| Anxiolytics, antipsychotics, antidepressants, and mood stabilizers used to treat human behavioral disorders are being used more commonly in veterinary medicine as adjuncts to behavioral modification therapy (see also
principles of pharmacologic treatment,
Principles of Pharmacologic Treatment). Few veterinary clinical studies have been reported, and guidelines for veterinary use are grounded on therapeutic applications in human medicine. |
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Anxiolytics, including the benzodiazepines and an azapirone (buspirone), have been used to treat generalized anxiety and panic disorder in humans. Diazepam has been recommended to alleviate fear-related behaviors in animals, eg, thunderstorm anxiety in dogs and social anxiety in cats. However, benzodiazepines may not alleviate fear-related aggression in certain animals, but instead may cause a
paradoxical increase in such behaviors. Diazepam has been reported to diminish urine-spraying behavior in cats, although most cats resumed urine spraying when the drug was withdrawn. Additional reported usages for diazepam include taming effects on wild animals, correcting sleep disorders in dogs, and stimulating appetite in cats. Diazepam, clonazepam, and chlorazepate dipotassium also have antiepileptic properties (see
Anticonvulsants) and may be useful in treating behaviors based on nonconvulsive seizures. Buspirone differs from the benzodiazepines in pharmacologic properties, ie, basis of receptor interactions, delayed onset of antianxiety effect (≥1 wk), and lack of sedative effect. Buspirone appears to offer no greater control for anxiety-related behaviors than the benzodiazepines. |
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Antipsychotics are classified as low-potency agents (acepromazine, chlorpromazine, and thioridazine hydrochloride) and high-potency agents (haloperidol, fluphenazine, trifluoperazine hydrochloride, prochlorperazine, thiothixene, risperidone). Low-potency agents are administered at dosages of 1-3 mg/kg and have side effects of sedation, anticholinergic effects, and α-adrenergic blockade. The high-potency agents are administered at dosages of 0.5-1.0 mg/kg and result in less sedation and fewer autonomic side effects but commonly result in extrapyramidal effects
of parkinsonism, dystonia, dyskinesia, and akathisia. All the antipsychotics are used for nonselective tranquilization and diminishing behavioral arousal. Acepromazine is commonly used for infrequent anxietal episodes, but it may induce a paradoxical hyperactivity in some dogs and cats. In one report, a dog with aberrant behavior (tail chewing, growling, snapping, barking) was controlled with thioridazine at 1.1 mg/kg. |
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Mood-stabilizing drugs (lithium, carbamazepine, and valproic acid) are unrelated chemical compounds that are used in human medicine to treat bipolar disorder, impulsivity, emotional reactivity, and aggression. Carbamazepine and valproic acid are also antiepileptic. Carbamazepine has been used in cats (25 mg/cat, PO, bid) to decrease
fear-related aggression against people, but it may paradoxically increase aggression against conspecifics. Lithium is excreted unmetabolized via the urine. Serum concentration monitoring is necessary due to its narrow therapeutic index (recommended range: 0.8-1.2 mEq/L). Side effects include polyuria, polydipsia, memory problems, weight gain, and diarrhea. In one report, lithium (75 mg total dose, bid) was used to treat dominance-related aggression and psychotic
behavior (random air-snapping, pawing) in a Cocker Spaniel. |
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Antidepressants can be used to treat behavioral disorders, including obsessive-compulsive behaviors, stereotypies, aggression, and inappropriate elimination. These drugs are classified as tricyclic compounds (tertiary amines, secondary amines), selective serotonin-reuptake inhibitors, and atypical antidepressants. |
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tricyclic antidepressants have been commonly used in veterinary medicine. Case reports indicate that treatment success for behavioral disorders is highly variable among drugs within the same chemical class. The antihistaminic effect of these agents may be a useful adjunct in controlling pruritus due to atopy and food allergies. Side effects include vomiting, diarrhea, hyperexcitability, sedation, arrhythmias including tachycardia, orthostatic hypotension, mydriasis,
reduced lacrimation and salivation, urine retention, constipation, and weight gain. Widening of the QRS complex on an ECG has been used as an early indication of toxicity. Amitriptyline hydrochloride has been used in dogs at 1-2 mg/kg for separation anxiety, anxiety-related aggression, urination due to submission or excitement, and allergy-related pruritus, and in cats at 0.5-1 mg/kg for urine marking and hypervocalization. Imipramine hydrochloride has been used in dogs at 2.2-4.4 mg/kg, bid-tid, for urination due to submission or excitement. Clomipramine hydrochloride has been used in dogs at 1-3 mg/kg for reducing lick behavior for canine lick granuloma and for stereotypies such as circling and tail chasing, and in cats at 0.5 mg/kg. In some countries it is approved
for treatment of separation anxiety in dogs. Doxepine has been used in dogs at 3-5 mg/kg. |
| Selective serotonin-reuptake inhibitors, including fluoxetine, sertraline, and paroxetine, have been used for treating psychogenic alopecia, allergy-related pruritus, dominance-related aggression, fearful behaviors, obsessive-compulsive behaviors, and urine marking. Dosages for fluoxetine are 1 mg/kg, PO, sid for dogs, and 0.5-1.0 mg/kg, PO, sid for cats. |
