Small animal - induction agents

Question 1

what are the 4 induction agents used in SA?

Answer 1

1. propofol
2. ketamine
3. etomidate
4. alfaxalone

Question 2

What is the dose of propofol (IV)?

Answer 2

2-8 mg/kg

Question 3

What is the dose of ketamine (IV, IM)?

Answer 3

5-10 mg/kg

Question 4

What is the dose of etomidate (IV)?

Answer 4

0.5-1.5 mg/kg

Question 5

What is the dose of alfaxalone (IV, IM)?

Answer 5

2-5 mg/kg

Question 6

what is the MOA of alfaxalone?

Answer 6

• synthetic neuroactive steroid that acts on GABA receptors in the CNS
• producing typically sedative effects, and may also cause other effects such as anxiolytic, anticonvulsant, and muscle relaxant effects

Question 7

advantages of alfaxalone - 7

Answer 7

1. used for the induction and maintenance of anesthesia in both dogs and cats
2. administered slowly to effect it produces a rapid and smooth induction
3. good muscle relaxation
4. The duration of effect (6-12 minutes) is very similar to that of propofol
5. cardiorespiratory side effects (hypotension, vasodilation, hypoventilation) very similar to propofol
6. main advantage over propofol = flexibiliy of administration routes (IV, IM, SQ)
7. In cats, alfaxalone does not appear to accumulate to any appreciable extent when administered as a prolonged infusion, and recoveries are relatively short after prolonged alfaxalone administration (30-60 minutes for recovery)

Question 8

disadvantages of alfaxalone - 3

Answer 8

1. higher incidence of adverse events in recovery than propofol, with dogs exhibiting agitation and noise hypersensitivity
2. In cats, twitching is commonly reported in recovery, and both light and noise hypersensitivity are not uncommon as well, occasionally to the point of seizure-like activity
3. recover in DARK and QUIET place

Question 9

advantages of etomidate - 6

Answer 9

1. sedative/hypnotic induction agent
2. minimal CV effects
3. minimal respiratory effects
4. no histamine release
5. no dysrhythmias
6. wide margin of safety

Question 10

disadvantages of etomidate -

Answer 10

1. induction in unpremedicated animal may cause excitement, myoclonus, pain on injection, and apnea
2. high osmolality = administered in fluids to decrease pain and drug induced hemolysis
3. will cause adrenocortical suppression in dogs and cats for 2 to 6 hours = supplemental C steroids when used

Question 11

advantages of ketamine - 5

Answer 11

1. smooth and rapid induction
2. adjunct analgesic
3. IM to aggressive dogs and cats
4. appropriate for SIGHTHOUNDS
5. may increase sympathetic tone, which in turn generally increases cardiac output

Question 12

disadvantages of ketamine - 5

Answer 12

1. increases salivation
2. pain on IM injection
3. Vocalization, and delirium or seizure-like activity during recovery have been
   reported
4. muscle rigidity, occasional seizure activity = benzodiazepines should be administered in conjunction with ketamine in most patients
5. Although an indirect sympathomimetic, its direct effect at the myocardium is
   to cause depression.

Question 13

advantages of propofol - 4

Answer 13

1. ultra-short acting intravenous injectable anesthetic agent
2. smooth, rapid induction and recovery
3. unlikely to cause ventricular arrhythmias
4. good for SIGHTHOUNDS

Question 14

disadvantages of propofol - 4

Answer 14

1. dose dependent apnea and hypotension - minimize by slowly administering over 30-60 sec
2. Caution should be taken with the use of propofol in animals with a cardiac preload problem (eg blood loss or dehydration)
3. accumulates from CRI in cats
4. poor analgesic