T u l a n e U n i v e r s i t y I A C U C Guidelines for Rodent & Rabbit Anesthesia, Analgesia and Tranquilization & Euthanasia Methods Abbreviations: General Considerations IV = intravenous SC = subcutaneous IH = inhalation = intramuscular qxh = every X hours IP = intraperitoneal PO = per os, oral The proper use of anesthetics, analgesics and tranquilizers is important not only for humane and scientific reasons, but also for compliance with federal law (Animal Welfare Act) and Public Health Service Policy. No one drug or administering technique is best in all cases, and the choice of the most appropriate drug and administering method should follow consideration of both practical (e.g. type and length of operation or experiment, training and experience of assistants, instrumentation available) and physiological factors (animal species, strain or breed, age, sex, weight, health status). The guidelines that follow are not a comprehensive list of available drugs/methods. They are intended to be recommendations for using relatively safe and readily available drugs for routine procedures in the common laboratory animal species. For each species, recommendations are categorized into pre-medication, induction, inhalants, and analgesics. Proper drug doses may vary greatly depending on species, strain, sex, age, physiologic status of the animal, and the level of anesthesia/analgesia desired. Pre-medication and Sedation Pre-medication before general anesthesia provides a smoother induction of and recovery from anesthesia. Furthermore, it permits use of a reduced dosage of the induction and maintenance anesthetics and provides a balanced anesthesia. Anticholinergics (Atropine, Glycopyrrolate) can be administered before anesthesia to reduce salivary and airway secretions and to prevent bradycardia. Perioperative Management In small mammals, body temperature in particular is very important. Due to the greater ratio of body surface to bodyweight, small mammals easily get hypothermic. By closely Guidelines for Rodent & Rabbit Anesthesia, Analgesia and Tranquilization & Guidelines for Euthanasia 1 of 1
monitoring body temperature and the judicious use of heating pads, heating lamps, waterfilled gloves or aluminum foil, severe hypothermia can be prevented. During anesthesia, fluids such as NaCl or Lactated Ringers should be administered at a rate of 10 ml/kg/h (doses can vary depending on preexisting dehydration or relevant study criteria). If intravenous access cannot be accomplished, fluids can be administered subcutaneously or intraperitoneally. Duration of and recovery from anesthesia should be kept as short as possible. Oxygen saturation should be monitored during recovery. In case the animal is unable to maintain a physiologic saturation, oxygen should be substituted. Analgesia Assessing the degree of pain or discomfort experienced by an animal can be difficult and the assessment inaccurate. While the physiologic mechanisms of pain perception are similar in all mammalian species, the ability to tolerate and cope with pain may be vastly different in different species. For example, prey species such as rodents have adapted to hide overt signs of pain to avoid signaling weakness to a predator. Therefore, a rodent or rabbit experiencing mild to moderate pain may display no clinical signs of discomfort. Moderate to severe pain in rodents frequently leads to changes in normal physiology or behavior. Accurate recognition of these changes requires that research personnel have some knowledge of normal behavior and physiology for the species they are using. Analgesic drugs include opioids (e.g., Buprenorphine) or non-steroidal anti-inflammatory drugs (NSAIDs, e.g., Carprofen, Meloxicam). Inhalatory anesthesia with isoflurane is the technique of choice for most procedures due to ease of administration and relative safety. Anesthetic induction is rapid, with little or no distress, and applying a simple facemask easily performs maintenance of anesthesia. The anesthetic potency of isoflurane is similar to that in larger species; therefore the values of inspired concentrations of these halogenated agents are similar. Low doses of these agents allow minor procedures, and high doses may produce deeper anesthesia. However, side effects of these drugs, such as decrease in cardiac output and hypotension, are very strong when using high doses, and careful monitoring of vital signs is required. Furthermore, data being measured during the procedure can be altered by low blood pressure and low cardiac output. Investigators should consider this possibility. Opioids can be given to provide intraoperative analgesia and to reduce the amount of inhalatory anesthetics needed to provide surgical anesthesia. Recovery from inhalatory anesthesia is rapid. Potential signs of pain and distress (All or some may be present) Rodents 1. A marked decrease in activity 2. Porphyrin (red) staining around the eyes, nose, and sometimes on the forepaws (from grooming this material from the face; rats particularly) 3. Aggression or vocalization (squeak or chattering) when handled 4. Excessive licking or scratching of a painful area 5. Favoring a limb or other part of the body 6. Shuddering or twitching, arching or stretching the back 7. Unkempt appearance, huddling in a cage corner 8. Changes in behavior with cagemates 2 of 2
Rabbits 1. Hunched appearance 2. Decreased activity 3. Ruffled hair coat 4. Increased aggression or vocalization when handled 5. Defense of the painful area 6. Pupil dilatation 7. Teeth grinding 8. Vocalization RAT SPECIES INFORMATION Physiologic parameters: Body temperature = 35.9-37.5 C Heart rate = 250-450/min Respiratory rate = 70-115/min Tidal volume = 0.6-2.0 ml Premedication Atropine 0.05-0.4 mg/kg SC, Glycopyrrolate 0.01-0.02 mg/kg SC, Acepromazine 0.5-2.5 mg/kg Induction/Maintenance 60-100 mg/kg, IP + Xylazine 5-10 mg/kg 50 mg/kg IP + Medetomidine 0.5 mg/kg 75 mg/kg IP + Acepromazine 2.5 mg/kg Telazol 20-40 mg/kg IP Pentobarbital 50-80 mg/kg IP Propofol 10 mg/kg IV Isoflurane 4-5% induction in 100% oxygen 1-2% maintenance in 100% oxygen Analgesics Opioids Morphine 2-5 mg/kg every hour SC Buprenorphine 0.01-0.05 mg/kg q 6-12 h SC Butorphanol 2 mg/kg q 4 SC 3 of 3
Non-Opioids Aspirin 100 mg/kg q 4 h PO Carprofen 5 mg/kg q 12 h SC, PO Meloxicam 1-2 mg/kg q 12h SC, PO Flunixin 1.1 mg/kg q 12 h SC, Ibuprofen 10-30 mg/kg q 4 h PO Acetaminophen 100-300 mg/kg q 4 h PO MOUSE SPECIES INFORMATION Physiologic parameters: Body temperature = 36.5-38.0ºC Heart rate = 325-780/min Respiratory rate = 94-163/min Tidal volume = 0.09-0.23 ml Premedication Atropine 0.04-0.05 mg/kg SC, Glycopyrrolate 0.01-0.02 mg/kg SC Acepromazine 0.5-2.5 mg/kg, IP Pentobarbital 3-4 mg/100 g IP Induction/Maintenance 80-110 mg/kg + Xylazine 5-10 mg/kg 50 mg/kg + Xylazine 5 mg/kg + Acepromazine 0.5 mg/kg IP, IP, 50 mg/kg SC, IP + Medetomidine 0.5 mg/kg Pentobarbital 5-9 mg/100 g IP Telazol 45 mg/kg + Xylazine 7.5 mg/kg Isoflurane 4-5% induction in 100% oxygen 1-2% maintenance in 100% oxygen 4 of 4
Analgesics Opioids Morphine 2-5 mg/kg q 2-4 h SC Buprenorphine 0.05-0.1 mg/kg q 6-12 SC Butorphanol 1-5 mg/kg q 4 h SC Oxymorphone 0.05 mg/kg q 2-4 h SC, Non-Opioids Aspirin 120 mg/kg q 4 h PO Carprofen 2 mg/kg q 12 h SC, PO Meloxicam 1-2 mg/kg q 12h SC, PO Flunixin 2.5 mg/kg q 12 h SC, Ibuprofen 7.5 mg/kg q 4 h PO Acetaminophen 300 mg/kg q 4 h PO Rabbit SPECIES INFORMATION Physiologic parameters: Body temperature = 38-39.6ºC Heart rate = 130-325/min Respiratory rate = 32-60/min Tidal volume = 4-6 ml/kg Rabbits have serum atropinesterase that antagonizes atropine rapidly and therefore causes reduced response. If needed, glycopyrrolate should be used. Premedication Glycopyrrolate 0.1 mg/kg SC Acepromazine 0.25-1 mg/kg SC, Diazepam 0.5-5 mg/kg IV,, IP Midazolam 2 mg/kg IV,, IP Induction/Maintenance Propofol 5-10 mg/kg 35 mg/kg + Xylazine 5 mg/kg 25 mg/kg + Medetomidine 0.5 mg/kg Telazol 5-25 mg/kg Isoflurane 4-5% induction in 100% oxygen 1-2% maintenance in 100% oxygen 5 of 5
Continuous Rate Infusions (IV) Propofol Propofol 0.5-1-1.5 mg/kg/min 0.5-0.7 mg/kg + Fentanyl 5 µg/kg loading dose 0.3-0.6µg/kg/min infusion Analgesics Opioids Buprenorphine 0.01-0.05 mg/k q 6-12 h SC,, IV Butorphanol 0.1-0.5 mg/kg q 4 h SC,, IV Morphine 2-5 mg/kg q 2-4 h SC,, IV Oxymorphone 0.2 mg/kg shorter duration than Morphine Non-Opioids Ketoprofen 1-3 mg/kg q 12-24 h Carprofen 1.5 mg/kg q 12 h PO Meloxicam 0.2-0.3 mg/kg q 24 h PO Ibuprofen 10-20 mg/kg q 4 h IV Euthanasia Methods All euthanasia methods approved by the Tulane University IACUC are described in the 2000 Report of the AVMA Panel on Euthanasia. Below please find a table of the common methods used at the Department of Comparative Medicine: Species Method Dosage Mice, Rats, and CO2 Inhalation See DVSR SOP 3.5 Guinea Pigs Pentobarbital 100 mg/kg IV, IP Rabbits Beuthanasia Pentobarbital Beuthanasia 1ml/10 lbs. of body weight IV 100 mg/kg IV 1ml/10 lbs. of body weight IV 6 of 6