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1)   Sevoflurane

a)      Classification

i)        Fluorinated hydrocarbon

ii)       Chemical isomer of isoflurane

b)      General Information

i)        A volatile liquid of low solubility that is minimally metabolized by the liver

(1)   Liver metabolism exceeds that of isoflurane

ii)       Its extremely low solubility provided for the quickest inductions, level adjustments, and recoveries of the currently used inhalant anesthetics

(1)   With the exception of patients experiencing extreme respiratory compromise sevoflurane is rarely of any advantage over isoflurane

iii)     MAC

(1)   Dog 2.1 to 2.4%

(2)   Cats 2.6%

c)      Advantages/Recommended use

i)        This anesthetic agent is suitable for use with most veterinary patients

ii)       As with isoflurane, sevoflurane does not sensitize the heart to epinephrine induced arrhythmia

iii)     Along with isoflurane, an inhalant anesthetic of choice for patients with:

(1)   Liver disease

(a)    More liver metabolism than isoflurane (~5%) but no trifluoroacetic acid metabolites are produced

(2)   Intracranial disease

(a)    Less effect on CSF pressure compared to Halothane

d)      Cautionary Information

i)        As with any inhalant anesthetic, cardiac and respiratory depression result as anesthetic concentrations are increased

(1)   Not all patients under sevoflurane will be able to maintain adequate blood pressures

(2)   Switching to an alternative maintenance agent may be necessary

ii)       Compound A (resulting from sevoflurane/sodasorb interaction) appears to be of little concern

iii)     Although sevoflurane is considered a relatively safe agent as pertains to staff exposure, we should all strive to minimize our exposure to this or any other inhalant agent

e)      Dosage Information

i)        Routine use

(1)   Mask Induction

(a)    Start with 100% oxygen @ 3 liters/min for 3 - 5 minutes

(i)      Do not cover patients eyes

(b)   After 3 - 5 minutes of O2, start sevoflurane at 1 %

(c)    Increase by 1 % every 30 - 60 seconds until 3 % is reached

(d)   Then increase to 5 % - 7 % to complete induction

(2)   Induction following injectable agent

(a)    Initiate flow rates of 1.0 to 1 liter per minute at 3.5 % - 5.0 %

(i)      Reduce percentage as indicated by patients response

(3)   Maintenance

(a)    Once stable, reduce oxygen flow to 500 ml to 1 liter

(i)      The reservoir bag must remain full

1.      If not, the flow rate must be increased and the machine must be examined for leaks at the earliest possible convenience

(b)   Remember that prior to surgical stimulation, a patient may appear adequately anesthetized only to show a dramatic response to stimulation

(i)      An experienced anesthetist should be able to anticipate and minimize this event

(c)    Effective analgesic & sedative premeds will significantly reduce the level of inhalant agent necessary for maintenance of a surgical plane of anesthesia

f)       Cost

i)        high






a)      Classification

i)        50/50 mixture of a benzodiazepine (Zolazepam) & a dissociative agent (Tiletamine)

b)      General Information

i)        Similar to Ketamine and Diazepam

ii)       Can be used for induction in dogs and cats or as the exclusive agent for short procedures in cats

iii)     Tiletamine is capable of providing the loading dose for NMDA dorsal horn windup antagonism prior to ketamine CRI use

c)      Advantages/Recommended use

i)        Healthy animals in the Good to Excellent category

(1)   More ideal for cats vs. dogs

(2)   An acceptable induction agent for sighthounds

d)      Cautionary Information

i)        Avoid if:

(1)   Intracranial disease is suspected (can raise ICP)

(2)   Renal insufficiency is present (renal clearance)

ii)       Somewhat more stormy recoveries in dogs compared to Ketamine/Diazepam

(1)   The life of zolazepam is much longer than the life of the tiletamine in cats

(2)   The life of zolazepam is shorter than the life of the tiletamine in dogs increasing the risk that the patients will be more agitated during the recovery

(a)    This is less of an issue if a longer procedure over 1.5 hours

e)      Dosage

i)        Routine induction

(1)   Dog & Cat 2 mg/kg (1 mg/lb) IV bolus

(a)    Sedated or pre-existing CNS depression or debilitation - draw up 2 mg/kg (1 mg/lb), give 25 - 50% as bolus then additional increments to effect

ii)       Vicious, aggressive dogs

(1)   5 mg/kg (2.5 mg/lb) IM - usually reach lateral recumbancy within 10 minutes

(2)   May be combined with acepromazine for more dramatic effect

iii)     Routes of administration

(1)   IV allows for lower telazol doses

(2)   IM more rapid in effect but more painful

(3)   SC - somewhat less painful and somewhat lower effect but SQ administration is still a rapidly acting route

f)       Cost

i)        Moderately low



a)      Classification

i)        Ultra-short acting thiobarbiturate

b)      General Information

i)        Various concentration (2.5% and 5% solutions are the most common)

c)      Advantages/Recommended use

i)        Healthy animals in the Good to Excellent category

d)      Cautionary Information

i)        It is safer to consistently use the same concentration solution within a given facility rather than stocking both 2.5% and 5% solutions

ii)       Not recommended for use with sight hounds

(1)   Lower volume of distribution and altered metabolism make for a very narrow therapeutic index

iii)     Can cause significant decrease in PCV

(1)   Thiopental (and Acepromazine) cause splenic pooling of RBCs leading to a rapid decrease in PCV of up to 30%

iv)     Can induce myocardial irritability

(1)   Usually bigeminal

(2)   Treatment not required if stable cardiac output

v)      There is an accumulative effect with this agent

vi)     Extravascular thiopental may produce tissue necrosis

(1)   Infiltrate area with saline, 0.5 to 1 mg of dexamethasone and 1 mg/kg (0.5 mg/lb) of lidocaine

(2)   Additionally, a gauze soaked in DMSO can be wrapped over the site

vii)   Unused thiopental should be discarded whenever any precipitate is noted in solution or when 4 weeks has transpired since mixing even if no precipitate is noted

e)      Dosage Information

i)        Dog & Cat

(1)   Begin with 12 mg/kg (6 mg/lb)

(a)    Administer 4 to 6 mg/kg (2 - 3 mg/lb) rapid bolus initially followed by additional small boluses to effect

(i)      Excessively slow injection may precipitate unwanted excitement

(b)   Reduce initial bolus in proportion to degree of sedation produced by premeds

(2)   Maximum dose is 16 mg/kg (8 mg/lb)

(3)   If at any point the canine patient is nearly, but not quite, able to be intubated, the addition of 2 mg/kg (1 mg/lb) lidocaine IV, may deepen the anesthetic effect and facilitate successful intubation

(a)    This strategy is useful when minimizing the induction agent for more critical patients

(b)   Cats are more sensitive to the toxic effects of lidocaine (CNS stimulation, seizures). Lidocaine is not recommended for use in cats at this time.

f)       Cost

i)        Moderate



a)      Classification

i)        A dissociative agent

b)      General Information

i)        Combined with zolazepam to produce Telazol

ii)       For more information see Telazol


a)      Classification

i)        An analgesic medication with a dual mode of action

(1)   Mu opioid receptor agonist

(2)   Monoamine reuptake inhibitor

b)      General Information

i)         An uncontrolled, oral analgesic for use in dogs and cats

c)      Advantages/Recommended use

i)       Acute or chronic mild to moderate pain management

ii)       May be combined with other classes of analgesics including NSAIDs, NMDA antagonists, and gabapentin

d)      Cautionary Information

i)        May decrease seizure threshold

ii)       Do not combine with TCAs, SSRIs, or MAO inhibitors due to the risk of serotonin syndrome

iii)   Metabolism is principally via hepatic biotransformation, with a small amount excreted unchanged by the kidneys. Reduce dose or discontinue if significant hepatic or renal dysfunction exists

iv)  Side effects, though rare, may include GI upset and sedation

v)   This is a bitter medication that is not well accepted by cats even when compounded in a cat friendly liquid base. 

e)      Dosage Information

i)        Dog

(1)    3 to 5 mg/kg (0.5 to 2.5 mg/lb) TID to QID1

(b)   Anecdotal reports include 10 mg/kg QID for more severe pain

iii)      Cats

(1)    1 to 2 mg/kg (0.5 to 1.0 mg/lb) BID to QID

ii)       Tramadol is available in 50 mg tablets

f)       Cost

i)        Moderately low

    1 Pharmacokinetics of tramadol and the metabolite O-desmethyltramadol in dogs. KuKanich B, Papich MG. J Vet Pharmacol Ther. 2004 Aug;27(4):239-46

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Last modified: Friday February 06, 2009.