Osmotic Pumps in Mice and Rats

BU IACUC Approved April 2011, Revised January 28, 2014, Revised July 2019

Osmotic pumps are miniature infusion pumps for the continuous dosing of laboratory animals. These minipumps provide researchers with a method for controlled and continuous agent delivery in vivo. Osmotic pumps can be used for systemic administration when implanted subcutaneously or intraperitoneally. They can be attached to a catheter to provide targeted delivery for intravenous, intraarterial, intracerebral, or cranial/calvarial infusion. The pumps can be used to target delivery to a variety of sites including direct substance administration to cord, spleen, liver, organ or tissue transplants. A single pump may provide up to four weeks of infusion.

A. The use of an osmotic pump must be approved in the IACUC protocol.
B. Alternative to repeated SC or IP administration

The Principal Investigator (PI) is encouraged to consider implantation of osmotic pump as an alternative to repeated SC or IP administration.

C. Side effects and toxicity

Any side effects or toxicity that may occur due to the compound being infused must be stated in the IACUC protocol.

D. Biological material

Any Biological Material being infused must be certified to be murine pathogen free (SPF) or tested according to the IACUC Policy for Biological Materials in Rodents.

E. Variation from standard procedures

If the study requires some variation from these Standard Procedures, the variation must be described in the protocol and approved by the IACUC.

F. Duration of pump use

The protocol must identify the number of days the pump will be in place. The pumps cannot be left implanted indefinitely. At the end of their delivery period, they swell and begin to leak a concentrated salt solution, resulting in local irritation to tissues around the pump and can also induce reverse osmosis, resulting in dehydration of tissues or of the whole animal. If the protocol mandates survival of the animal after 1.5 X (days or weeks) of the designated delivery period, the time of explant must be stated in the IACUC protocol and must be no later than one half-life (t1/2) after the completion of its infusion time. See Explanting Osmotic Pumps, in the Procedures section of this page.

In animals surviving after the pump’s active infusion time, the pump must be removed no later than one half-life (t1/2) after the completion of its infusion time. Thus, a pump designed for one week’s infusion must be removed no later than 3 1/2 days after the end of the 7th day or 10 1/2 days after the implant. A pump designed for two weeks’ infusion is removed no later than one week after the end of the two weeks or three weeks after implant.

G. Wound clips or ligatures in the skin must be removed in 10-14 days if the animals are to survive longer than 2 weeks.
H. One osmotic pump per animal may be implanted.

If more than one pump is sequentially implanted, the protocol must describe and justify the implantation of more than one pump.

I. Pumps are to be implanted with the animal under general anesthesia.

The animals must be anesthetized following the BU IACUC Policy for Anesthesia and Analgesia in Research Animals.

J. Analgesia

Analgesia must be provided at the time of implantation and explant & replacement, according to the BU IACUC Policy for Anesthesia and Analgesia in Research Animals.

K. Monitoring

The animal must be monitored daily for a minimum of 72 hours and up to one week following surgery, assessing such parameters as appetite and wound healing. Administer analgesics and other drugs as stipulated in the protocol or as recommended by the veterinarian using the Rodent Postprocedure Monitoring Form to document care during recovery.

L. Animals must be monitored for side effects due to the infusate.
M. Aseptic surgical technique

Pumps must be implanted using aseptic surgical technique following the BU IACUC Policy for Survival Surgery in Rodents.

N. Size of the pump to be used should be determined following the Manufacturer’s guidelines3, 4
O. Sterility

Pumps are supplied sterile and sterility must be maintained throughout the implantation procedure. Solutions to be infused via the pump must be sterile.

P. It is possible to decontaminate, sterilize and reuse some osmotic pumps5



A. Subcutaneous Implantation


B. Intraperitoneal Implantation


C. Intravenous or Intraarterial Infusion (via the External Jugular Vein or Carotid Artery) in Rats & Mice


D. Cranial or Intracerebral Infusion


E. Explanting Osmotic Pumps


BU IACUC Approved April 2011, Revised January 28, 2014
Post-Procedure Monitoring Form

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