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Office of Animal Care and Use
Phone: (919) 966-5569
Fax: (919) 966-8429
CB 7193
Chapel Hill, NC 27599-7193
iacuc@med.unc.edu
The UNC-Chapel Hill IACUC requires scientific justification to allow researchers to conduct multiple surgeries on most species of animals. The Committee does, however, make an exception when considering oocyte collection in amphibians.
Three survival and one non-survival surgeries are allowed in amphibians at this institution. While creating this policy, the IACUC considered the following: requirement to obtain good quality oocytes, appearance of distress in the animals, the length of the surgery, and the absence of adhesions on necropsy. Also, unlike land vertebrates, amphibian abdominal muscles are not used as heavily for support. This fact reduces the likelihood that a laparotomy causes severe pain as in other vertebrates.
Tricaine methanesulfonate (MS222) is commonly used to anesthetize amphibians. Place the animal in a container of this solution and observe her closely during induction. Drowning during both induction and recovery is possible. Tilting the induction container to keep the nares out of the water helps avoid drowning. Once the amphibian has reached a surgical plane of anesthesia remove her from the induction container. A nonabrasive sterile drape moistened with the anesthetic and placed over part of the amphibian's body helps maintain a surgical plane and keeps the animal's skin from drying. Depth of anesthesia may also be maintained by dripping some of the liquid anesthetic on the amphibian's body.
Surgeries to remove oocytes must be done under aseptic conditions. A single skin prep of very dilute 0.5% povidine iodine solution or 0.75% chlorhexidine should be applied using a nonabrasive, sterile material. Be careful not to injure the skin which is covered with a protective mucous layer. Avoid all soaps, scrubs, and full strength solutions. The instruments must be sterile and the surgeon must wear sterile gloves. The incision should be closed with a nonwicking suture, e.g. nylon. Close the muscle and skin layer separately.
To speed recovery from anesthesia, you may gently rinse the amphibian in a small amount of water from the home tank. Place the amphibian in a shallow container during recovery. Using water from the animal's home tank helps reduce stress. After full recovery from anesthesia (approximately 24 hours) the animal may be returned to her home tank.
Post-operative care should be provided as with any species. Suggested analgesics for xenopus are butorphanol, 25 mg/kg intracelomic, or xylazine, 10 mg/kg intracelomic. Both butorphanol and xylazine have a calming effect (Terril-Robb et. al., 1996).
Keep precise records on each animal. Include the date of surgery and any drugs, e.g. analgesics, given. Rest the animal a minimum of eight weeks between surgeries and rotate surgical sides.
References: Much of this information was gathered through conversations with Dr. Dorcas Schaeffer, ACLAM veterinarian at University of Tennessee, Knoxville and the recently published Guidance on the Housing and Care of the African Clawed Frog, Royal Society for the Prevention of Cruelty to Animals.