2.2 Behavior Modifying Drugs

Question 1

Explain the underying principle of behavior modification.

Answer 1

1. each animal has a unique personality that influences their perception of and reaction to events
2. if an animal is predisposed to recieve stimuli negatively, their baseline emotionality will decrease over time in response to certain life events
3. long term drugs can reduce the potential of life events to negavively influence baseline emotionality
4. short term drugs can be used to suppress the memory of a negative event which long term drugs could not control

it is NECESSARY to perform behavioral therapy (training) alongside drug use - do not let owner become dependent on the medication alone

Question 2

What are the three phases of behavior modifying drug therapy use?

Answer 2

(1) initiation (4-8wks):

• risk of adverse effects: may predispose to agression
• delay in onset of main effects (4-8 wks)
• wait these weeks to ensure the effects are long-term and not simply a hypersensitization to the medication in the induction period

(2) maintenance (6-8mths): treatment continued until

• end of period for which drug is licensed
• there is a period of normal behavior
• there is an indication that emotional component is less significant, and behavioral training alone will be sucessful

(3) drug withrdrawal: reduce drug per week (1 week per month of treatment)

• if relapse, return to most recent effective dose
• no information on data sheets, but side effects are well recorded in humans (e.g., discontinuation syndrome with SSRIs)
• potential relapse if drug withdrawal is sudden

Question 3

What is the threshold principle in behavioral drug use?

Answer 3

• there is a threshold of arousal for an action to occur (e.g., barking or showing aggression)
• an arousing event (like seeing another dog) may move an individual above their personal threshold
• drugs may prophylactically reduce the potential of breaching this threshold
• drugs may retroactively reduce the negative memories of a moment this threshold was breached

Question 4

What is disinhibition?

Answer 4

a potential adverse effect of using behavior modifying drugs, particularly benzodiazepines (but can occue with TCA, SRI, SSRI, and acepromazine)

• loss of self-control: dog is more likely to exhibit negative behavior

Question 5

What are the major drug classes of bahavior modifying drugs?

Answer 5

1. serotonergic
2. dopaminergic
3. GABA-ergic

Question 6

Give examples of serotonergic drugs.

Answer 6

• amitriptyline: SRI (SRI:NRI = 1:4)
• clomipramine: SRI (SRI:NRI = 5:1)
• fluoxetine: first SSRI (SRI:NRI = 15:1)
• sertraline: SSRI (SRI:NRI = 150:1)
• trazodone SARI

note: while NRI action may be more effective, it may also increase side effects due to strong noradrenergic effects

• for this reason amitripityline (a tricyclic antidepressant: TCA) is no longer used

Question 7

What is the main dopaminergic drug?

Answer 7

selegiline (selective MAOlb inhibitor)

Question 8

What ithe main GABA-ergic drug?

Answer 8

benzodiazepine

Question 9

Explain how SRIs work.

Answer 9

increase the porportion of serotonin receptors bound in the post synaptic cleff by blocking serotonin reuptake

over time the receptors are down regulated: a greater proportion may now be occupied at any one time even without medication (new steady state)

effect: reduce likelihood of breaching arousal threshold

Question 10

Explain how SARIs work.

Answer 10

serotonin antagonist and reuptake inhibitor (SARIs) appear to act in two ways:

• prevent the reuptake of serotonin
• antagonize certain “undesirable” serotonin receptors and redirect them other, more desirable receptors

the main example is trazodone

Question 11

What is selegiline?

Answer 11

a drug which that increases dopamine within the synaptic cleft by selectively inhibiting MAOb (enzyme that degrades dopamine)

• as with SSRIs, selegiline decreases anxiety and fearfulness (makes training easier, even in normal animals)
• minimal adverse effects
• do NOT mix with TCA/SRI/SSRI, or ACP

NOTE: also has very low levels of MAOa inhibition

• MAO drugs cannot be used in dogs and cats as they interact with the diet (e.g., tyramine) BUT selegiline is a such low levels it may be used without diet modification

Question 12

What are benzodiazepines?

Answer 12

• used to induce amnesia
• anterograde use: before / at beginning of event
• retrograde use: after event

Question 13

How to choose a drug?

Answer 13

Start indicated medication

• if no effect after 4-8 weeks: change medication
• if partial effect: add medication
• if good effect: continue medication

review every 60 days: slowly withdraw when appropriate