Guidelines on Anesthesia and Analgesia in Hamsters
This document has been designed by the ULAM veterinary staff as a guideline for sedation, anesthesia, and analgesia of laboratory hamsters. This is not intended to be an inclusive tutorial on all possible drug combinations that can be used in hamsters. The following guidelines are also general recommendations and consequently do not include reference to specific research associated concerns.
All surgical procedures, anesthetics, analgesics, antibiotics or other medications used on animals must be approved by the IACUC, described in the animal use protocol and performed by personnel listed on the protocol and appropriately trained for the surgical procedure. Any techniques or drug protocols deviating from this document must be justified and approved in the IACUC protocol prior to application.
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Responsibility
- Principal Investigator: Responsible to ensure appropriate anesthesia and/or analgesia is provided for all hamsters undergoing painful procedures including rodent survival surgery unless otherwise indicated in the relevant approved protocol.
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Glossary Definitions
Anesthesia
This encompasses both of the following definitions:
- Local Anesthesia: Temporarily induces loss of sensation to a specific part of the body. May provide pain relief.
- Systemic Anesthesia: Temporarily induces loss of sensation with loss of consciousness. Only provides pain relief due to or during loss of consciousness.
Analgesia
Provides pain relief without loss of consciousness.
A/A
Anesthesia and analgesia.
Sedation
Central depression causing stupor where the animal is unaware of its surroundings but still responsive to painful procedures.
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Procedures
1. Prior to Anesthetic/Analgesic/Sedative Event
- Newly arrived animals should be acclimated at least 3 days prior to anesthesia or sedation. This allows them to adjust to any dehydration or anorexia that may have occurred during transport.
- Age and body weight should be considered when designing an A/A plan
- The high surface area to body mass of hamsters requires special consideration to prevent hypothermia (low body temperature) during and after anesthesia or sedation. Thermal support should be given while procedures are performed and while recovering. See Anesthesia and Sedation Monitoring Guidelines for more information regarding thermal support.
- Pre-anesthetic fasting is not necessary in rodents, and should not be done unless scientifically justified in the protocol. Water should NEVER be restricted.
- Cheek Flushing: Hamsters will store feed in their cheeks and this can lead to airway obstruction. To reduce the amount of material stored in the cheeks the mouth should be gently rinsed with tap water (10-20 ml) prior to induction. Also gently swab the inside of both cheek pouches with a cotton-tipped applicator to remove any remaining material.
- Apply sterile non-medicated ophthalmic ointment to the eyes to prevent corneal drying during anesthesia or sedation.
2. Routes of Administration
- More detailed information regarding injection techniques and maximum quantities safely administered to hamsters can be found in Guidelines on Administration of Substances to Laboratory Animals.
3. Normal Monitoring Parameters
- See Anesthesia and Sedation Monitoring Guidelines for more information on anesthetic/sedation monitoring requirements.
- Normal respiratory rate should be 35-120 breaths per minute
- A drop in respiratory rate of 50% can be normal during anesthesia.
- Respiratory pattern can be used to monitor anesthesia.
- Normal, regular versus abnormal, irregular breathing pattern
- Heart rate should be 250-600 beats per minute
- Normal temperature is 98.6 - 100.4°F (37 - 38°C)
- Mucous membrane color should be pink – never white or blue.
- Response to toe pinch, response to surgical stimulation, vocalization, blink reflex and corneal reflex can also be checked to assess anesthetic depth.
- Normal respiratory rate should be 35-120 breaths per minute
4. Recovery
- More information on monitoring parameters during post-operative recovery can be found in Guidelines on the Performance of Surgery in Rodents.
- Recover animals in clean cages without bedding to limit possibility of tracheal foreign body obstruction or pneumonia.
- Recover animals in the surgery area so they can be appropriately monitored during the recovery period.
- Supplemental heat should continue until the animal is sternal and ambulatory.
- If a large number of surgeries are being conducted at one time, animals may be housed together following anesthesia and prior to full recovery if they are continually observed (at least once every 2-3 minutes). This is to ensure that more alert animals do not cannibalize non-responsive cage mates.
- Nutritional support is critical following anesthesia and should be provided as soon as the animal is recovered.
- Moist chow, regular chow, or diet gel should be provided on the cage floor to encourage eating as soon as possible.
5. Dilution of Drugs
- Due to the small size of hamsters, drugs can be diluted for more accurate dosing. See Guidelines on the Preparation, Storage and Expiration of Injectable Medications document for more information.
6. Anesthetics
- Detailed information on all approved anesthetics and sedatives can be found in Anesthesia and Analgesia Drug Descriptions.
- Local anesthetics such as lidocaine and bupivacaine can be used to control pain at the incision site. Lidocaine and bupivacaine can be combined for a faster onset and longer analgesic duration. Ideally, local anesthetics should be administered before incisions are made.
- Table 1: Inhalant Anesthetics Used in Hamsters
Drug
Dose & Route
Comments
Isoflurane
Recommended4 - 5% for induction
1 - 3% for maintenanceRequires use of calibrated vaporizer
- Table 2: Injectable Anesthetics and Tranquilizers Used in Hamsters
a Subcutaneous (SC), Intraperitoneal (IP), Intravascular (IV)Drug
Dose and Route a
Duration
Comments
Dissociatives
Ketamine
+ Xylazine (Rompun®)
Recommended100 - 200 mg/kg ketamine IP
+ 5 mg/kg xylazine IP30 - 60 min
- To prolong anesthesia, supplement with 1/3 doses of ketamine only.
- Xylazine can be reversed with yohimbine or atipamezole.
Ketamine
+ Dexmedetomidine75 - 100 mg/kg ketamine IP
+ 0.25 mg/kg dexmedetomidine IP30 - 60 min
- Can partially reverse effects of dexmedetomidines with atipamazole.
Tiletamine-Zolazepam (Telazol®)
+ Xylazine30 mg/kg Telazol IP
+ 10 mg/kg xylazine IP30 min
Barbituates
Pentobarbital
50 - 90 mg/kg IP
30 - 60 min
- Poor analgesic effects.
- Dose sufficient to produce surgical anesthesia may cause severe respiratory depressions and death.
- High mortality rate with use; use with caution.
- Give diluted in saline (<10 mg/ml).
- AVOID buprenorphine co-administration.
- Buprenorphine and Pentobarbital will result in cardiorespiratory depression.
- Administer buprenorphine after full recovery.
Other
Alpha-Chloralose (1%, w/v)
Not Recommended, requires specific
justification in the protocol80 - 100 mg/kg IP
3 - 4 hours
- Do NOT use for survival surgical procedures.
Urethane (50%, w/v)
Not Recommended, requires specific
justification in the protocol1000 - 2000 mg/kg IP
6 - 8 hours
- Do NOT use for survival surgical procedures.
- Profound respiratory depression.
- Carcinogen/mutagen.
Reversal Agents
Yohimbine
0.5 - 1 mg/kg IP
- Reverses xylazine.
Atipamazole
1mg/kg SC, IP
- Reverses xylazine and dexmedetomidine.
- For dexmedetomidine reversal, the dose volume of atipamezole is the same as the preceding dose volume of dexmedetomidine.
Local Anesthetics
(see Procedures section 6.b above)Lidocaine
1 - 4 mg/kg topical, SC
30 - 60 min
- Analgesic. Onset in 5-10 minutes.
Bupivacaine
1 - 2 mg/kg topical, SC
3 - 4 hours
- Analgesic. Onset in 20-30 minutes.
Lidocaine
+ Bupivacaine1 - 4 mg/kg Lidocaine
+ 1 - 2 mg Bupivacaine topical, SC3 - 4 hours
- Analgesic. Combination of both drugs allows for rapid onset and prolonged effect.
7. Analgesics
- Signs of pain in hamsters may include, but are not limited to, the following:
- Abnormal posture
- Piloerection (raised fur)
- Reluctance to move
- Decreased activity
- Decreased appetite
- Weight loss
- Decreased tolerance to handling
- Decreased grooming
- Abnormal aggression
- Elevated respiratory rate
- Prevention and Management of Pain
- Limited information has been published on the use of analgesics for hamsters. Most of the dosages are extrapolated from data on other rodents or are empirical. Clinical assessment of pain response should therefore be used when selecting a dose.
- Table 3: Analgesics Used in Hamsters
a Subcutaneous (SC), Oral (PO)Drug
Dose & Route a
Frequency
NSAID b
Carprofen
5 mg/kg SC, PO
every 24 hours
Ketoprofen
5 mg/kg SC, PO
every 24 hours
Meloxicam
1 -2 mg/kg SC, PO
every 24 hours
Opioids
Buprenorphine c
0.1 - 0.5 mg/kg SC
every 8 - 12 hours
Oxymorphone
0.2 - 0.5 mg/kg SC
every 6 - 12 hours
b Nonsteroidal Anti-Inflammatory Drugs
c Preemptive analgesia, particularly opioids like buprenorphine, can reduce the dose of anesthetics required for surgical anesthesia and increase the respiratory depression associated with anesthetics. When preemptive analgesia is used, consider reducing the dose of anesthetic (whether inhalant or injectable) to the low end of the recommended range. Anesthetic depth must be carefully monitored and drug doses may need to be titrated to maintain appropriate levels. With new projects, sexes, strains or anesthetic analgesic combinations, assess a subset of animals before expanding to use in a larger cohort.
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References
- Carpenter JW. Exotic Animal Formulary, 4th edition. Elsevier Saunders 2013
- Flecknell P. Laboratory Animal Anesthesia, 3rd edition. Elsevier 2009.
- National Research Council (US) Committee on Recognition and Alleviation of Pain in Laboratory Animals. National Academies Press (US), 2009.
- Harkness, JE and Wagner JE. The Biology and Medicine of Rabbits and Rodents, 4th edition. Williams & Wilkins, 1995.
- Laboratory Animal Medicine, 2nd edition. Fox, JG et al. editors. Academic Press, 2002.
Questions?
If you have questions or comments about this document, contact ULAM Veterinary Staff ([email protected]).
The ULAM Training Core ([email protected] or 734-763-8039) can be contacted to provide training in techniques at no charge.
For any concerns regarding animal health after work hours or on holidays/weekends, contact DPS (3-1131) who will contact the on-call veterinarian.
