Canis ISSN: 2398-2942

Therapeutics: behavior modifiers

Contributor(s): Kyle Braund, Lauren Trepanier

Drugs to modify behavior

  • Relatively new field of treatment - wide range of drugs, many with other indications.
  • Must recognize limitations of medical treatment without behavioral modification programs Behavior: management Behavior: pharmacotherapy.


  • Antipsychotics → sedation, antimuscarinic effects, alpha-adrenergic blocking activity and extrapyramidal effects.
  • Sedation can limit efficacy of behavioral modification programs (by limiting ability to learn).
  • Acepromazine Acepromazine maleate.


  • Anxiolytic; minimal side-effects; serotonin agonists.
  • Buspirone hydrochloride* : for aggression, including fear related aggression but ineffective if exposed to intense stimuli; gradual onset of action.


  • Anxiolytics, low risk of toxicity; but long-term use → dependency, withdrawal anxiety (withdraw gradually) and interference with memory and learning.
  • Use mainly for short-term relief; very short half-life so needs frequent administration.
    Risk of disinhibition → paradoxical increase in aggression.
  • Clorazepate dipotassium*.
  • DiazepamDiazepam. Not useful for long term use in dogs: poor oral bioavailability, tolerance with time.
  • Alprazolam.


Tricyclic antidepressants

  • Prevent re-uptake ( → inactivation) of noradrenaline and 5-hydroxytryptamine.
  • Also have anxiolytic properties and useful in stereotypic conditions.
  • Non-selective re-uptake inhibitors:
  • Selective 5-HT uptake inhibitor:

Monoamine oxidase inhibitors

  • Not commonly used in veterinary practice - fatal toxic reactions with certain foods (due to inhibition of MAO-A present in gut, liver and sympathetic nerve endings).
  • Selegiline Selegiline: does not have above toxic effect; for 'canine cognitive dysfunction'. MAO-A inhibitor (irreversible) - selective for certain neurones and glial cells.

Beta-adrenoceptor blocking drugs

  • To reduce anxiety and decrease the somatic symptoms of anxiety - tremors and palpitations; may be useful in aggression.
  • PropranololPropranolol. Non-selective beta blocker.


Opioid antagonists

  • Stereotypic behavior, eg self-mutilation, tail-chasing, flank sucking and acral lick dermatitis.
  • Concern about effect on other aspects of behavior.
  • Naloxone hydrochlorideNaloxone : injectable only.
  • Naltrexone hydrochloride*.


  • For car travel and mild sedation to counter apprehension, ie using side-effects of the drugs.
  • Chlorpheniramine maleateChlorphenamine.
  • Diphenhydramine hydrochlorideDiphenhydramine.

Hormonal preparations

  • Anti-androgen therapy for aggression or where there is a sexual component to behavior - progestogens have anti-androgenic properties, and → non-specific CNS depression.
  • Modern psychoactive drugs have largely superseded progestogens.
  • Delmadinone acetate Delmadinone : chemical castration useful to predict effect of surgical castration on hypersexual behavior; but it also acts on limbic system, so surgical castration may not have same effect; may be disinhibition → increased aggression.
  • Medroxyprogesterone acetate Medroxyprogesterone.
  • Megestrol acetate Megestrol acetate.
  • StilboestrolDiethylstilbestrol : for aggression after spaying, beware side-effects, eg bone marrow toxicity.
  • *Indicates drug not licensed for this use in this species.
    None of these are used in US for behavior.

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Further Reading


Refereed papers

Other sources of information

  • Plumb D C (1999) Veterinary Drug Handbook. 3rd edn. Iowa State University Press, Ames Iowa.