Anesthesia is defined as a pharmacologically induced reversible state of amnesia, analgesia, loss of responsiveness, and loss of skeletal muscle reflexes, or more simply
“without sensation”. In contrast, sedation is a “drug induced depression of consciousness during which patients cannot be easily aroused, but responds purposefully following repeated or painful stimulation.” (ASA) For the veterinary patient, the anesthetized animal achieves a surgical plane of anesthesia, while the sedated patient does not. Degree of sedation is variable.
The advantages of sedation primarily focus on patient safety. The comparative safety of sedation over general anesthesia in human patients is well established. A recent study comparing death rates in dogs, cats and rabbits indicated a 2.5 X higher death rate in anesthetized vs. sedated patients (Brodbelt). It is extremely likely that sedation can be associated with decreased risk in other species as well; therefore, sedation should be considered in place of general anesthesia whenever possible. Focus on the use of sedation in exotic animals is a direct result of the perception of greater anesthetic risk in these patients, especially in those that are ill or debilitated.
Other advantages of sedation include general reduction of anxiety and stress related to disease processes such as respiratory disease, and for diagnostic sampling and therapeutics. For some ill or extremely stressed patients, the risk of handling is moderate to unacceptably high. In many cases, the risk of handling must be weighed against the risk of foregoing diagnostic testing or procedures, or risk of general anesthesia. For these patients, sedation provides an attractive alternative.
Disadvantages of sedation can include incomplete elimination of patient movement, patient semi-awareness, and lack of complete analgesia. Drugs and lower dosages used for sedation are linked with greater patient safety, but are not entirely without risk.
Disadvantages can be overcome with careful dosing and monitoring, effective patient handling and efficient use of analgesics when handing or procedures are expected to produce discomfort.
The American College of Veterinary Anesthetists (ACVA) has published recommendations for monitoring patients that are sedated without general anesthesia
(ACVA recommendations). If the patient is sedated to the point where protective airway reflexes are lost, monitoring should proceed as with a fully anesthetized patient. In general, the goal of monitoring is to “…ensure adequate oxygenation and hemodynamic stability of the obtunded patient.” Monitoring is intermittent, and includes the following:
1. Palpation of pulse rate, rhythm and quality
2. Observation of mucous membrane color and CRT
3. Observation of respiratory rate and pattern
4. Auscultation
5. Pulse oximetry
Supplemental oxygen, and endotracheal tube (where applicable) and materials to obtain vascular access should be readily available.

Agents for Sedation in Mammals
Midazolam (Baxter Healthcare Corp, Deerfield, IL, USA) is commonly used in human and traditional pet medicine for purposes of pre-anesthesia and sedation. It has a wide margin of safety in many species. When combined with an opioid, effects are synergistic, allowing a reduction of the amount of either drug. Dosages most commonly used are
0.25-0.50 mg/kg, combined with an opioid (butorphanol, buprenorphine, hydromorphone, other). Effects in exotic species are promising, and the authors have not observed adverse effects in any species in which it has been utilized (avian, exotic mammals including rabbits, ferrets, rodents, primates, carnivores, and others). Effects are variable, from slight decrease in activity to lateral recumbency. Effects appear to be more pronounced in the ferret and in compromised patients, and less pronounced in rats and mice unless higher dose rates are used. These effects are likely related to species variability in response and the varying dose rates suggested for different species/groups.
In all cases, patients still react somewhat to handling and noxious stimuli.
When midazolam is combined with an opioid, greater sedation and analgesia result. It should be kept in mind that use of sedation and manual restraint alone is inappropriate for any procedure expected to produce discomfort. An exception may be in a calm patient with judicious and efficient use of local anesthesia in the form of a local or regional block (see below).
In mammals additional sedation can be provided with sub-anesthetic dosages of ketamine (Ketaset, Fort Dodge Animal Health, Fort Dodge, IA, USA) 5-10 mg/kg. If additional immobilization is essential, low concentrations of inhalant gas can be considered. This combination of drugs for sedation allows overall reduction of required inhalant gases, decreasing risk associated with the use of general anesthesia.
Agents for Sedation in Birds
The author used a combination of midazolam and butorphanol for use in birds. There is very little published information on the use of midazolam in psittacine species. Abou-
Madi described the use of midazolam combined with butorphanol for premedication of birds in 2001.
A single study described use for control of seizures in an orange winged
Amazon parrot with an ingested lead foreign body. A number of studies describe use of midazolam in combination with other drugs for anesthesia of guinea fowl and chickens.
Butorphanol is an opioid analgesic agent currently considered the most useful agent of its class in avian patients. Recent research has focused on pharmacokinetics, and has demonstrated safety in selected healthy psittacine species.
The author and others use butorphanol at 1-3 mg/kg, in combination with midazolam, at
0.25-1.0 mg/kg for sedation in avian patients. Pharmacologic data for use of midazolam alone or in combination with butorphanol in psittacine species is currently unavailable.
Agents for Sedation in Reptiles
The author overwhelmingly prefers the use of Alfaxalone for sedation of reptiles.
Alfaxalone (Alfaxan, Jurox, NSW, Australia) in an injectable anesthetic agent used for induction and maintenance of anesthesia in dogs and cats. The drug is available in
Australia, and the UK, but not currently manufactured and distributed in the United
States. Information of legal acquisition of Alfaxan for personal use in clinical practice in the United States is reported below.
The active molecule binds to GABBAA cell surface receptors. The plasma elimination half-life is approximately 25 minutes in dogs and 45 minutes in cats. Alfaxalone is completely cleared within a few hours after single intravenous dosing in these species, and is metabolized by the liver.
The drug can be used as a repeated bolus, or as a constant rate infusion (CRI) as part

of total intravenous anesthesia (TIVA). As a CRI, the drug does not accumulate and recovery does not appear prolonged. This is supported by the observation that repeated bolus doses in reptiles do not appear to prolong recovery.
Alfaxan is frequently used with pre-medications, including benzodiazepines and opiates.
It is described for slow intravenous use, with a recommended rate of administration of about 60 seconds. Alfaxan is labeled for intravenous use only. However the drug causes no irritation or untoward effects if administered extravascularly. The manufacturer does not recommend combining Alfaxan with other drugs into the same syringe.
Alfaxan appears to have a wide margin of safety. In a study in dogs, patients were administered a 10 times overdose and survived, but required respiratory support. Cats survived a similarly at a 5 times overdose.
Of significant benefit for the reptile practitioner, the drug appears to be highly effective when administered intramuscularly. There is no official manufacturer labeling or recommendations for IM use, or for use in species other than dogs and cats. However, the Australian Alfaxan website has a page suggesting anecdotally-derived dosages for use in a wide variety of exotic species, including birds, guinea pigs, rabbits, ferrets, kangaroos and a variety of reptile species. (It should be noted that some of the premedications suggested for use with Alfaxan are not commonly used in exotic pet practice.) In some species for which IV access is likely to be problematic, the site recommends IM administration. IM dosages in general tend to be higher than recommended IV dosages.
Off-label recommendations for reptiles are reported at 2-5 mg/kg IV, with a single recommendation for 10-20 mg/kg intra-celomically in the broad-shelled turtle.
The best uses for Alfaxan in reptiles appear to be the following: a) induction (with or without pre-anesthetics) followed by immediate intubation and maintenance with isoflurane; and b) sedation (with or without other agents) combined with local analgesia for brief, minor procedures. Even when combined with pre-medications, Alfaxan alone does not appear to achieve an acceptable surgical plane of anesthesia at currently explored dosages. Duration of action is variable but in general brief, often no more than
15 minutes. Full recovery is usually within one hour, but can be longer when combined with other agents, especially in debilitated patients.
Experience has revealed the following trends; however it should be kept in mind significantly higher case volumes are required to support the following conclusions:
Dosages ranges are 5-25 mg/kg. Ill or debilitated patients require significantly less drug than fractious, more stable patients. Dosages required appear to be higher in chelonians and green iguanas, and lower in snakes and leopard geckos. The author always begins with the lower end of the dosage range (5-10 mg/kg), adding boluses as needed to effect.
The author has experienced only one fatality directly related to administration of Alfaxan, in a moderately debilitated green tree frog with a rectal prolapse. The author also was unable to inject enough Alfaxan (before running out) to achieve anything close to sedation in a 25-pound sulcatta tortoise.
Local analgesia in Exotic Patients
Due to the small size of many exotic patients, dosages of local analgesics should be carefully calculated. Safe and effective dosages have not been established for many species, especially in birds and reptiles. Most studies in selected mammals have focused on drug distribution and not efficacy. A study in a rabbit demonstrated that dosages up to 9 mg/kg IV were generally tolerated.
The most commonly utilized agents for local block are lidocaine (Vedco, Inc. St. Joseph
MO) and bupivacaine (Hospira, Inc. Lake Forest, IL). Drugs are combined and diluted

with saline to desired volume. In studied species, The onset of action of lidocaine is rapid but short lived, while bupivacaine is slower to act but in some species may provide analgesia for up to 6-8 hours. The author has used both agents in mammals, birds and reptiles with apparent clinical success.
Notes on Importation of Foreign Drugs
Current US law permits importation of legal foreign drugs into the United States as long as the quantity does not exceed that representing a 30-day supply, and the drug is intended for personal use, e.g. within the veterinarian’s hospital, and not intended for redistribution. These rules are reflected in FDA’s Regulatory Procedures Manual,
Chapter 9-Import Operations and Actions, Section 9-2, Coverage of Personal
Importations, updated March 2009.
If a shipment is intercepted at the US border by FDA personnel, the recipient will likely receive a phone call requesting more information. Explain the shipment is a 30-day quantity of a legal foreign drug for personal use, and refer to section C of the personal drug importation guidelines as listed above. In nearly every case of which the author is aware, the shipment is released to the recipient. The worse consequence is return of the shipment to the country of origin. As long as the shipment does not contain an illegal or prohibited substance, there will be no legal action taken against the recipient.
To Order Alfaxan: Contact Jurox directly (www.jurox.com), or contact Vetafarm in
Australia: www.vetafarm.com.au
. This product is not listed on the company website, but can be requested via e-mail.