Unit 9A - Anticonvulsants, Behaviour & Euthanasia

Question 1

What are anticonvulsants used for?

Answer 1

seizure prevention
action: supress the spread of abnormal electrical impulses from seizure focus to other areas of the cebreal cortex
All CNS depressants

Question 2

What are the 3 classes of anticonvulsants?

Answer 2

1. maintenance anticonvulsants - tx idiopathic epilepsy
2. Adjuncts - add-ons; when more seizure control is required
3. Drugs for emerg use and status epilepticus - diazepam(controlled), injectable phenobarbital (controlled), propofol

Question 3

What is the goal of maintenance anticonvulsants?

Answer 3

decrease frequency of seizzure (does not eliminate)
dec length and severity of individual seizures
prevent having more than 1 per day

Question 4

What is phenobarbital?

Answer 4

barbituate class anti-convulsant
commonly used, “for life”
usually PO, controlled drug
can’t miss doses (given q12hr)
req therapeutic drug monitoring
adverse effects w/ acute use : acute sedation/ataxia, PU/PD, polyphagia
adverse effects w/ chronic use: hepatotoxicity, causes induction of cytochrome P450 - leads to inc metabolism of phenobarbital (and potentially other meds patient is on) may need to inc dose over time to achieve same effect

Question 5

What is phenobarbital blood testing?

Answer 5

measuring actual lvls of phenobarbital in the blood to ensure the lvls are within the therapeutic range. too low/high = ineffective/toxic range
1st testing done approx 2 wks after starting once steady state is reached ~ 5 t1/2
very long half life - 1.5-3.5d, so timing of testing compared to an individual dose not important

Question 6

What is potassium bromide?

Answer 6

compound chemical w/ no din (KBr)
maintenance control drug for epilepsy
can be used on own, or adjunct when PB into enough to control seizures
common in drogs, for life
can’t miss doses, give q12hr
lvls need to be checked periodically
cannot give with high salt diet - body will keep Cl- and excrete Br-

Question 7

What are the side effects of potassium bromide? What about blood testing for it?

Answer 7

sedation, PU/PD, polyphagia (or sometimes inappetence)
vry long half life ~24hrs, testing done after steady state reached. Timing relative to dose not important

Question 8

What are some less common anti-convulsants?

Answer 8

may be used in combo w/ PB and/or KBr or used on own in certain situations
not common used due to cost/availability
Levetiracetam (keppra)
zonisamine
gabapentin

Question 9

What are emergency anticonvulsant drugs?

Answer 9

treating seizures at ome
treating status epilepticus (seizure activity continuing for more than 5 min)
need to stop this quickly
after ~30 min, get severe damage to the brain
after ~60min usually results in death

Question 10

What is diazepam? what is it used for?

Answer 10

benzodiazepine class tranquilizer - works by increasing gaba (inhib neurotransmitter)
2 ways: emerg drug hom or emerg in-clinic

Question 11

How might diazepam be used as a emergency at home drug and a emerg in clinic drug?

Answer 11

1. emerg @ home: “to be used in even of a seizure, very severe, lasting >5m, in event of >1 seizure within a 24h period”
   owners administer rectally
   give 2doses 15min apart
2. emerg in-clinic: cri or repeated IV bolus

Question 12

How do we store drugs?

Answer 12

store in dark, never in plastic, never mix w/ other drugs - therefore owner should not have preloaded in a syringe
controlled drug

Question 13

How is injectable phenobarbital used as a emerg anticonvulsant?

Answer 13

oral tablets for maintenance
injectable given IV for emerg use in clinic

Question 14

How is propofol used as emerg anticonvulstans?

Answer 14

for refractory seizures/status epilepticus (if not responding to other drugs), can use injectable propofol to anesthetize patient
Initial IV bolus, followed by a CRI
will usually stop seizure activity and maintain under anesthetic until seizure activity passes (usually continue for 6-12h; max 48hr) considerable monitoring/care required

Question 15

What are 3 behaviour modifying drugs?

Answer 15

1. Antipsychotic drugs - basically tranquilizers
2. Antidepressant drugs - tricyclic antidepressants(TCAs), selective serotonin reuptake inhibitors (SSRIs) and monoamineoxidase inhibitors (MAOIs)
3. Anxiolytic drugs - dec anxiety or fear

Question 16

What are antisychotic drugs? WHat are some examples of it?

Answer 16

Blocks ALL behaviour, good and bad, therefore some of the anims good traits are lost too
Causes hypotension
Acepromazine - blocks dopamine and stim of dopamine receptors in brain related to emotion

Question 17

What are antipsychotic drugs not recommended for?

Answer 17

For tx of aggression, as this is an ‘instinctual behaviour” and the animal may actually compensate for feeling of sedation or loss of awareness by becoming more aggressive

Question 18

What are antidepressant drugs?

Answer 18

tricyclic antidepressants like clomipramine clomicalm, amitriptyline elavil
These drugs work by decreasing the reuptake of serotonin and norepinephrine from the synaptic cleft, allowing them to accumulate there and prolong their stimulatiory activity which modifies “mood”

Question 19

How do we use tricyclic antidepressants?

Answer 19

separation anxiety
inappropriate urination and spraying in cats
psychogenic licking in cats
excessive feather plucking in birds
aggressive in dogs
May take wks b4 drug prods its intended effect

Question 20

What are selective serotonic reuptake inhibitors?

Answer 20

derived from TCAs but are more selective for only blocking serotonin reuptake (and not norepinephrine) prolongs the effect of serotonin
Fluoxetine (prozac = reconsile = vet version)
Like the TCAs, will take several wks before seeing behaviour changes. Don’t stop meds abruptly

Question 21

How is fluoxetine used?

Answer 21

Lack of serotonin can increase aggressive. Fluoxetine prolongs this effect so can be useful for dog-people aggression, dog-dog aggression, anxiety, obsessive compulsive disorders

Question 22

What are monoamine oxidase inhibitors?

Answer 22

inhib the enzyme monoamine oxidase (breaks down serotonin, dopamine and norepinephrine)
Ex. selegiline (anipryl) - to tx pituitary dependant cushions and canine cognitive dysfunction = old dong senility

Question 23

What is trazodone HCL?

Answer 23

antidepressant drug
inc serotonic lvls in brain
used in dogs for anxiety disorders/fears (storm phobia, vet, fireworks, situational anxiety)
Rapid onset of action and can be used “as needed” basis
Recommended 1-2hrs prior to stressful event

Question 24

What are the s/e of trazodone HCL?

Answer 24

relatively safe, s/e uncommon
Includes: food seeking behaviour, sedation, nausea and diarrhea
serotonin syndrome - lvls too high in brain - very uncommon, only concern if taking other drugs that increase serotonin lvls

Question 25

What are anxiolytic drugs?

Answer 25

tranquilizers belonging to the benzodiazepine group
Ex. Diazepam - @ low doses, anim will be relaxed/less excitable
Interfere w/ pets ability to learn or be trained
drug tolerance can develop
drug misuse (owners taking for themselves)
not used in cats bc unpredictable drug induced hepatopathy

Question 26

What are some other behaviour drugs used?

Answer 26

Gapapentin - used to control neuropathic pain and/or seizures
also started to be used w/ inc frequency as anti-anxiety med in cat
^^ ELDU and research limited at this point

Question 27

What are some other behaviour modifiers? WHat are they?

Answer 27

Neutraceuticals: Thera-bites, contains L-theanine, colostrum calming complex, DHA and EPA, and valerian root extract
Zylkene (derived from milk protein casein) can be used in combo w/ trazodone or gabapentin prior to coming to the vet to dec stress with vet visits
used in horses for travel, box stall rest
for overall anxiety reduction, requires long term use

Question 28

What are some pheromones used in cats, dogs and equines?

Answer 28

Feliway - facial pheromone analogue (original) and mammary gland pheromone (multicat)
Adaptil - dogs - pheromone prod by mother dog to calm puppies
Confidence EQ - equine appeasing pheromone - equine maternal pheromone

Question 29

What might we include in diets for behaviour modification

Answer 29

Royal canin calm has B vitamins, casein and tryptophan for calming

Question 29

What are some commong euthanasial drugs?

Answer 29

pentobarbital - controlled drug, euth solutions may not be sterile or completely free of other contaminants therefore do not use as anesthetic

Question 30

How is pentobarbital administered?

Answer 30

Iv - preferred, place as IV catch (extravascular drug burns) faster onset thru stage 1 and 2
IP - larger dose, takes long tup (20m in cat)
IC - only humane if unconscious (or under GA)
standard protocol to color blue for recognition

Question 31

What is T-61?

Answer 31

for smooth euthanasia of dogs
Each ml of T-61 contains
200mg embutramide for strong narcotic action and concurrently paralysed the resp centre
50mg mebozonium iodide which prods a curariform paralytic action on striated skeletal and resp muscles and rapidly induces circulatory collapse
and 5mg tetracaine hydrochloride, in aqueous solution with dimethylformamide as preservative

Question 32

How does T-61 work?

Answer 32

paralyses resp muscles inducing circulatory collapse and suffocation. Takes longer than pento and acts centrally
Only considered human when used in combo w/ other drugs like pento and/or heavy sedation/anesthesia
Horses - can help dec viscosity of pentobarbital
not a controlled drug
IV only
labeled in dogs can is used in other species

Question 33

What is potassium chloride and magnesium sulfate do?

Answer 33

in event pento not available, both are commercially available or can be compounded
Only acceptable use in unconscious patient
IV only
can see inc muscle contractions/fasciculations after death which can be traumatic for owners