ANESTHETIC DRUGS

By Britney Hughey

ACEPROMAZINE Indicated uses – Acepromazine is a

phenothiazine tranquilizer with no direct analgesic properties. It can be used alone, as a premedicant, but is more effective when used in combination with an opioid narcotic agent. The addition of an opioid reduces acepromazine dose, and therefore also reduces the likelihood of hypotension or sustained, excessive sedation that can occur. Use of acepromazine as a sole agent is not recommended.

ACEPROMAZINE How Supplied – Injectable or tablet.

Each mL contains 10 mg Acepromazine Maleate.

Dosage – The dosage should be individualized, depending upon the degree of tranqulization required. As a general rule, the dosage requirement in mg/lb of body weight decreases as the weight of the animal increases. Dogs: 0.25-0.5 mg/lb of body weight. Cats: 0.5-1 mg/lb of body weight.

Administration Routes - IM, IV, SQ.

ACEPROMAZINE When to Administer – 1 hour prior to surgery.

Allow 15 minutes for onset of action. Duration of Effect – Up to 3 hours from onset

of action, depending on the particular animal.

Effects on Fetus – Safe for use in pregnancy, but use caution and don’t use near full term.

Cardiac Effects – Any tranquilizer should be administered in smaller doses and with greater care to animals exhibiting cardiac disease. Hypotension can occur after rapid intravenous injection causing cardiovascular collapse. Also may cause bradycardia.

ACEPROMAZINE Respiratory Effects – None. Other Effects – Tranquilizers are potent

central nervous system depressants and they can cause marked sedation with suppression of the sympathetic nervous system. Tranquilizers can produce prolonged depression or motor restlessness when given in excessive amounts or when given to sensitive animals.

ACEPROMAZINE Drug Contraindications – Phenothiazines may

potentiate the toxicity of organophosphates and the activity of procaine hydrochloride. Therefore, do not use Acepromazine Maleate Injection to control tremors associated with organic phosphate poisoning. Do not use in conjunction with organophosphorous vermifuges or ectoparasiticides, including flea collars. Do not use with procaine hydrochloride. Epinephrine is contraindicated for treatment of acute hypotension produce by phenothiazine-derivative tranquilizers since further depression of blood pressure can occur. Also, animals may require lower dosages of general anesthetics following Acepromazine.

ACEPROMAZINE Disease Contraindications – Use caution

with administration to animals exhibiting cardiac disease. Acepromazine maleate, like other phenothiazine derivatives, is detoxified in the liver; therefore, it should be used with caution on animals with a previous history of liver dysfunction or leukopenia.

Reversal – Doxapram. Affects on the Pupil – None.

ATROPINE Indicated Uses – As a pre-anesthetic adjuvant

or to reduce salivation, bronchial secretion or internal peristalsis associated with colic or diarrhea.

How Supplied - Available in several concentrations.

Dosage – Available in several concentrations. Suggested dose for Atropine Sulfate: 1 mL for 20 lbs of body weight.

Administration Routes – IM, IV, SQ. When to Administer – 20-30 minutes before

anesthetic induction. Duration of Effect – 60-90 minutes.

ATROPINE Effects on Fetus – May cause fetal

tachycardia; safe if used with caution. Cardiac Effects – Bradycardia, reduced

cardiac output, heart rate increase. Respiratory Effects – Bronchodilation. Other Effects – Blocks stimulation of

vagus nerve, reduces salivation, reduces gastrointestinal activity, mydriasis, reduces tear secretions.

ATROPINE Drug Contraindications - The following drugs

may enhance the activity of atropine and its derivatives: antihistamines, procainamide, quinidine, meperidine, benzodiazepines, phenothiazines. The following drugs may potentiate the adverse effects of atropine and its derivatives: primidone, disopyramide, nitrates, long-term corticosteroid use (may increase intraocular pressure). Atropine and its derivatives may enhance the actions of nitrofurantoin, thiazide diuretics, sympathomimetics. Atropine and its derivatives may antagonize the actions of metoclopramide.

ATROPINE Disease Contraindications – Tachycardia

(heart rate over 140 bpm in dogs and over 180 bpm in cats), constipation or obstruction, shock, seizure disorders, head trauma, hypothermia, cesarean section, neonatal patients, cardiovascular or respiratory disease, debilitated animals, neonates and geriatrics, pregnant animals, large dogs prone to bloat, spinal cord or chest injury.

Reversal – Overdose can be treated with physostigmine..

Affects on the Pupil – Dilates pupils.

BUPRENORPHINE (BUPRENEX) Indicated Uses – Mixed agonist/antagonist

opioid of moderately long duration depending on dose. It has an agonistic effect at mu opioid receptor. Extremely high receptor affinity gives buprenorphine an antagonistic effect when mixed with pure mu opioids like hydromorphone, oxymorphone, morphine, or fentanyl which may be a strategic advantage. Dose has significant influence on duration of effect but no influence on degree of analgesia. Minimal sedation, limited reversibility, and moderate cost make this less attractive as a single agent premed.

BUPRENORPHINE How Supplied – Available as injectable

but usually prescribed as an oral spray or liquid.

Dosage – Dogs and cats 0.01 to 0.04 mg/kg; the dose influences the duration of effect but not the degree of analgesia.

Administration Routes – IM, IV, or can be absorbed through the veins under the tongue (sublingual).

BUPRENORPHINE When to Administer – For post-operative pain,

give after surgery. When given IV the onset is 15 minutes, when given IM the onset is 40 minutes.

Duration of Effect – One dose lasts approximately 6 hours in cats (depending on dose). Will last longer if given IM.

Effects on Fetus – Buprenorphine crosses the placental barrier, therefore it should not be given during pregnancy or nursing.

Cardiac Effects – Can cause a drop in heart rate as well as blood pressure.

Respiratory Effects - Respiratory depression is a possible side effect.

BUPRENORPHINE Other Effects – Excitement, hypersalivation,

excessive sedation, panting, sensitivity to sound, urinary retention, nausea, and vomiting.

Drug Contraindications – The sedation effect is more severe if this medication is used in conjunction with other medications that have a sedating side effect including antihistamines. Buprenorphine should not be used with selegiline or any other monoamine oxidase inhibitor. A 2-week waiting period is recommended if buprenorphine or any other narcotic is to be used in a patient on such a drug.

BUPRENORPHINE Disease Contraindications – Should not be

used in patients with respiratory compromise, including heart failure or head trauma. Buprenorphine is removed from the body via the liver, therefore patients with liver disease will have prolonged effects from this drug. Buprenorphine is contraindicated in patients with hypothyroidism, renal insufficiency, or Addison’s disease. Also contraindicated in geriatric or debilitated patients.

Reversal – Naloxone. Effect on the Pupil – Mydriasis (dilation).

BUTORPHANOL Indicated Uses – Mixed agonist/antagonist

opioid with short duration and very mild sedative effects. Agonistic effect at kappa and sigma opioid receptors. Antagonistic effect at the mu receptor which may be a strategic advantage. Reversibility is a subject of debate

How Supplied – Injectable and tablets; 2 mg base activity per mL.

Dosage – Dogs and cats 0.1 to 0.4 mg/kg. Increased dosages are NOT associated with an increase in analgesia.

BUTORPHANOL Administration Routes – IM, IV, or SQ. When to Administer – For IV, onset is 15 minutes. For

IM, onset is 40 minutes. Duration of Effect – 45 to 60 minutes in the dog; 60

to 90 minutes in the cat. Effects on Fetus – Safety has not been tested,

therefore use in pregnant animals is not recommended.

Cardiac Effects – Bradycardia, blood pressure decrease, decreased cardiac output.

Respiratory Effects – Respiratory depression (ceiling effect)

Other Effects – Excitement, hypersalivation, excessive sedation, panting, sensitivity to sound, urinary retention, nausea, and vomiting.

BUTORPHANOL Drug Contraindications – Should be used

with caution with other sedative analgesic drugs as these are likely to produce additive effects.

Disease Contraindications – None. Reversal – None. Effects on the Pupil – Mydriasis.

CARPROFEN (RIMADYL) Indicated Uses – Rimadyl is indicated for the

relief of pain and inflammation associated with osteoarthritis and for the control of postoperative pain associated with soft tissue and orthopedic surgeries in dogs.

How Supplied – Injectable or tablets. Available in 25, 75, or 100 mg tablets.

Dosage – The recommended dosage for oral administration to dogs is 2 mg/lb of body weight daily. The total daily dose may be administered as 2 mg/lb of body weight once daily or divided and administered as 1 mg/lb twice daily.

CARPROFEN Administration Routes – PO, SQ, IV, IM. When to Administer – Approximately 2 hours

before the painful procedure (or whenever the doctor advises).

Duration of Effect – This depends on the dose and form given.

Effects on Fetus – Safety has not been established.

Cardiac Effects – Not recommended in dogs with bleeding disorders (e.g. Von Willebrand’s disease). Potential for dysrhythmia.

Respiratory Effects – Potential for apnea.

CARPROFEN Other Effects – Vomiting, diarrhea/soft stool,

bilirubinuria, ketonuria, gastric ulceration, renal toxicity, hepatocellular toxicosis, renal hypoxia, acute renal failure.

Drug Contraindications – Do not use in patients under anesthesia.

Disease Contraindications – Don’t use in patients with GI disorders, congestive heart failure, hemostatic disorders such as thrombocytopenia, or in animals who are dehydrated. Do not use in patients receiving corticosteroids, animals with low blood pressure, or animals who have undergone trauma.

Reversal – IV fluids. Effects on the Pupil – None.

MEDETOMIDINE (DEXAMEDETOMIDINE, DOMITOR) Indicated Uses – Alpha-2 agonist;

medetomidine can be used alone, however it is often combined with an opioid for a synergistic effect. Addition of an opioid allows a reduction of the medetomidine dose and reduces the likelihood of the more dramatic negative cardiovascular effects that alpha-2 agonists can cause. Potent sedative and analgesic; substantially reduces induction agent need.

How Supplied – Injectable, 1 mg/mL. Dosage – Dogs and cats 0.002 to 0.04 mg/kg. Administration Routes – IV, IM.

DEXAMEDETOMIDINE When to Administer – Allow 20-30

minutes for drug to take full effect. Duration of Effect – NA. Effects on Fetus – This drug is not

recommended for dogs used for breeding purposes or pregnant dogs.

DEXAMEDETOMIDINE Cardiac Effects – Blood pressure is initially

increased due to peripheral vasoconstriction and thereafter drops to normal or slightly below normal levels. The initial vasopressor response is accompanied by a compensatory marked decrease in heart rate. A transient change in the conductivity of the cardiac muscle may occur, as evidenced by atrioventricular blocks. Cardiovascular changes (such as profound bradycardia and second degree heart block) equally affect both heartworm negative and asymptomatic heartworm positive dogs. There is a possibility for bradycardia, decreased cardiac output, and death from circulatory failure.

DEXAMEDETOMIDINE Respiratory Effects – Respiratory

responses include an initial slowing of respiration within a few seconds to 1-2 minutes after administration, increasing to normal within 120 minutes. An initial decrease in tidal volume is followed by an increase. There is a possibility of cyanosis, hypoxia, apnea, and severe congestion of the lungs.

Other Effects – Vomiting, depression. Drug Contraindications – None.

DEXAMEDETOMIDINE Disease Contraindications – Do not use

in animals with cardiovascular disease, respiratory disorders, liver or kidney diseases. Also should not be used in dogs with shock, dogs which are severely debilitated, or dogs which are stressed due to extreme heat, cold, or fatigue.

Reversal – Antisedan. Effect on the Pupil – None.

DIAZEPAM Indicated Uses – Sedation and

tranquilization of patients for easy handling; skeletal muscle relaxation, anticonvulsant, appetite stimulant, behavior modification.

How Supplied – Injectable. Also available in 2 mg, 5 mg, and 10 mg tablets.

Dosage – Use to effect. IM: 0.2-0.4 mg/kg; IV: 0.1-0.5 mg/kg in cats and dogs.

Administration Routes – IV, IM, SQ. When to Administer – Within 1 hour

before surgical procedures.

DIAZEPAM Duration of Effect – Depends on the route

given. Effects on Fetus – Diazepam should not be

used in early pregnancy as birth defects have been reported.

Cardiac Effects – Minimal. Respiratory Effects – Minimal. Other Effects – Some animals may get hyper-

excited on diazepam. In cats, cases of liver failure have been reported after several days use of diazepam. Liver issues do not seem to be a problem with use of brand name Valium. Also sometimes used as an appetite stimulant.

DIAZEPAM Drug Contraindications – May have a stronger than

expected effect if used in conjunction with cimetidine (Tagamet), erythromycin, ketoconazole, or propranolol. Antacids may slow the onset of effect of diazepam. The use of diazepam may increase the effect of digoxin. Diazepam should not be used in conjunction with amitraz (Mitaban) dips for mange, or in conjunction with ivermectin.

Disease Contraindications – Urine dipsticks that measure glucose may be falsely negative in patients taking diazepam. Some veterinarians avoid use after C-sections. Use caution in animals with known liver dysfunction.

Reversal – Flumazenil. Effect on the Pupil – None.

KETAMINE (KETASET) Indicated Uses – Ketaset may be used in

cats for restraint or as the sole anesthetic agent for diagnostic or minor, brief, surgical procedures that do not require skeletal muscle relaxation.

How Supplied – Injectable, 100 mg/mL Dosage – In cats, a dose of 11 mg/kg (5

mg/lb) is recommended to produce restraint. Dosages from 22-33 mg/kg (10-15 mg/lb) produce anesthesia that is suitable for diagnostic or minor surgical procedures that do not require skeletal muscle relaxation.

Administration Routes – IM, IV.

KETAMINE When to Administer – Onset is 90

seconds when given IV and 2-4 minutes when given IM.

Duration of Effect – 4-5 hours. Effects on Fetus – Has been shown to be

safe for use in pregnant animals. Cardiac Effects – Cardiac arrest is rare

but a possible side effect. Respiratory Effects – Respiratory

depression or dyspnea may occur following administration of high doses of ketaset.

KETAMINE Other Effects – Emesis, salivation, vocalization,

erratic recovery and prolonged recovery, spastic jerking movements, convulsions, muscular tremors, hypertonicity, opisthotonos, dyspnea and cardiac arrest. Death has been reported.

Drug Contraindications – None. Disease Contraindications – Ketaset is detoxified

by the liver and excreted by the kidneys; therefore, any pre-existent hepatic or renal pathology or impairment of function can be expected to result in prolonged anesthesia; related fatalities have been reported.

Reversal – Atipamezole. Effect on the Pupil – None.

MELOXICAM Indicated Uses – For the control of postoperative

pain and inflammation associated with orthopedic surgery, ovariohysterectomy and castration when administered prior to surgery in cats. In dogs, indicated for the control of pain and inflammation associated with osteoarthritis.

How Supplied – Injectable, 5 mg/mL. Also comes in an oral suspension.

Dosage – Dogs: 0.09 mg/lb (0.2 mg/kg) IV or SQ, followed 24 hours later by Metacam oral suspension at a daily dose of 0.045 mg/lb (0.1 mg/kg). Cats: 0.14 mg/lb (0.3 mg/kg) SQ. Use of additional meloxicam or other NSAIDs is contraindicated.

MELOXICAM Administration Routes – IV or SQ. When to Administer – 30-60 minutes

prior to painful procedure. Duration of Effect – 24 hours. Effects on Fetus – Safety in pregnant

animals has not been evaluated. Cardiac Effects – None. Respiratory Effects – None. Other Effects – Pain at injection site.

MELOXICAM Drug Contraindications – Do not give a

second dose of Meloxicam or follow with another NSAID.

Disease Contraindications – Meloxicam is not recommended for use in cats with bleeding disorders.

Reversal – None. Effect on the Pupil – None.

PROPOFOL Indicated Uses – A phenol in a hyperlipid

emulsion. Rapinovet is indicated for the following in dogs and cats: as a single injection to provide general anesthesia for short procedures, for induction and maintenance of general anesthesia using incremental doses to effect, or for induction of general anesthesia where maintenance is provided by inhalant anesthetics.

How Supplied – Injectable, 10 mg/mL. Dosage – Dogs 4 to 6 mg/kg. Cats 6 to 8

mg/kg. Administration Routes – IV.

PROPOFOL When to Administer – Immediately before

procedure. Duration of Effect – 2-5 minutes. Effects on Fetus – May be associated with

neonatal depression. Cardiac Effects – Bradycardia, hypotension,

cyanosis, tachycardia, and premature ventricular contractions.

Respiratory Effects – Panting, reverse sneezing, and cyanosis.

Other Effects – Paddling during recovery, tremors, movements, excitations, seizure, pain during injection, emesis, rubbing nose during recovery, or vocalization.

PROPOFOL Drug Contraindications – No significant

adverse interactions with commonly used drugs have been observed.

Disease Contraindications – Use cautiously in animals with cardiac or respiratory insufficiency.

Reversal – None. Effect on the Pupil – None.

TILETAMINE-ZOLAZEPAM (TELAZOL) Indicated Uses – Telazol is a 50/50

mixture of a benxodiazepine and a dissociative agent. Generally used in healthy animals in the good to excellent category.

How Supplied – Available in individual vials of 5 mL solution when reconstituted.

Dosage – Dogs and cats 2 mg/kg when unsedated. For vicious or aggressive dogs, 5 mg/kg.

TELAZOL Administration Routes – IM, IV, SC. When to Administer – Before surgical procedure. Duration of Effect – NA. Effects on Fetus – Teratogenic potential not

known; should not be used in pregnant animals. Cardiac Effects – Cyanosis, cardiac arrest,

pulmonary edema, tachycardia, and either hypertension or hypotension may occur.

Respiratory Effects – Respiratory depression may occur following high doses. May see transient apnea, excessive tracheal and bronchial secretions, cyanosis.

TELAZOL Other Effects – Emesis, excessive salivation,

vocalizations, erratic recovery and prolonged recovery, involuntary muscular twitching, hypertonicity, and muscle rigidity. Death has been reported in both dogs and cats.

Drug Contraindications – None. Disease Contraindications – Contraindicated in

patients with pancreatic disease, and preexistent renal pathology or impairment of renal function may be expected to result in prolonged duration of anesthesia. Telazol should not be used in dogs and cats with severe cardiac or pulmonary dysfunction.

Reversal – None. Effect on the Pupil – None.

XYLAZINE Indicated Uses – Should be used in dogs

and cats when it is desirable to produce a state of sedation accompanied by a shorter period of analgesia.

How Supplied – 20 mg/mL. Dosage – 0.5 mL/20 lbs. Administration Routes – IM, IV. When to Administer – Prior to surgery. Duration of Effect – 1-2 hours.

XYLAZINE Effects on Fetus – Don’t use in pregnant

animals. Cardiac Effects – Bradycardia with

partial A-V heart block. Respiratory Effects – Reduced

respiratory rate. Other Effects – Emesis, muscle tremors,

and increased urination in cats. Movement in response to sharp auditory stimuli may be observed.

XYLAZINE Drug Contraindications – None. Disease Contraindications – Not

recommended for use in patients with significantly depressed respirations, severe pathologic heart disease, advanced liver or kidney disease, severe endotoxic or traumatic shock and stress conditions such as extreme heat, cold, or fatigue.

Reversal – None. Effect on the Pupil – None.