Choosing a premed

Question 1

Duration

• ACP
• alpha 2 agonist

Answer 1

• 4 hours, sometimes longer

- 1-3 hours

Question 2

Reversibilty

• ACP
• alpha 2 agonist

Answer 2

• no

- yes; atipamezole

Question 3

Sedative effect

• ACP
• alpha 2 agonist

Answer 3

• generally mild, slightly unpredicatble

- dose dependent; may be marked

Question 4

Effect on BP

• ACP
• alpha 2 agonist

Answer 4

• decreases
• increases then stabalises: stimulates alpha2 receptos: causes vasoconstriction: very pale MM. This causes hypertension. Baroreceptors then kick in; stimulating vagus decreasing HR. (can’t act upon vascular tone) goes from hyper to normotensive

Question 5

Effect on HR

• ACP
• alpha 2 agonist

Answer 5

• variable; may increase or decrease

- decreases!

Question 6

Effect on ventilation

• ACP
• alpha 2 agonist

Answer 6

• minimal

- usually slows rate but blood gases are well maintained (: they have a lower RR but oxygenation is higher than normal)

Question 7

analgesia

• ACP
• alpha 2 agonist

Answer 7

• none

- moderate

Question 8

Bensodizipine pharmacological effects

Answer 8

• minimal effects on CV and respiratory systems

- paradoxical excitement in healthy animals but good in already ‘sick’ (depressed) patients

Question 9

Benzodiazepine options

Answer 9

diazepam – preferably IV only
midazolam – any route (water soluble)
- None licensed for vet

Question 10

Antimuscurinics (anticholinergics)

• use
• options (2), their onset and duration and liscensing

Answer 10

Treatment of vagally induced bradycardia only (very unpleasant side effects: dry mouth, dilated pupils.)

atropine

• fast-onset, short duration
• licensed in dogs and cats

glycopyrrolate (glycopyrronium)

• slow onset, long duration
• not licensed in animals

Question 11

Antimuscurinics side effects

Answer 11

tachycardia
mydriasis
‘dryness

Question 12

when would you use a partial alpha 2 agonist?

Answer 12

minor / relatively non-painful procedure

Question 13

when would you use a full opioid agonist (alpha 2)

Answer 13

moderate to severely painful procedure, or where you’re unsure (never wrong to give it)

Question 14

Why would you combine ACP and alpha 2 agonist?

Answer 14

• synergistic effects
• improved sedation with lower doses of each
• lesser cardiopulmonary depression

Question 15

2y/o healthy lab considerations?

Answer 15

• will get excited is a BZP

- As size of dog increases, size of CNS does not necessarily increase with it: give bigger dose but not double!

Question 16

8 m/o bull dog considerations?

Answer 16

• BOAS (brachycephalic obstructive airway syndrome): want as light as possible
• think about the fact that alpha 2 provides a deep sedation but will recover faster (so if choosing alpha 2 use a low dose)

Question 17

15 y/o collie cross considerations?

Answer 17

• potential organ impairment (heart, liver, kidneys)
• increased CNS drug sensitivity
• slower drug metabolism

Question 18

7 year old GSD with ruptured splenic mass. considerations?

Answer 18

• hypovolemic? give fluids first!
• ACP: NO animal is vasoconstricted to maintain BP and this will cause them to vasodilate
• Alpha2: will drop CO
• BZP best choice!

Question 19

8 year old CKCSp. considerations?

Answer 19

• consider what effect premedicants will have on underlying heart disease?
• Prone to mitral endocardiosis
• BZP probably not best
• Alpha2: cause vasocontriction and make sit harder for blood to pump into aorta which increases regurgitation fraction
• ACP: will vasodilate a bit which improves blood flow. Also antiarrhythmic
• Opioid: partial is adequate

Question 20

2 commonly used drug combinations in cats

Answer 20

midazolam 0.2mg/kg
ketamine 5-10mg/kg
mixed, given IM (stings!!)
provides effective sedation in cats

medetomidine at up to 80g/kg
butorphanol at 0.2mg/kg
ketamine at up to 5mg/kg
mixed, given IM (stings!!)
provides effective sedation (bordering on anaesthesia) in cats

Question 21

Ketamine

• use
• why is it less commonly used in dogs?

Answer 21

• Can be useful in combination with other drugs for sedation/premedication
• less use in dogs as more predisposed to CNS excitation than cats; more likely to seizure