TERMINOLOGYStereotypes 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 behaviors (e.g. Overall, 1992a) The term OCD is applied in human medicine to stereotypical behaviors 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 behaviors 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
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 behaviors The term psychomotor epilepsy refers to the occurrence of bizarre behavioral activity such as stereotypical behaviors 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 behavior 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).
When confronted with a problem of stereotypical behavior 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 behavior 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.
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