Manteca X. BVCE 94 [2], n°3, 4 - 22-26
STEREOTYPICAL BEHAVIOR IN DOGS
INTRODUCTION
Stereotypical behavior have long been recognized in
dogs and include disorders such as fly biting, tail chasing, acral lick
dermatitis, self-mutilation and compulsive pacing or barking (Overall,
1992a). Many of these disorders can be very annoying to the owner and
some of them may also result in the dog inflicting damage to itself.
Further, treatment efforts are often disappointing and this is partly
due to our poor understanding of the underlying etiology.
TERMINOLOGY
Stereotypies are defined as unvarying, repetitive
behavior patterns that have no obvious goal or function (Mason, 1993).
The term therefore refers to the appearance of the behavior, regardless
of its cause. Recently, the term obsessive-compulsive disorder (OCD)
has been used to refer to behavioral abnormalities of companion animals
that fall into the category of stereotypical behavior (e.g. Overall,
1992a) The term OCD is applied in human medicine to stereotypical
behavior caused by an alteration in the metabolism of serotonin and
endogenous opioids (Rapoport, 1988). In this paper, the term
stereotypical behavior will be used to refer to any unvarying,
repetitive behavior that having no obvious function interferes with the
normal activity of the animal. The term OCD will be used only to refer
to those stereotypical behavior that are likely to be a result of an
alteration in the metabolism of serotonin and endogenous opioids (this
is usually found out on the basis of the animal's response to
treatment).
SUGGESTED PLAN FOR DIAGNOSIS
As with other behavioral problems, the first step when
attempting to make a diagnosis is to ascertain whether the condition
has been caused by a medical problem. If the dog can be easily
distracted from performing the stereotypical behavior and exhibits it
only in certain circumstances, it is unlikely to have a medical cause.
Alternatively, if the dog can not be distracted from performing the
stereotypical behavior and engages in it under a variety of
circumstances, it is likely that the condition results from a medical
problem (Crowell-Davis, 1992). However, it has to be emphasized that
behavioral disorders resulting from medical causes may be responsive to
environmental changes and therefore the above criteria are not always
safe (e.g. Crowell-Davis et al., 1988).
Consequently, the occurrence of any other clinical sign during general examination is also an important criterion. Further, if the practitioner is familiar with the medical conditions that are most likely to cause such problems, he or she may be able to use ancillary techniques aimed at diagnosing such conditions.
Medical problems that can cause stereotypical behavior The term psychomotor epilepsy refers to the occurrence of bizarre behavioral activity such as stereotypical behavior with or without motor seizures and due to diseases affecting the limbic system and/or the temporal lobe (Sorjonen, 1992).
Theoretically, if psychomotor seizures are the cause of the stereotypical behavior, anticonvulsive therapy should ameliorate the symptoms. However, response to such therapy if often difficult to evaluate in animals showing behavioral disorders only and this makes the diagnosis more difficult.
Diseases causing psychomotor seizures include, but are not restricted to, lead poisoning, canine distemper virus encephalomyelitis, trauma, tumor, thromboembolic disease and hepatic encephalopathy (Sorjonen, 1992). In lead poisoning, dogs usually have circulating nucleated red blood cells and basophilic stippling without marked anaemia. Also, radiopaque densities may be present in the intestinal tract (Sorjonen, 1992). Blood work is equally useful to decide whether hepatic encephalopathy is the cause of the behavioral disturbance and the most common findings are described elsewhere (Chrisman, 1991).
Cerebrospinal fluid analysis can help establish a diagnosis of canine distemper virus infection. In affected animals, cerebrospinal fluid analysis typically reveals 15 to 60 white blood cells per cubic millimeter that are predominantly mononuclear. The presence of neutralizing antibody to canine distemper virus in cerebrospinal fluid is the most definitive evidence of a patent canine distemper virus infection (Sorjonen, 1992).
Trauma, tumor and thromboembolism of the brain are conditions that less frequently produce psychomotor seizures. A detailed anamnesis, radiographs -including survey radiographs of both thoracic and abdominal cavities- and neuro-imaging techniques such as computed tomography and magnetic resonance imaging are most helpful to establish a diagnosis (Sorjonen, 1992).
Conditions other than psychomotor epilepsy can also cause stereotypies. These include diseases caused by tick-borne pathogens and therefore blood work and bone marrow biopsies may be useful (Overall, 1992b). In animals showing tail chasing, intervertebral disk disease must always be considered as a possible cause (Chrisman, 1991). If self-mutilation is the problem, dermatological conditions and alteration in peripheral nerve function, among other problems, should be taken into account (Chrisman, 1991).
If all the above possibilities are ruled out, the problem either has no medical cause or is an OCD. Stereotypies with no organic etiology can result from anxiety or be learned conditions. Learned and anxiety-induced stereotypies. Stereotypies can result -or at least can be perpetuated- by the owner unconsciously reinforcing the behavior. Particularly if the dog gets little attention at all, whatever the owner does to the dog to stop it performing the stereotypy may become a reward and, through operant conditioning, the frequency of the behavior will increase. If this is the case, the stereotypy can become an attention-getting behavior. When this is suspected to be the case, treatment must always include advising the owner to ignore the dog when it engages in the stereotypical behavior and rewarding it when performing other activities (Hart & Hart, 1985).
Stereotypies can also result from fear and anxiety, and pharmacological treatment using anxiolytic drugs such as buspirone (1 mg/Kg PO q 24 h) can be useful in these cases. Side effects include mild disorientation and GI symptoms. If the animal is suffering from separation anxiety, amitriptyline is the drug of choice. Care should be taken to make sure that the animal is not suffering from glaucoma, cardiac arrhythmias or hepatic or renal disease. An initial doses of 1.5 mg/Kg PO q 12 h during 3-4 days is recommended. If the condition does not improve, the doses can be doubled and administered for 3-4 further days. If there is no response either, treatment must be discontinued. If the drug proves to be useful, treatment should continue for at least 2-3 weeks and then be gradually interrupted (Overall, 1992b).
If neither advising the owner not to reinforce the behaviour nor anxiolytic drugs ameliorate the problem, the dog is likely to be suffering from an OCD. Clomipramine has been successful in the treatment of human OCD and, although not a panacea, is also useful in some dogs with stereotypies that do not respond to any of the above treatments. It seems to be particularly successful in animals with a sudden onset of the problem and with no previous history of stereotypies. The dosage used is as follows: 1 mg/kg PO q 12 h for 2 weeks, then 2 mg/kg PO q 12h for weeks 3 and 4, then 3 mg/kg PO q 12h through week 8. The final dosage is not recommended to exceed 200 mg per day. This guideline is intended to minimize the cardiotoxic effects of clomipramine (Overall, 1992b).
CONCLUDING REMARKS
When confronted with a problem
of stereotypical behaviour in a dog, the first step in any diagnosis
plan should be to rule out organic problems as a cause of the
behavioral abnormality. Once this has been done, treatment should
include advising the owner not to reinforce the behaviour and giving
anxiolytic drugs to the dog. If any particular stressor is suspected to
be the cause of the problem, trying to remove it would be obviously
helpful. When all this does not have any success, the possibility of
the animal having an OCD should be considered and it is then suggested
to treat the dog with clomipramine.
REFERNCES
Chrisman, C. L. (1991). Problems in small animal neurology. Lea & Febiger, Philadelphia.
Crowell-Davis, S. L. (1992). Tail chasing in dogs. In: Current Veterinary Therapy XI. Eds R. W. Kirk and J. D. Bonagura. W. B. Saunders, Philadelphia. pp 995-997. Crowell-Davis, S. L.; Lappin, M. & Oliver, J. E. (1989). Stimulus-responsive psychomotor epilepsy in a Doberman pincher. Journal of the American Animal Hospital Association 25: 57-60.
Hart, B. L. & Hart, L. A. (1985). Canine and feline behavioral therapy. Lea & Febiger, Philadelphia.
Mason, G. J. (1993). Forms of stereotypical behaviour. In: Stereotypical animal behaviour: fundamentals and applications to welfare. Eds A. B. Lawrence and J. Rushen. CAB International, Wallingford. pp 7-40.
Overall, K. L. (1992a). Recognition, diagnosis and management of obsessive-compulsive disorders. Part 1: a rational approach. Canine Practice, 17 (2): 40-44.
Overall, K. L. (1992b). Recognition, diagnosis and management of obsessive-compulsive disorders. Part 2: a rational approach. Canine Practice, 17 (3): 25-27.
Rapoport, J. L. (1988). Neurobiology of obsessive compulsive disorders. Journal of the American Medical Association, 260: 2888-2890.
Sorjonen,
D. C. (1992). Psychomotor seizures in dogs. In: Current Veterinary
Therapy XI. Eds. R. W. Kirk and J. D. Bonagura. W. B. Saunders,
Philadelphia. pp 992-995.