1. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Fundamentals of Pharmacology for Veterinary Technicians Chapter 22 Behavior-Modifying Drugs

2. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Basic Terminology The use of drugs to treat problem behaviors is only a small part of treating animal behavior problems –Must correctly diagnose the condition, examine the social conditions, and alter external stimuli Potential side effects of long-term use –Liver, kidney, and cardiovascular problems Used extra-label –Must have veterinarian/client/patient relationship

3. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Classes of Behavior-Modifying Drugs –Anti-anxiety drugs Antihistamines Benzodiazepines Phenothiazines Azapirones Barbiturates –Antidepressants Tricyclics Monoamine oxidase inhibitors Selective serotonin reuptake inhibitors –Hormones Progestins Estrogen Testosterone inhibitors

4. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Anti-anxiety Drugs Anti-anxiety drugs attempt to decrease anxiety Types of anti-anxiety drugs –Antihistamines produce some degree of sedation because they suppress the CNS Used to treat anxiety associated with pruritus; the antipruritic effects of antihistamines appear to lessen this anxiety as well Examples include hydroxyzine and diphenhydramine

5. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Anti-anxiety Drugs Types of anti-anxiety drugs (cont.) –Benzodiazepines Are chemically related compounds used to relieve anxiety; appear to work on the limbic system of the brain by potentiating GABA Bind to specific sites in the brain; appear to produce sedation and relieve anxiety Used to treat aggression, urine spraying, and noise phobias Examples include diazepam, chlordiazepoxide, lorazepam, flumazenil, and alprazolam

6. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Anti-anxiety Drugs Types of anti-anxiety drugs (cont.) –Phenothiazines Are chemically related compounds that work by antagonism of dopamine (increased dopamine levels are associated with some psychotic diseases) Used to treat aggression (however, may make animals more reactive to noise) Examples include chlorpromazine, acepromazine, promazine, perphenazine, and prochlorperazine

7. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Anti-anxiety Drugs Types of anti-anxiety drugs (cont.) –Azapirones Chemically different from other anti-anxiety drugs; do not cause sedation Work by blocking serotonin; used to treat urine spraying and anxiety-associated aggression An example is buspirone –Barbiturates Have anti-anxiety action due to their ability to cause CNS depression (they have an effect on GABA) Used to control vocalization in cats and seizure-like anxiety in dogs Examples include phenobarbital and carbamazepine

8. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Antidepressant Drugs Antidepressant drugs are used to treat various mood changes (including aggression) and cognitive dysfunction in animals Transmission of nerve impulses between two nerves or between a nerve and tissue takes place via the release of neurotransmitters from storage sites at the nerve terminal After the neurotransmitter combines with the appropriate receptors, reduction of neurotransmitter concentration occurs –One mechanism involves the reuptake of neurotransmitter –Another mechanism involves destruction of neurotransmitter by monoamine oxidase (MAO)

9. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Antidepressant Drugs Tricyclic antidepressants (TCAs) –Work by interfering with the reuptake of serotonin by the presynaptic nerve cell; its metabolites inhibit the reuptake of norepinephrine –Increases the concentration of neurotransmitter at postsynaptic receptors in the CNS –Used to treat separation anxiety, pruritic conditions, and compulsive disorders in animals –Side effects include anticholinergic effects, liver problems, and thyroid effects –Examples include amitriptyline, imipramine, clomipramine, and doxepin

10. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Antidepressant Drugs Monoamine oxidase inhibitors (MAOIs) –Work by inhibiting the enzyme monoamine oxidase, thus reducing the destruction of dopamine, norepinephrine, and epinephrine –MAOIs irreversibly inhibit MAO –Used to treat cognitive dysfunction in dogs –Side effects include hypotension, drowsiness, and anticholinergic effects –An example approved for dogs is selegiline; extra-label examples include phenelzine, isocarboxazid, and tranylcypromine sulfate

11. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Antidepressant Drugs Selective serotonin reuptake inhibitors (SSRIs) –Work by inhibiting serotonin reuptake, resulting in increased serotonin neurotransmission –Used to treat depression, aggression, anxiety, phobias, and compulsive disorders –Side effects are few –Examples include fluoxetine, sertraline, and paroxetine

12. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Hormones Progestins and estrogens have calming effects due to their suppression of the excitatory effects of glutamine and their suppression of male-like behaviors Side effects include mammary gland hyperplasia, endometrial hyperplasia, bone marrow suppression, and endocrine disorders Examples include –Diethylstilbestrol: used for urinary incontinence –Medroxyprogestone acetate: used to treat male-like behaviors –Megestrol acetate: used to treat urine spraying, anxiety, aggression, and dermatitis conditions

13. © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation. Hormones Testosterone inhibitors inhibit the production of testosterone or block enzymes that convert testosterone to dihydrotestosterone (its potent form) Used to treat aggression in male dogs An example is delmadinone, which is used to treat aggression in male dogs The human product finasteride is used to treat benign prostatic hyperplasia and may be used in the future in veterinary medicine