific change in husbandry. Malfunctional behaviours are a product of pathology, may occur with a range of other effects and may involve source behaviours that do not closely reflect the original cause of repetition5, 7.
The age of onset of compulsive behaviours normally correlates with social maturity with a median age of onset of 12 months. Male dogs over represented and there appears to be a genetic predisposition. The type of compulsive disorder may be affected by breed. Examples of breed specific compulsive behaviours include:
- Bull terriers: tail chasing
- Doberman pinchers: flank sucking
- Border collies: chasing of shadows
- Large breed dogs: acral lick granuloma
Behaviour to gain attention can look similar to compulsive disorder. Dogs can simulate medical signs and display other behaviours that get a response from the owner. Attention (albeit negative) from the owner reinforces the behaviour. Negative attention increases dog’s anxiety and the need for further reassurance. This kind of attention seeking only occurs when owner is present but not directly attending to the dog. Compulsion arising from hyper-attachment (separation anxiety) causes behaviour when owner is unable to attend to the dog, including times when they are away, and is therefore different from attention seeking behaviour.
Diagnosis and Assessment
Compulsive behaviour is a diagnosis by exclusion. Attention seeking behaviours as well as neurological and medical disorders can produce similar signs and these must be excluded. Seizure foci differ from compulsive disorders in that seizures arise independent of any specific stimuli or events, do not occur with any degree of regularity or predictability, cannot be interrupted, may have a recognizable pre-and/or postictal phase and often improve with anticonvulsant therapy3.
The dog usually shows a normal level of awareness throughout the behaviour (vs epilepsy, cognitive impairment)3. It may be difficult to interrupt the behaviour and the dog may become aggressive if it is manually restrained. The dog shows normal behaviour inbetween bouts. There is a sudden and abrupt transition to compulsive disorder, without indicator signs.
The severity of behaviour is defined by several criteria. These include:
- Ease of interrupting the behaviour
- The number of different contexts in which the behaviour occurs
- Different or more than one event/stimuli which trigger behaviour
- The amount of time spent in compulsive behaviour, and the degree that it substitutes for normal behaviour
- Progression of the behaviour
Dogs that show compulsive behaviours in multiple contexts, with the behaviour substituting for a number of normal behaviours and being difficult to interrupt, are seriously affected.
Acral Lick Granuloma and Tail Chasing
Figure 1A & B: Metatarsus of a Great Dane with a chronic ALG The severe inflammatory response has caused a periosteal reaction on the underlying bone (Photo courtesy L vd Merwe OVAH)
Acral lick granuloma (ALG) is a distinct clinical entity in which dogs lick one or more of their limbs, causing significant damage. There are raised, ulcerative, firm plaques usually located on the limbs, most often the carpus and metacarpus2 (Fig 1). Large breed dogs are most commonly affected. Lack of stimulation is frequently cited as the cause, but the licking may also be a displacement behaviour arising out of situations of conflict, frustration or anxiety. The behaviour occurs both when the owner is present and may occur at an even higher rate when the owner is absent. Underlying anatomical abnormalities (arthritis, fracture, neural entrapment) or infectious or inflammatory causes may contribute this behaviour3.
Tail chasing or spinning describes the behaviour where an animal spins in tight circles apparently trying to catch its tail. Some animals make contact with their tail and injure it, while others just go through the chase sequence. The tail chasing may occur in times of stress, frustration and conflict2.
Since compulsive disorders are both debilitating and progressive, it must be treated aggressively from the start. A multi-modal approach should be used. Medical treatment must be provided for self-inflicted trauma (ALG and tail chasing). Early social experience prevents all kinds of anxiety disorders. Puppies that are used to living in sociable and complex domestic environments are attracted to novelty and they are used to periods of solitude. This reduces the risk of behavioural problems. The dog has learnt to cope with a normal range of stimulation, arousal, frustration and behavioural conflicts.
For ALG management would include the prevention of licking to allow for healing (Elizabethan collar, bandage, or even limb amputation), but this is not a long-term solution as it does not address the underlying behavioural pathology. Many dogs will start licking another limb if the effected limb is bandaged. For the same reason, there is no place for tail amputation in tail chasing, unless it is to address secondary infection and trauma. Tail amputation does not treat the underlying motivation and the dog will still spin even if the tail is amputated.
Routines that create profound sense of order must be put in place (feeding, training, exercise and playing). Routines help create a predictable environment and decrease anxiety. The environment must be made more engaging so that time and energy budget are used up constructively. Food dispensing toys that encourage interaction with the toy and are preferred. The animal must be provided with a quiet and calm refuge or resting place. The dog’s level of mental and physical activity should be increased. Stress can be reduced by creating a predictable environment for the pet. This can be achieved by including daily scheduled exercise, social interactions and play2.
The owners must make a detailed list of all stimuli that trigger the behaviour (doorbell, telephone, visitors, owner departure, and excitement). Where possible, exposure to these triggers must be avoided or reduced. Training involves that each stimuli that triggers the unwanted behaviour is associated with a rewarded performance of another behaviour (response substitution) or to counter condition the emotional response to it. The pet can be taught to be calm, settled and relaxed on cue in a specific location2. The trained calm behaviour can be associated with each of the stimuli and contexts that provoke the behaviour. The client must be discouraged from reassuring the patient during stressful events as this can lead to attention seeking behaviour. There is no place for punishment and threats (scolding, smacking). Owners must be cautioned against physical intervention during a compulsive bout, as it may trigger redirected aggression, putting the owner at risk of being bitten.
Drugs are indicated for cases where the condition is severe, longstanding or where the behaviour is difficult to interrupt. It should also be considered when progression is rapid and the situation continues to worsen. They must be used in combination with behavioural therapy and environmental management. It is a way to reduce the inflexibility and rate of expression of compulsive behaviours so that environmental change and behavioural modification can be more effective.
Clomipramine and fluoxetine are commonly used1. Tricyclics, other than clomipramine, or merely anxiolytic drugs are unlikely to have an effect because they have much weaker effect on serotonin re-uptake and because compulsive behaviour, once well established, can be performed even when the animal is not in a high state of anxiety4.
The thought is to start with a selective serotonin reuptake inhibitors (SSRI). If there is failure to respond, switch to another SSRI or change to clomipramine1. Dose rates are generally a little higher for compulsive disorders. Treatment is usually started at the lower end of the dose range. If there is some improvement, but not sufficient, the dose is increased but it is better to switch to another drug if there is poor initial response1.
Drugs used for ALG include clomipramine and selective serotonin reuptake inhibitors. It may take months of therapy before the lesions resolve. Doxepin and amitriptyline (both TCAs) might be useful as they have behavioural and antihistaminic effects, but they generally do not have sufficient effect on the serotonin re-uptake to be as effective as clomipramine3.
Drug dose rates are3:
- Clomipramine: 2 – 3 mg/kg BID
- Fluoxetine: 0.5- 2 mg/kg OID
- Amitriptyline: 1 – 2 mg/kg BID
- Gabapentin: 2- 5 mg/kg BID
Tricyclic antidepressants are generally well tolerated in healthy dogs but there might be some side effects. Mild sedation is common, especially during the first week of treatment. There may by anticholinergic (dry mouth, fecal and urinary retention) and antihistaminic side effects. Cardiac conduction disturbances may occur in predisposed animals, necessitating appropriate cardiac assessment prior to administration. Cardiac effects appear to be benign when the drug is administered at therapeutic doses to healthy dogs. TCA’s may lower seizure threshold. The onset of side effects may be immediate1. The side-effects of SSRIs include GI irritation, sedation, insomnia and irritability. There are virtually no cardiovascular side effects. GI effects include anorexia, inapperene, nausea or diarrhoea. Side effects may be avoided by gradually increasing the dose.
Medication is often life-long but is some cases the drug dosage can be decreased or stopped completely. The thought is that treatment should continue at least for twice as long as what it took to reach a sufficient decrease in signs. For example, if it took 8 weeks for the dog to stop chasing its tail, the dog should be on the drug for at least another 16 weeks. The owners should be warned to not just stop giving the medicine, the dose should be gradually reduced. A rebound effect may occur when the drug is abruptly stopped, giving rise to worse symptoms that what the dog had before medication was started. The dog should be gradually weaned off the drug, a guideline being one week for every month of treatment. This means that if the dog was on the drug for 6 months, it should be tapered off over a 6 week period.
The owner must be informed that it may take weeks to see an improvement. Intermittent relapses are common. Control, rather than cure, is a realistic expectation. There is a poor prognosis for dogs that continue to live in stressful or deprived environments.
- Bowen, J. and Heath, S. 2005. Behaviour problems in small animals, p 97-108; 177-184. Elsevier Saunders, Edinburgh, UK.
- Horwitz F.D. and Neilson J.C. 2007. Canine and Feline behavior, p 227-235. Blackwell Publishing, Iowa, USA
- Landsberg, G. Hunthausen, W and Ackerman, L. 2003. Handbook of behavior problems of the dog and cat. 2nd Edn, p 195-225. Elsevier Saunders, London.
- Leuscher, A.U. Compulsive behaviour. In: Horwitz, D; Mills, D. and Heath, S (eds). 2002. BSAVA manual of canine and feline behavioural medicine, p 229-236. British Small Animal veterinary Association, Gloucester, UK.
- Mason, G. Stereotypic behaviour in captive animals: Fundamentals and implications for welfare and beyond. In: Mason, G. and Rushen, J. (eds). 2006. Stereotypic animal behaviour: fundamentals and applications to welfare. 2nd edn, 325-356. CAB International, Wallingford, UK.
- Mills, D.M. Compulsive disorder. In: Mills, D.S (editor in chief). 2010. Encyclopedia of applied animal behaviour and welfare, p 121. CAB International, Oxfordshire, UK.
- Mills, DS and Luescher, A. Veterinary and pharmacological approaches to abnormal repetitive behaviour. In: Mason, G. and Rushen, J. (eds). 2006. Stereotypic animal behaviour: fundamentals and applications to welfare. 2nd edn, 286-324. CAB International, Wallingford, UK.
- Overall, Karen. 1997. Clinical behavioural medicine for small animals, p 209-249. Mosby, St Louis.
- Würbel, H. Stereotypies. In: Mills, D.S. (editor in chief). 2010. Encyclopedia of applied animal behaviour and welfare, p 575-578. CAB International, Oxfordshire, UK.