Behaviour Modifying Drugs - Overview

Although many drugs are used to treat behavioural conditions in animals, there are only three psychoactive drugs specifically licensed for use in companion animals to treat behavioural problems. These are:

• Clomipramine (EU and USA license for the treatment of separation related problems in dogs).
• Selegiline (EU License for the treatment of behavioural problems with an emotional underlying origin).
• Fluoxetine (EU and USA license for the treatment of separation anxiety in dogs, when used in combination with behavioural therapy. Subsequently withdrawn from European market).

No psychoactive drugs are licensed for use in cats. A range of other drugs are used to treat behavioural conditions, including beta-adrenoceptor antagonists, benzodiazepines, azapirones, anticonvulsants and triazolopyridines. Some of these drugs are licensed for use in a companion animal species for another condition, but many are not licensed for use in any companion animal species. Examples are listed in the table below, however, most uses listed are unapproved, care should therefore be taken with their use:

Class of Drug	Drugs	Uses	Side Effects
Tranquillisers	Acepromazine	Sedation/restraint (no specific indication in behavioural therapy)	Hypotension, CNS stimulation, contradictory responses, caution in boxers and greyhounds
Benzodiazepines	Alprazolam, Clonazepam, Clorazepate, Diazepam, Lorazepam, Oxazepam	Acute anxiety, panic, short-term management of noise phobias	Hepatic necrosis after oral dosing in cats (potentially fatal), sedation, ataxia, increased appetite, paradoxical excitation, amnesia
Tricyclic Antidepressants (TCAs)	Amitriptyline, Clomipramine	Anxiety, separation anxiety, canine and feline fear aggression, feline urine marking, feline compulsive grooming, stereotypy, some narcoleptic disorders	Sedation, gastrointestinal (GI) effects, dry mouth, increased thirst, urinary retention
Selective Serotonin Reuptake Inhibitors (SSRIs)	Fluoxetine, Fluvoxamine, Paroxetine, Sertraline	Aggression, canine separation anxiety, compulsive disorders, feline urine marking	Lethargy, inappetence, anorexia, GI effects
Beta Blockers	Propranolol	Situational anxiety, social anxiety, augmentation therapy for SRI/SSRIS drugs	Bradycardia, lethargy, hypotension, syncope
Azapirones	Busiprone	Anxiety, feline urine marking, interact aggression	Uncommon, not sedating
Triazolopyridines	Trazodone	Anxiety, phobia, separation anxiety, used primarily as an augmentation for other psychoactive drug therapies
Anticonvulsants	Carbamazepine, Gabapentin, Levetiracetam, Phenobarbital, Potassium bromide	Behavioural problems arising from focal seizures (e.g. aggression, tail chasing)	Lethargy, ataxia, polyuria, polydipsia, polyphagia
Glial Modulators	Propentofylline	Reduced activity in dogs (as an adjunct therapy for dogs with cognitive dysfunction syndrome)
Monoamine Oxidase Inhibitors (MAO-Is)	Selegiline	Canine and feline cognitive dysfunction syndrome, fear related problems, spraying, hyperactivity, compulsive/stereoptypical disorders, specific phobias	GI effects, restlessness or lethargy, anorexia

Synthetic hormone analogues like megestrol acetate (Ovarid), have little or no rational use in behavioural therapy for reasons of non-specificity, and adverse effects which make their use unjustifiable. Phenothiazines such as ACP have a very varied level of effect and duration of action and affect both normal and abnormal behaviours without significantly altering emotional state, which is an out of date approach to behavioural therapy.

Licensed drugs have established data about their efficacy, side effects, contraindications and toxicity, which makes expected outcomes more reliable. Their use is supported by one or more controlled studies.