Guidelines for Rodent Analgesia

Because the anatomic structures and neurophysiologic mechanisms leading to the perception of pain are similar in humans and non-human animals, it is reasonable to assume that if a stimulus:

  • is painful to humans,
  • is damaging or potentially damaging to tissues, or
  • induces escape and emotional responses in an animal,
  • it must be considered to be painful to that animal.


  • The choice of post-surgical analgesic drug must take into consideration (and be appropriate for) the estimated level and duration of post-surgical/post-procedural pain/discomfort associated with the specific surgery/procedure.

    Generally speaking, analgesics should be provided as early in the exercise as possible. Providing analgesic PRIOR to the initiation of the painful stimulus is most preferred; providing analgesia during the procedure (of an anesthetized animal) is considered the minimal standard when pre-procedural analgesia is not possible.

    This concept of pre-emptive analgesic is important to the stability of the research animal and the outcome of the research data. An additional benefit of pre-emptive analgesia is that the amount of anesthetics required for proper anesthesia are often reduced, further benefiting the animal with a rapid return to normal, while saving critical research dollars.

    For analgesic drugs that are administered via the oral route, the drug must:


  • be administered via oral gavage at the appropriate dosing frequency, or
  • if administered via the drinking water, the drug must be placed in the drinking water starting a minimum of 7 days prior to the surgery/painful procedure in order for the animal to be “exposed”, and, presumably, adapted to the altered taste of the water at the time of the surgery/procedure. This prepatory step is necessary to overcome ‘neophobia,’ a behavioral adaptation of rodents (especially rats) whereby they may not consume adequate quantities of fluids when a new taste sensation is recognized. Placing a flavored analgesic in the water post procedure may allow for association of the ‘pain’ with the new flavor and thereby rejection of the flavored water resulting in inadequate analgesia.
  • Duke utilizes a tiered system of analgesic delivery, based upon generalized observations of degrees of pain or discomfort. These include:


  • P1: Survival Surgery/Survival Procedures Estimated to Cause MARKED Post-Surgery/Post-Procedural Pain

    P2: Survival Surgery/Survival Procedures Estimated to Cause MODERATE Post-Surgery/Post-Procedural Pain

    P3: Survival Surgery/Survival Procedures Estimated to Cause MILD Post-Surgery/Post-Procedural Pain





    • P1: Survival Surgery/Survival Procedures Estimated to Cause MARKED Post-Surgery/Post-Procedural Pain. (Examples: any surgery involving thoracotomy or celiotomy; transplantation of an organ; limb amputation; extensive orthopedic surgery; cecal ligation and puncture):

    DRUG MOUSE RAT HAMSTER GERBIL GUINEA PIG
    Morhine 10 mg/kg SQ or IM every 4 hours 10 mg/kg SQ or IM every 4 hours 10 mg/kg SQ or IM every 4 hours 10 mg/kg SQ or IM every 4 hours 10 mg/kg SQ or IM every 4 hours
    Codeine 20 mg/kg SQ every 4 hours 50 mg/kg SQ every 4 hours 40 mg/kg SQ every 4 hours
    Oxymorphone 0.15 mg/kg SQ or IM every 4 hours 0.22-0.33 mg/kg SQ every 4 hours 0.2-0.5 mg/kg SQ or IM every 6 hours 0.2-0.5 mg/kg SQ or IM every 6 hours



    P2: Survival Surgery/Survival Procedures Estimated to Cause MODERATE Post-Surgery/Post-Procedural Pain
    Examples: most laparoscopic (i.e. intra-abdominal) surgeries; limited orthopedic surgery; intra-cranial surgery):

    DRUG MOUSE RAT HAMSTER GERBIL GUINEA PIG
    Ketoprofen 5mg/kg SQ SID 5mg/kg SQ SID 5mg/kg SQ SID 5mg/kg SQ SID 5mg/kg SQ SID
    Meperidine 20 mg/kg SQ or IM every 3 hours 20 mg/kg SQ or IM every 3 hours 20 mg/kg SQ or IM every 3 hours 20 mg/kg SQ or IM every 3 hours
    Nalbuphine 4-8 mg/kg SQ or IM every 3 hours 2-5 mg/kg SQ every 4 hours 4-8 mg/kg SQ or IM every 3 hours 4-8 mg/kg SQ or IM every 3 hours 1-2 mg/kg IM every 4 hours
    Pentazocine 10 mg/kg SQ every 4 hours 10 mg/kg SQ every 4 hours
    Butorphanol 2 mg/kg SQ every 4 hours 5 mg/kg SQ every 4 hours 5 mg/kg SQ every 4 hours 5 mg/kg SQ every 4 hours
    Buprenorphine 0.05-0.1 mg/kg SQ every 12 hours 0.1-0.5 mg/kg SQ every 12 hours 0.5 mg/kg SQ every 8 hours 0.2 mg/kg every 8 hours 0.05 mg/kg SQ every 12 hours
    Carprofen 5 mg/kg SQ every 12 hours 5 mg/kg SQ every 12 hours
    Aspirin 300 mg/kg orally every 24 hours 100 mg/kg orally every 24 hours 86 mg/kg orally every 24 hours
    Ibuprofen 7.5 mg/kg orally every 24 hours 30 mg/kg orally every 24 hours
    Phenylbutazone 30 mg/kg orally every 24 hours 20 mg/kg orally every 24 hours 40 mg/kg orally every 24 hours
    Acetaminophen 300 mg/kg orally every 24 hours 300 mg/kg orally every 24 hours



    P3: Survival Surgery/Survival Procedures Estimated to Cause MILD Post-Surgery/Post-Procedural Pain: (Examples: Placement of subcutaneous tumors or subcutaneous osmotic pumps; placement of chronic indwelling vascular cannulaes; orchiectomy)

    DRUG MOUSE RAT HAMSTER GERBIL GUINEA PIG
    Ketoprofen 5mg/kg SQ SID 5mg/kg SQ SID 5mg/kg SQ SID 5mg/kg SQ SID 5mg/kg SQ SID
    Flunixin 2.5 mg/kg IM every 12 hours 2.5 mg/kg IM every 12 hours
    Aspirin 300 mg/kg orally every 24 hours 100 mg/kg orally every 24 hours 86 mg/kg orally every 24 hours
    Ibuprofen 7.5 mg/kg orally every 24 hours 30 mg/kg orally every 24 hours
    Phenylbutazone 30 mg/kg orally every 24 hours 20 mg/kg orally every 24 hours 40 mg/kg orally every 24 hours
    Acetaminophen 300 mg/kg orally every 24 hours 300 mg/kg orally every 24 hours


    SQ=subcutaneous
    IM=intramuscular


    For purposes of administering a drug via the drinking water:

    MOUSE RAT HAMSTER GERBIL GUINEA PIG
    Normal* Daily Water Consumption 15 ml/100 gm body weight/day 8-11 ml/100 gm body weight/day 30 ml/day 4-7 ml/100gm body weight/day 10 ml/100 gm body weight/day


    *Animals that have been subjected to a painful procedure/surgery will not drink the “normal” amount of water for a minimum of 24 hours post-surgery/post-procedure. It is estimated that normal water consumption will be reduced by at least 50%.

    Amount of orally-administered drug to mix/administer per ml of drinking water:

    DRUG Rat- Normal Water Consumption Rat-50% Decrease in Water Consumption Mouse-Normal Water Consumption Mouse-50% Decrease in Water Consumption Guinea Pig-Normal Water Consumption Guinea Pig-50% Decrease in Water Consumption
    Aspirin 0.9 mg/ml 1.8 mg/ml 2 mg/ml 4 mg/ml 0.9 mg/ml 1.8 mg/ml
    Ibuprofen 0.3 mg/ml 0.6 mg/ml .05 mg/ml 0.1 mg/ml
    Phenylbutazone 0.2 mg/ml 0.4 mg/ml 0.2 mg/ml 0.4 mg/ml 0.4 mg/ml 0.8 mg/ml
    Acetaminophen 2.7 mg/ml 5.4 mg/ml 2.0 mg/ml 4.0 mg/ml



    Local Anesthetics: Even with general anesthesia, the topical, subcutaneous (at surgical incision site), intra-articular, etc. administration of a local anesthetic is recommended in order to provide additional post-surgical analgesia. Local anesthetics should not be used alone to provide post-surgical/post-procedural analgesia.

    Agent Potency (Procaine=1) Onset Duration* Topical Use Infiltration Use Nerve Block Use
    Procaine (Novacaine) 1 Slow 30-90 minutes - 1-2% 1-2%
    Chloroprocaine (Nesacaine) 2.4:1 Fast Up to 2 hours - 1-2% 1-2%
    Lidocaine (Xylocaine) 2:1 Fast 2 hours 2-4% 0.5-2% 0.5-2%
    Mipivacaine (Carbocaine) 2.5:1 Fast 2-4 hours - 1-2% 1-2%
    Tetracaine (Ponticaine) 12:1 Slow 3-8 hours 0.2% 0.1% 0.1%
    Hexycaine (Cyclaine) 1-2:1 Fast 3-6 hours 5% 0.5-1% 2%
    Bupivicaine (Marcaine) 8:1 Intermediate 24 -48 hours - 0.25% 0.5%


    * Duration is given for larger species. Duration in rodents (with their higher metabolic rate) should be considered less.