Nov 12, 2013

References
1. Anaesthesia in the hamster using a combination of methohexitone and diazepam
John W Ferguson
Laboratory Animals (1979) 13, 305-308
Summary: The technique produces good anaesthesia with low mortality and may be used repeatedly,

2. Taber, R. & Irwin S. (1969). Anaesthesia in the mouse. Federation Proceedings, Federation of American Societies for Experimental Biology, 28, 1528-1532

3. Green, C.J (1975). Neutroleptanalgesic drug combinations in the anaesthetic management of small laboratory animals, Laboratory Animals, 9, 161-178

4. Green, C.J., Knight, J., Precious, S, & Simpkin, S. (1981). Ketamine alone and combined with diazepam or xylazine in laboratory animals, a 10-year experience. Laboratory Animals 15, 163-170.

5. Ketamine hydrochloride & xylazine hydrochloride anaesthestic in the golden hamster (Mesocricetus auratus). J L Curl & L L Peters, Laboratory Animals (1983) 17, 290-293
Summary: Several dose levels and routes of injection were evaluated. I.M., I.P. S.C. It was determined that 50-200 mg/kg bodyweight of ketamine with 10 mg/kg body weight of xylazine when given by intraperitoneal injection was a satisfactory general anaesthetic. This combination prove very useful in laboratory animal anaesthesia. They are administered premixed (23 gauge needle, 1-ml syringe) and have rapid induction and recovery times.

IM - posterior thigh muscles
IP right posterior abdominal quadrant
SC - dorsal thoracic subcutaneous tissues.

Plane of anaesthesia - based on response to painful stimuli & monitoring the loss of righting reflex. Painful stimuli --- pinching abdominal skin with haemostate -- body movement, muscle twitching and vocalisation --- not surgical plane of anaesthesia achieved. No analgesia.

Palpebral, corneal and pedal reflexes not used, inaccurate indicators of depth of anaesthesia.
No cardiovascular or respiratory evulation can be made

6. Hamsters, Biology, Care, Diseases & Models. Useful information on the Golden (Syrian) hamster and the Chinese hamster used in laboratory research in the US at:

http://netvet.wustl.edu/species/hamsters/hamstbio.txt

Anaesthesia/Chemical Restraint

              b.  Chemical restraint/preanesthesia/anesthesia

              AGENT                    DOSAGE

              Ketamine HCL             40-150mg/kg IM
                                       100-200mg/kg IP
              Xylazine(with ketamine)  10mg/kg IM Improves
                                       degree of relaxation

              Pentobarbital(10mg/ml)   50-90mg/kg IP
              Pentobarbital(60mg/ml)   90mg/kg  IP
                                       30mg/kg  IV

              Thiopental               20mg/kg  IV

              Morphine                 up to 150mg/kg IM;IP;SC
                                       analgesia w/o narcosis

              Inhalant anesthetics     cone;chamber;mask

              Atropine sulfate         0.2-0.5mg/kg SC

              c.  IV injection site:  saphenous vein


              d.  Common bleeding sites:

                  (1)  Cardiac puncture (requires anesthesia
                       2 ml/100gm animal safely)

                  (2)  Tail clip (no anesthesia,small quantities)

                  (3)  Orbital sinus (requires anesthesia,small
                       quantities)

              e.  Euthanasia

                  (1)  Physical methods

                        (a)  Cervical dislocation

                        (b)  Decapitation

                  (2)  Parenteral methods

                        (a)  Pentobarbital  135-150mg/kg IV
                             minimum

                        (b)  T-61 : not to be used when histo-
                             pathology is anticipated.

                  (3)  Inhalant methods

                        (a)  Carbon dioxide

                        (b)  Halothane

                        (c)  Methoxyflurane

                        (d)  Ether(explosive)


       E.  SPONTANEOUS DISEASES

          1.  Hamsters are generally very resistant to diseases
          and have few health care problems.  This, coupled with
          the fact that diseases can be readily induced, make the
          hamster ideal as a model for many human diseases.  Some
          disease conditions have been propagated by inbreeding
          to maintain specific models for human disease which are
          not common for the species as a whole.

          2.  Common diseases listed in descending order of
          occurrence (below)

              a.  Enteritis

              b.  Pneumonia

              c.  Neoplasia

              d.  Amyloidosis (old animals)

              e.  Polycystic disease

Many laboratory animals have been anaesthesized using injectable anaesthetics, most commonly pentobarbitone which causes significant mortality (Green, 1975). Pentobarbitone is long acting and produces respiratory depression. It is not possible to titrate depth and duration of anaesthesia (Taber & Irwin, 1969).

In Singapore in 2013, dwarf hamsters are most common as pets and much loved as family members by the younger generation. However, there is the misconception amongst many hamster owners that anaesthesia is fatal and so many owners delay surgical excision of skin tumours till they become gigantic. Some vets prefer not to ruin their reputation to anaesthesize such small animals to perform surgery to remove lumps and bumps resulting in deaths.

Many vets all over the world do not have the large number of cases to hone their skills and deepen their experience in anaesthesia. Hamsters are "cheap" pets costing $25. So many owners especially from the baby boomer generation will not want to pay $150 for anaesthesia and surgery, preferring to buy a new hamster.

Some vets will prescribe some oral medication. Some owners may buy off-the-counter creams to shrink the tumours, but they keep growing larger and larger.

USEFUL HAMSTER ANAESTHESIA should have the following criteria for minor surgery such as surgical exteriorisation of the cheek pouchs and excision of tumours.

1. Animal is unconscious (loss of righting reflex, rapid onset)
2. No signs of respiratory depression (marked cyanosis & shallow respiration).
3. No pain response to firm compression of a foot.

Zoletil 50 & isoflurane gas in healthy hamsters. Need to work fast. Hypothermia, blood loss controlled.

1. Minutes to onset of effect                 <1 br="">
2. Minutes to loss of righting reflex    1
3. Minutes to sedation 1-2 depending on dose and health
4. Minutes to peak effect 1-2
5. Minutes to loss of pain 1-2 (top up with isoflurane 5% mask, <3 p="" sec="">6. Duration of peak effect 1-2 minute (one or two top up with isoflurane).
7. Minutes to full recovery 1 min (if only isoflurane gas used). 5 minutes if healthy.

Haemorrhage in the muscles. So far, none observed as there is no complaints of limping or lameness post-op. No necropsy on muscles is done as in laboratory animal researchers as these are pet hamsters much loved by owners. Cremation is approved by owners if there are anaesthetic deaths or deaths post-operation due to ill health.

Anaesthetic deaths
1. poor health (thin, not eating, not pooping).
2. old age (>2 years).
3. blood loss
4. respiratory depression.
   ----------------------------------------------------------------

http://netvet.wustl.edu/species/HAMSTERS/HAMSTERS.TXT
Diseases in laboratory hamsters

http://netvet.wustl.edu/species/HAMSTERS/HAMFAQ.TXT
Newsgroup sharing info on hamsters

http://netvet.wustl.edu/species/HAMSTERS/PHODOPUS.TXT
Info on Russian dwarf hamsters

http://www.slideshare.net/SUNYUlsterInstructs/11-rodent-and-rabbit-anesthesia
useful slide show on rodent and rabbit anaesthesia
http://www.slideshare.net/SUNYUlsterInstructs/11-rodent-and-rabbit-aneshesia

7.

Case study : surgical approach to remove subcutaneous mass tumors in a campbell's dwarf hamster (phodopus campbelli)

Mokhamad Fakhrul Ulum, Sri Noviyanti Handayani, Yulia Riza, Ranti Asryyuni, Ekowati Handharyani

07/2010; In proceeding of: Proceedings of The 1st Congress of SEAVSA 2010
The Proceedings of the First Congress of South East Asia Veterinary St:hool Association IPS ICC, Bogar -Indonesia, July 20-22, 2010 CASE STUDY: SURGICAL APPROACH TO REMOVE SUBCUTANEOUS MASS TUMORS IN A . CAMPBELL'S DWARF HAMSTER (PHODOPUS CAMPBELL/) M.F. Ulum,(1l S.N. Handayani,(2l Y. Riza,(2l R. Asryyunl,(2l E. Handharyani

11. Rodent and Rabbit Anesthesia Presentation Transcript

1. Rodent and Rabbit Anesthesia Chapter 11
2. Patient Evaluation Difficult to obtain accurate information Shorter life spans Physical examination Transport to clinic Observe normal behavior and respiratory pattern before handling Safe and humane restraint
3. Handling and Restraint Mouse Pick up by base of the tail Rest on forearm for external examination Rest on rough surface for administration of injectables Injection sites
4. Handling and Restraint (Cont’d) Rat Nocturnal animals; awaken before handling Pick up around shoulders or lift by base of tail Rest on forearm, restrain by tail or around shoulders Injection sites
5. Mouse Restraint
6. Mouse Injections
7. Rat Restraint
8. Rat Injections
9. Handling and Restraint Hamster Temperament differences Nocturnal animal; awaken before handling Gentle and secure restraint Gerbil Very active; can easily escape Be careful of skin on tail Guinea Pig Immobile to agitated Swift and firm restraint
10. Hamster Restraint
11. Hamster Injection
12. Guinea Pig Restraint
13. Handling and Restraint Rabbits Breed variations Support back; animals kick with hind legs Lift by skin over shoulders; support abdomen Injection sites
14. Rabbit Restraint
15. Small Mammal Physical Examination Observe in transport box for undisturbed behavior Respiratory rate and pattern probably elevated Palpate or auscultate the heart rate
16. Small Mammal Physical Examination (Cont’d) Abnormalities Discharges from eyes and noses Labored/noisy respiration Soiled perineum Sunken eyes indicating dehydration Prominence of vertebrae and pelvis indicating poor body condition Rabbit: prolonged capillary refill time
17. Small Mammal Preanesthetic Diagnostic Tests Blood tests Rabbits Urinalysis Small rodents, rabbits, guinea pigs Radiography Small rodents, rabbits, guinea pigs
18. Preanesthetic Care Don’t withhold food and water Except when stomach is involved in surgery Must reestablish feeding as soon as possible after surgery Don't feed during the day Many animals are nocturnal Pain and discomfort can decrease appetite Correct preexisting problems Supportive fluid therapy for dehydration IV, SC, IP, or intraosseous routes
19. Preanesthesia Sedation is rarely needed prior to general anesthesia Protocols include a combination of injectable anesthetic agents or use of a chamber Rabbits may need prior sedation
20. Preanesthesia (Cont’d) Preanesthetics are used: Atropine Reduce salivation and bronchial secretions Don’t use in rabbits Opioid analgesics 30-40 minutes prior to induction Provides preemptive analgesia Sedatives or tranquilizers Given to rabbits prior to inhalation anesthesia
21. Preanesthetic Agents Anticholinergics Atropine and glycopyrrolate Phenothiazines Acepromazine Sedates but does not immobilize rodents Sedates rabbits and often provides enough immobilization for minor procedures Benzodiazepines Diazepam and midazolam Marked sedation in rodents and rabbits
22. Preanesthetic Agents (Cont’d) Alpha 2 -agonists Xylazine, medetomidine, and dexmedetomidine Sedation with some analgesia Higher dose may provide immobilization Side effects Same as in dogs and cats except vomiting Reverse with yohimbine or atipamezole (preferred)
23. Preanesthetic Agents (Cont’d) Opioids Provide preemptive analgesia Commonly used in combination with sedative agents Acepromazine and butorphanol helpful to get blood samples from rabbits
24. General Anesthesia: Induction Rabbits SC or IM routes most common IV may be possible Small mammals IP route less painful than IM route IP or IM vs. IV route of administration Cannot administer drug to effect One calculated dose is given High dose rates are required for proper depth Recovery times are prolonged
25. General Anesthetic Agents: Cyclohexamine Agents Ketamine Limited effect in small mammals when used alone Provides restraint in rabbits but not sufficient analgesia Ketamine/acepromazine and ketamine/diazepam or midazolam: produces surgical anesthesia in some rabbits and light anesthesia in small rodents Ketamine/alpha 2 -agonist (medetomidine or xylazine): provides analgesia and surgical anesthesia Variable results in guinea pigs Monitor anesthetic depth carefully
26. General Anesthetic Agents: Cyclohexamine Agents (Cont’d) Tiletamine Combined with zolazepam (Zoletil, Telazol) Light-to-medium anesthesia in small rodents Produces less analgesia than ketamine combinations
27. General Anesthetic Agents: Neuroleptanalgesics Neuroleptic (droperidol, fluanisone) combined with analgesic (fentanyl) Provides restraint and analgesia in small mammals Must combine with a benzodiazepine to produce surgical anesthesia Recovery enhanced by reversing fentanyl
28. General Anesthetic Agents Barbiturates in small mammals Narrow safety margin Severe cardiovascular and respiratory depression Prolonged recovery May be administered IV to rabbits Propofol Small rodents Not used because it must be administered IV Rabbits Short period of light anesthesia for ET intubation and gas anesthesia
29. General Anesthetic Agents (Cont’d) Alphaxalone Steroid anesthetic Induces anesthesia in rabbits Administered IV
30. Inhalation Anesthetics: Small Mammals Anesthetic chamber is the most convenient method to induce anesthesia Appropriate size Fill from bottom; excess gases removed from top Isoflurane, desflurane, and sevoflurane used in small rodents Rapid induction; rapid recovery Deliver with precision vaporizer into chamber Maintain with face mask Scavenge waste gas
31. Anesthetic Induction Chamber
32. Inhalation Anesthetics: Rabbits Rabbits often hold their breath when exposed to inhalation agents May lead to bradycardia Using face mask may lead to struggling Using chamber may result in violent attempts to escape Preanesthetic agents are preferred prior to induction Less struggling but may still hold breath Induce general anesthesia with face mask
33. Intubation of Rabbits and Small Rodents Rabbits Uncuffed ET tubes and laryngoscope with blade or canine otoscope Larynx is visualized or blind technique Small rodents Nasal catheter positioned in back of pharynx Does not allow for assisted ventilation Waste gases removed by extract tube close to nose
34. Nasal Catheter
35. Monitoring Anesthesia Out-of-circuit vaporizer Open, nonrebreathing system Fresh gas flow rates Depth of Anesthesia Small rodents Tail pinch and pedal withdrawal Rabbits and guinea pigs Ear pinch reflex
36. Anesthetic Delivery in a Rabbit
37. Monitoring Anesthesia Heart rate and rhythm Rabbits and guinea pigs Auscultate chest wall, palpate chest wall, esophageal stethoscope (rabbit) Small rodents Palpate chest wall Capillary refill time Rabbits only
38. Monitoring Anesthesia (Cont’d) Blood loss Small mammals have a small total blood volume Monitor blood loss carefully Arterial blood pressure Rabbits only Catheter in central ear artery, oscillometric technique, or Doppler probe
39. Blood Pressure Monitoring and Pulse Oximeter Probe
40. Monitoring Anesthesia Respiratory rate and depth Observe chest movements; no reservoir bag Normal rates during anesthesia Small rodents 50-100 bpm; rabbits 30-60 bpm 50% drop in bpm requires attention Pulse oximetry Need monitor with upper limit 350 bpm Place across hind foot in small rodents Place across a toe in large rabbits Tail, tongue, and ear can also be used
41. Pulse Oximeter Probe
42. Monitoring Anesthesia Capnography Side-stream vs. mainstream capnographs Thermoregulation Increased ratio of surface area to body weight Rapid cooling during anesthesia Monitor rectal temperature with electronic thermometer Shave a minimal surgical site Place animal on a warming pad Warm fluids prior to administration Continue warming during the recovery period
43. Postoperative Care Recovery area 95º F (35º C) while animal is unconscious 79º F-81º F (26º C-28º C) after animal is conscious Warm comfortable bedding (synthetic sheepskin) Encouraged to eat ASAP Provide water in familiar container SC or IP warmed fluids (98.6º F or 37º C) Postoperative analgesia
44. Anesthetic Emergencies Respiratory depression Determine cause Intubated Check ET tube placement; administer 100% oxygen Not intubated Extend head and neck and gently compress chest Small rodents Place soft rubber tubing or syringe barrel over nose and mouth and blow gently to inflate lungs Administer doxapram
45. Assisting Ventilation in a Rat
46. Anesthetic Emergencies Circulatory failure IV fluid therapy SC and IP routes provide minimum benefits Blood transfusion from donor animal Plasma volume expander Cardiac arrest External cardiac massage Emergency drugs at appropriate dose rate and volume
47. Postoperative Analgesia Pain assessment obstacles Nocturnal animals Fear or threat response to humans by going immobile Procedure for undisturbed animals Observe abnormal posture or hunched body Look for hair coat that is unkempt and ruffled with piloerection Rats: black discharge from eyes and nose Animal positioned at back of cage or buried in bedding
48. Postoperative Analgesia (Cont’d) Procedure for disturbed animals Encourage the animal to move and observe gait or posture and the presence of aggression Apathy or aggression when handled Vocalization (or no vocalization) and biting Immobility Monitor food and water intake by monitoring body weight
49. Analgesic Agents Opioids Shorter duration of action Buprenorphine preferred, 6-12 hours of action Other drugs may require repeated doses Combine with NSAID Nonsteroidal antiinflammatory drugs Carprofen, ketoprofen, meloxicam Prolonged duration of action, 12-24 hours Monitor long-term use for side effects
50. Analgesic Agents (Cont’d) Local anesthetics Infiltrated around surgical wounds or specific nerve blocks Narrow margin of safety; calculate dose carefully Shorter duration of action Topical agents used for venipuncture or IV catheter placement Chronic pain Arthritis, dental disease, neoplasia NSAIDs most successfully used; monitor long-term use
51. Administration of Analgesics IV administration Difficult in small rodents; straightforward in rabbits IM administration Rodents have small muscle masses SC Preferred route for rodents Oral May require firm physical restraint Can be added to highly palatable food if animal is eating
52. Analgesia and Postoperative Rules of Thumb Don’t recover small mammals in the same room as their predators Preemptive analgesia administration is usually more effective than postoperative administration Opioids administered prior to inhalation anesthesia can reduce the amount of inhalant anesthetic needed
53. Analgesia and Postoperative Rules of Thumb (Cont’d) Preemptive analgesia is more difficult when injectable anesthetics are used If opioids are being used as the analgesic with injectable anesthetics, the opioids should be administered at the end of the anesthetic period Not all NSAIDs can be used safely preoperatively because of their effects on the kidney and bleeding times

Monday, April 5, 2010

11. Hamster anaesthesia query from South Korea

E-MAIL TO DR SING DATED JAN 5, 2010

Hello Dr Sing Kong Yuen,

Happy new year!
I'm very impressed "be kind to pet" of your homepage and operating small animal clinic in South Korea.
I have poor experience about exotic pets and especially anesthesia of them.
May I(as begginer) ask favor of you about pre-eminent experience at exotic medicine?
I have pyometra patient in hedgehog and scalp laceration at font head in hamster.
Could you recommend anesthesia protocol(inhalant and injectable) each.
Hamster with amputated leg by cage had been experienced irratic and deep breath, and death in anesthetic chamber. Other hamster was not maintained enough to do surgery with ketamine 40-120mg/kg only.
How do you evaluate anesthesia depth and deal with problems.
I have general patient monitor for heart rate with alligator clips and pulse oximeter.
Could I use it in rodent?
Do you usually use absorbable suture at skin and why ?

I appreciate you in advance!
Be happy and wealthy!
Keep Healthy!

Sincerely yours,

Name of Vet

E-MAIL REPLY FROM DR SING DATED JAN 6, 2010

보낸 시간: 2010년 1월 6일 (수), 5:31:38 AM
제목: Re: Hamster and Hedgehog anesthesia in Korea

I am Dr Sing from Singapore, not from South Korea. My surgery is www.toapayohvets.com. I don't have hedgehog patient. The following applies to dwarf hamsters mainly. For Syrian hamsters, the same principles of close observation apply.

For sick dwarf hamsters needing surgery, I use isoflurane gas anaesthesia (plastic container) at 5% for around 1 minute, but close observation of the hamster is the key to success.

In other cases of healthy hamsters for tumour removal, I use Zoletil 50 as little as 0.01 ml IM as sedation. Then I use 5% isoflurane gas for less than 20 seconds and take out the hamster from the gas container to operate. If the hamster moves, I repeat the gas anaesthesia. Then I take it out to operate. Operation room must be warm to prevent hypothermia. If you have a cold operating room, you need to reduce the temperature or switch off the air conditioning during surgery. Hamster should be as dry as possible.

In this way, I maintain the surgical anaesthesia to operate. Most surgeries are less than 10 minutes. I have not used ketamine or other injectable anaesthesia except Zoletil on dwarf hamsters, so, I cannot share my experience with you.

Surgical anaesthesia levels are very difficult to assess in the dwarf hamster unlike in the dog and cat. Close observation of starting eyelid closure, movement and breathing rate is extremely important as there is a very high risk of anasthetic death if the vet does not know what he should observe or being too busy doing surgery.

You may need to have a very good veterinary assistant to help you observe the anaesthesia while you do surgery. But you should be able to know too when the hamster moves.

I don't know whether you can use pulse oximeter on dwarf hamsters. I use absorbable 6/0 or 7/0 sutures to stitch the hamster's skin so that owners don't need to come back for suture removal.

I hope this e-mail answers your questions.

E-MAIL TO DR SING DATED JAN 6, 2010
Subject: 답장: Hamster and Hedgehog anesthesia in Korea
To: "David Sing"

Dear Dr David Sing,

Thank you so much for your help!
How long can you maintain hamster with Zoletil 0.01ml im ?
At recovering anesthesia, how do hamsters act ?
At gas anesthesia, if depth of anesthesia is decreased and hamster could move, you put hamster in plastic container again.
Did you use continously anesthetic machine with nose cone described Saunder's manual of small animal practice?
What's there merit or demerit of continous or intermittent gas anesthesia.
Do you prefer intermittent gas anesthesia because of some reason or not ?
I considered aceromazine sedation, ketamie sedation, ketamine/xylazine anesthesia, zoletil anesthesia, and gas anesthesia
but I didn't successfully experience them.

I'd appreciate once more you in advance!

PS) I added photocopy of Saunder's manual of small animal praqctice and exotic animal formulary.

Best regards,

E-MAIL FROM DR SING DATED MAR 6, 2010

Thank you for your email. Now, I have time to reply to you. See below.

How long can you maintain hamster with Zoletil 0.01ml im ?
LESS THAN 2 MINUTES

At recovering anesthesia, how do hamsters act ?
SMOOTH QUIET RECOVERY AS IF THEY JUST WAKE UP

At gas anesthesia, if depth of anesthesia is decreased and hamster could move, you put hamster in plastic container again.
YES, I PUT INTO PLASTIC CONTAINER AND GIVE ISOFLURANE GAS FOR A FEW SECONDS.

Did you use continously anesthetic machine with nose cone described Saunder's manual of small animal practice?
NO

What's there merit or demerit of continous or intermittent gas anesthesia.
I THINK CONTINUOUS GAS ANAESTHESIA IS TOO RISKY FOR HAMSTER. DEPENDS ON YOUR DOSAGE.

Do you prefer intermittent gas anesthesia because of some reason or not ?
INTERMITTENT PREFERRED FOR ME. NEED CLOSE OBSERVATION OF HAMSTER'S STAGE OF ANAESTHESIA AND SHORT DURATION.

I considered aceromazine sedation, ketamie sedation, ketamine/xylazine anesthesia, zoletil anesthesia, and gas anesthesia
but I didn't successfully experience them.
DO YOU YOU USE ZOLETIL ANAESTHESIA?

I'd appreciate once more you in advance!

E-MAIL TO DR SING DATED MAR 6, 2010
Thanks you very very much !

P.S. Singapore government prohibits exotic pets. So, I don't get hedgehogs or reptiles. 99% of my hamster cases are dwarf hamsters nowadays!

INFO FROM SOUTH KOREA VET
Saunder's manual of small animal practice and exotic animal formulary
INJECTABLE ANAESTHETIC DRUGS FOR POCKET PETS

For hamsters
1. Acepromazine sedation 0.5 to 1.0mg/kg IM
2. Ketamine/xylazine anaesthesia 50-100mg/kg (ketamine) and 10mg/kg (xylazine) IP.
Wide dosage ranges are due to marked individual variations. Use lower dosages first.
3. Zoletil (tiletamine and zolazepam) anaesthesia 20-40mg/kg IM for chinchilla and rats. No mention about use in the hamster.
4. Zoletil/xylazine combination. 30mg/kg (Zoeltil) and 10mg/kg(xylazine) IM or IP
5. Isoflurane. Anaesthesia of choice for all pocket pets. 2.5% induction. 0.25% - 4% for maintenance.

I don't have experience using the above in my dwarf hamster anaesthesia and therefore am unable to comment except for isolfurane. All these formulae about 2.5% induction and maintenance are not much help. The vet has to go back to the fundamentals of the stages of anaesthesia and that is quite difficult for the hamster unlike the dog and cat. Be vigilant and be very careful even if you use isoflurane gas via mask. I don't do it.

ZOLETIL ANAESTHESIA FOR DWARF HAMSTERS AT TOA PAYOH VETS.
Over the last 5 years, around 100 dwarf hamsters had been operated using the following dosage of Zoletil 50.

For 4th year vet students, the details are as follows:

An adult dwarf hamster weighs around 40g.
Using the above, paragraph 3 --- Zoletil (tiletamine and zolazepam) anaesthesia 20-40mg/kg IM for chinchilla and rats. No mention about use in the hamster.

Let's calculate the dosage for the hamster weighing 40g.
The dosage should be (using lowest dosage of 20mg/kg) 20mg/1000g. This will be 0.8mg for 40g. Zoletil 50 is 50 mg/ml. Therefore, the volume of Zoletil 50 will be calculated as 0.01 ml at 0.5mg. For the 40g dwarf hamster, the volume should be a bit more than 0.01 ml at 0.015ml. However, 0.01ml was effective for less than 2 minutes of anaesthesia. For Syrian hamster, this volume was insufficient. I use 0.02 ml IM. In my practice, no anaesthetic deaths occur at this dosage. Isoflurane gas maintenance (intermittent) may be necessary when surgery exceeds 2 minutes.

Obviously the vet will not get any referral from hamster owners if he or she gets anaesthetic deaths frequently, unless the owner has no choices. Dwarf hamster anaesthesia is a particularly heart-breaking worrisome time but if the vet produces good clinical outcomes, it can be very satisfying to see the little creature alive with no more nasty tumours or wounds from bites. What the owner wants is a hamster alive from the vet. No excuses. Don't use a variety of drugs for hamster anaesthesia as you don't become competent. That is why I use Zoletil 50 or 100 only.

------------------------------------------

TOA PAYOH VETS
toapayohvets.com
Date: 17 May, 2011

Focus: Small animals - dogs, cats, hamsters, guinea pigs & rabbits

Hamster Anaesthesia At Toa Payoh Vets Dr Sing Kong Yuen, BVMS (Glasgow), MRCVSDate: 17 May, 2011

toapayohvets.com
Be Kind To Pets
Veterinary Education
Project 2010-0129

From: ...@yahoo.co.kr>
Subject: Hamster and Hedgehog anesthesia
To: judy@toapayohvets.com
Date: Tuesday, January 5, 2010, 7:16 AM

E-MAIL FROM A SOUTH KOREA VET TO DR SING

Hello Dr Sing Kong Yuen,

Happy new year!

I'm very impressed "be kind to pet" of your homepage and operating small animal clinic in South Korea. I have poor experience about exotic pets and especially anesthesia of them. May I (as beginner) ask favor of you about pre-eminent experience at exotic medicine?

I have pyometra patient in hedgehog and scalp laceration at font head in hamster.
Could you recommend anesthesia protocol (inhalant and injectable) each?

Hamster with amputated leg by cage had been experienced erratic and deep breath, and death in anesthetic chamber. Other hamster was not maintained enough to do surgery with ketamine 40-120mg/kg only.

How do you evaluate anesthesia depth and deal with problems.
I have general patient monitor for heart rate with alligator clips and pulse oximeter.
Could I use it in rodent? Do you usually use absorbable suture at skin and why ?

I appreciate you in advance! Be happy and wealthy!
Keep Healthy!

Sincerely yours,
Name

E-MAIL REPLY FROM DR SING
January 6, 2010

I am Dr Sing from Singapore, not from South Korea. My surgery is www.toapayohvets.com. I don't have hedgehog patient. The following applies to dwarf hamsters mainly. For Syrian hamsters, the same principles of close observation apply.

For sick dwarf hamsters needing surgery, I use isoflurane gas anaesthesia (plastic container) at 5% for around 1 minute, but close observation of the hamster is the key to success.

In other cases of healthy hamsters for tumour removal, I use Zoletil 50 as little as 0.01 ml IM as sedation. Then I use 5% isoflurane gas for less than 20 seconds and take out the hamster from the gas container to operate. If the hamster moves, I put the hamster into the gas container for less than 30-60 seconds. Then I take it out to operate.

1. The Operation Room must be warm to prevent hypothermia. If you have a cold operating room, you need to reduce the temperature or switch off the air conditioning during surgery.

2. The hamster should be kept as dry as possible. (No whole body washing with water as in a dog or cat after surgery. I use moist swabs to wipe away the blood on the body after surgery, as usually there is a lot of bleeding after tumour removal).

3. In topping up with isoflurane gas when the hamster moves, I maintain the surgical anaesthesia to operate. If the vet continues to operate while the hamster is struggling (i.e. not under surgical anaesthesia), the hamster may just die from shock. Always put the hamster under surgical anaesthesia whenever the hamster wakes up during surgery, to achieve a good outcome. Surgical anaesthesia levels are very difficult to assess in the dwarf hamster unlike in the dog and cat. Close observation of starting eyelid closure, movement and breathing rate are extremely important as there is a very high risk of anaesthetic death if the vet does not know what he should observe or is being too busy operating.

4. Most of my tumour surgeries are less than 10 minutes. Prepare your surgery in advance as time is of the essence.

5. I have not used ketamine or other injectable anaesthesia except Zoletil on dwarf hamsters, so, I cannot share my experience with you.

6. Avery good experienced veterinary assistant can help you to observe the stages of anaesthesia while you do surgery. But you should be able to know too when the hamster moves and stop the surgery promptly and put the hamster under isoflurane gas anaesthesia. I don't give further Zoletil injections to top up unlike in the case of the dog or cat as it will be fatal for the hamster.

7. I don't know whether you can use pulse oximeter on dwarf hamsters as it is such a small creature, unlike the dog or cat.

8. I use absorbable 6/0 or 7/0 sutures to stitch the hamster's skin so that owners don't need to come back for suture removal.

I hope this e-mail answers your questions.

E-MAIL TO DR SING DATED JAN 6, 2010
Subject: 답장: Hamster and Hedgehog anesthesia in Korea
To: "David Sing"

Dear Dr David Sing,

Thank you so much for your help!
How long can you maintain hamster with Zoletil 0.01ml IM ?
At recovering anesthesia, how do hamsters act ?
At gas anesthesia, if depth of anesthesia is decreased and hamster could move, you put hamster in plastic container again.
Did you use continuously anesthetic machine with nose cone described Saunder's manual of small animal practice?
What's there merit or demerit of continuous or intermittent gas anesthesia.
Do you prefer intermittent gas anesthesia because of some reason or not ?
I considered aceromazine sedation, ketamine sedation, ketamine/xylazine anesthesia, zoletil anesthesia, and gas anesthesia
but I didn't successfully experience them.

I'd appreciate once more you in advance!

PS) I added photocopy of Saunder's manual of small animal practice and exotic animal formulary.

Best regards,

E-MAIL FROM DR SING DATED MAR 6, 2010

Thank you for your email. Now, I have time to reply to you. See below.

How long can you maintain hamster with Zoletil 0.01ml IM ?
LESS THAN 2 MINUTES

At recovering anesthesia, how do hamsters act ?
SMOOTH QUIET RECOVERY AS IF THEY JUST WAKE UP

At gas anesthesia, if depth of anesthesia is decreased and hamster could move, you put hamster in plastic container again.
YES, I PUT INTO PLASTIC CONTAINER AND GIVE ISOFLURANE GAS FOR A FEW SECONDS.

Did you use continuously anesthetic machine with nose cone described Saunder's manual of small animal practice?
NO

What's there merit or demerit of continuous or intermittent gas anesthesia.
I THINK CONTINUOUS GAS ANAESTHESIA IS TOO RISKY FOR HAMSTER. DEPENDS ON YOUR DOSAGE.

Do you prefer intermittent gas anesthesia because of some reason or not ?
INTERMITTENT PREFERRED FOR ME. NEED CLOSE OBSERVATION OF HAMSTER'S STAGE OF ANAESTHESIA AND SHORT DURATION.

I considered aceromazine sedation, ketamine sedation, ketamine/xylazine anesthesia, zoletil anesthesia, and gas anesthesia
but I didn't successfully experience them.
DO YOU USE ZOLETIL ANAESTHESIA?

I'd appreciate once more you in advance!
Thanks you very much !P.S. The Singapore government prohibits exotic pets. So, I don't get hedgehogs or reptiles. 99% of my hamster cases are dwarf hamsters nowadays!INFO FROM SOUTH KOREA VET
Saunder's manual of small animal practice and exotic animal formulary
INJECTABLE ANAESTHETIC DRUGS FOR POCKET PETS

Generalised Ringworm. Syrian Hamster. Coat clipped very short. Treated at Toa Ppayoh Vets

For hamsters
1. Acepromazine sedation 0.5 to 1.0mg/kg IM
2. Ketamine/xylazine anaesthesia 50-100mg/kg (ketamine) and 10mg/kg (xylazine) IP.
Wide dosage ranges are due to marked individual variations. Use lower dosages first.
3. Zoletil (tiletamine and zolazepam) anaesthesia 20-40mg/kg IM for chinchilla and rats. No mention about use in the hamster.
4. Zoletil/xylazine combination. 30mg/kg (Zoletil) and 10mg/kg (xylazine) IM or IP
5. Isoflurane. Anaesthesia of choice for all pocket pets. 2.5% induction. 0.25% - 4% for maintenance.

I don't have experience using the above in my dwarf hamster anaesthesia and therefore am unable to comment except for isoflurane. All these formulae about 2.5% induction and maintenance are not much help. The vet has to go back to the fundamentals of the stages of anaesthesia and that is quite difficult for the hamster unlike the dog and cat. Be vigilant and be very careful even if you use isoflurane gas via mask. I don't do it.

ZOLETIL 50 ANAESTHESIA FOR DWARF HAMSTERS AT TOA PAYOH VETS.
Over the last 5 years, around 100 dwarf hamsters had been operated using the following dosage of Zoletil 50.

For 4th year vet students, the details are as follows:

An adult dwarf hamster weighs around 40g.
Using the above, paragraph 3 --- Zoletil (tiletamine and zolazepam) anaesthesia 20-40mg/kg IM for chinchilla and rats. No mention about use in the hamster.

let's calculate the dosage for the adult dwarf hamster weighing 40g.

The dosage should be (using lowest dosage of 20mg/kg) 20mg/1000g. This will be 0.8mg for 40g. Zoletil 50 is 50 mg/ml. Therefore, the volume of Zoletil 50 will be calculated as 0.01 ml at 0.5mg.

For the 40g dwarf hamster, the volume should be a bit more than 0.01 ml at 0.015ml. However, 0.01ml is effective for less than 2 minutes of surgical anaesthesia in my cases.

For Syrian hamster, this volume is insufficient as it weighs double or triple the weight of the dwarf hamster.

I use 0.02 ml IM. In my practice, no anaesthetic deaths occur at this dosage. Isoflurane gas maintenance (intermittent) may be necessary when surgery exceeds 2 minutes.

Obviously the vet will not get any referral from hamster owners if he or she gets anaesthetic deaths frequently, unless the owner has no choices.

Dwarf hamster anaesthesia is a particularly heart-breaking worrisome time but if the vet produces good clinical outcomes, it can be very satisfying to see the little creature alive with no more nasty tumours or wounds from bites.

Dwarf Hamster, 1.5 years. Cheek pouch tumour and abscess. Toa Payoh Vets

What the owner wants is a hamster alive from the vet. No excuses. Don't use a variety of drugs for hamster anaesthesia as you don't become competent. That is why I use Zoletil 50 or 100 only. Below is a case where Zoletil 100 is used. Do your dosage calculations well and you don't get hamster dying under anaesthesia!

ZOLETIL 100 IN A DWARF HAMSTER OPERATED IN MAY 2011The effective dosage of Zoletil 50, at 0.01 ml diluted with 0.03 ml Hartman in one syringe and given IM can be ineffective if the dwarf hamster is plump (over 60 g). I have isoflurane gas top up and therefore, it is not a problem. However, it is effective in slim dwarf hamsters of around 50 g bodyweight.

PLUMP HAMSTERS
Last week, I operated on a dwarf hamster, 57 g just using Zoletil 100 at 0.01 ml with 0.03 ml Hartman's solution in one syringe without the need for isoflurane gas top up. Surgery is faster if there is no need to top up. Do note that Zoletil 100 is double the strength of Zoletil 50 and if you use it in slim dwarf hamsters, you need to reduce the volume by half (that is, use one half of one drop from the tip of a 1-ml syringe).

This hamster went home to a happy lady owner 3 hours after surgery. Many hamster owners in Singapore wait till the tumour is large and irritating to the hamster before I see them. The anaesthetic risk is much higher. I don't look forward to operating on large tumours as there is a much higher chance of death on the operating table.

A younger generation of Singaporeans nowadays do get their hamsters with tumours operated unlike 10 years ago. However, many vets prefer not to operate on hamsters and prescribe cream or oral medication. Pet shops also recommend some cream but the medicine invariably does not work at all.

As around 50% of the 2 million voters in the Singapore General Elections 2011 are born after 1965, there is this young generation who is internet savvy and do lots of research.

Be kind to dwarf hamsters. Don't wait till tumour becomes large to ask your vet to excise it. Toa Payoh Vets

4150 - 4153. Zoletil 100 IM was sufficient to permit surgery in this 57-g dwarf hamster. Top up with isoflurane if necessary. I switched off the cold air-conditioning in the operation room and waited for a few minutes before operating on this hamster.

I don't bathe the hamster to remove all blood from the body as I would do in a dog or cat. I wiped off all blood stains with moist swabs myself rather than let the assistant do it. Then I kept the hamster in a cage after surgery in the room without air-conditioning and phoned the owner to take the hamster home 3 hours later. Sometimes, I do keep the hamster overnight to clean the wound.

3 days after surgery, the owner phoned me to say that the hamster was biting off her stitches and pulling off her home-made e-collar. What should she do?

Usually, I hospitalise the hamster for one day for observation after surgery. I had sent the hamster home 3 hours after the surgery as I did not think she would survive, due to the lots of bleeding after excision of the tumour. Therefore, it would be good for the young girl to spend some time with the hamster. On Day 3, the young girl phoned me as the hamster bit off one area under the armpit, showing some yellowish gap.

"Are you sure?" I asked.
"Yes, the whole area was fully stitched up. There were no holes."
I checked and said: "It is a small gap and should heal. I will give you the antibiotics and anti-inflammatory medicine."
The hamster squeaked every time she carried her and she said that this hamster had never squeaked before. "She is feeling the pain in the right armpit," I said. But this hamster did not bite.

I put the hamster on the receptionist counter which was a good height as the other clients were watching. Then I enveloped the hamster's body with a white towel so that she could not move and pushed 2 drops of medication into her mouth. The hamster would not open her mouth for the medicine and some pink syrup spilled outside her lower lips. "Take a tissue and wipe off the excess medicine," I showed the girl how to do it. Also, how to make an e-collar using a thicker paper and taping it.

As I write now, 2 days later, no news from her. I presumed all are well. Medication is usually given after tumour excision but this was not done. Not all hamster need medication post-operation. In any case, the hamster was eating. The problem was stitch biting as the area under the armpit was stitched quite tight. 6/0 stitches, simple interrupted at 3-mm intervals. The incision involved the armpit and so it was quite difficult for this active hamster to exercise. It was the location of the large tumour that extended to the below of the armpit. Early removal when it is small would be ideal.

It was a fine sunshine Sunday afternoon. So I asked the young lady to permit me to take some pictures of the hamster's armpit to illustrate the wound. She was happy to help me document this interesting case and held the hamster on top of a yellow iron pole outside the surgery.

Not much photographic success for me as you can see that I could not really get excellent zooming of the armpit with the few images I shot. I did not want to stress the owner or hamster and therefore took the pictures in less than 1 minute with a steady hand while she was supposed to rest her hand on top of the yellow pole to stabilise the images.

P.S. Time management on this busy Sunday was important. If I taught the girl how to medicate the hamster inside the consultation room which was occupied by my associate vet or in another room, I would waste several precious minutes by not attending to the clients at the reception counter. Some appeared quite impatient as their appointment times with my associate vet were not according to schedule.

Ethically, the vet should advise surgery as the only option and provide informed consent as to the anaesthetic risks or refer the owner to other vets if they do not do hamster anaesthesia and surgery.

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