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I. Purpose

This document provides guidelines for providing post-operative care and for recognizing and alleviating signs of pain and distress in rodents.

II. Scope

This applies to all individuals providing post-operative care and observations of post- operative rodents.

III. Guidance

The NRC Guide for the Care and Use of Laboratory Animals: states that an integral component of medical care is prevention or alleviation of pain associated with procedural or surgical protocols.  Pain is a stressor and can lead to unacceptable levels of stress and distress in animals.  Fundamental to the relief of pain is the ability to recognize its clinical signs in specific species, as species vary in their response to pain.

The NIH guidelines state that in general, unless the contrary is known or established, it should be considered that procedures that cause pain in humans may also cause pain in other animals.

IV. Responsibilities

The surgeon and research staff are responsible for: 

  1. Reading and following all of the post-operative care instructions in the IACUC protocol.
  2. Administration of analgesics, provision of supportive care and implementation of humane endpoints.
  3. It is the responsibility of the surgeon or an assigned lab member to visually observe the animal(s) daily (at least once every 24 hours), for a minimum of the first three days starting the day after surgery (day 0 is the day of surgery), or if treatments are provided and document the results in the post-operative log in the animal room.(see Rodent Survival Surgery Requirements, K) The post-operative log may not be completed (or prefilled) in advance of when the animals are observed. Failure to perform daily health observations constitutes protocol non-compliance and may result in loss privileges to work with laboratory animals at MSU. ARC staff will observe the animals and check the post-operative  log daily and are required to report any failure to comply with MSU standards to the IACUC. If, due to emergency, you are unable to check animals daily, you must arrange for another laboratory member to check the animals or promptly alert the ARC staff with a request that they check the animals on your behalf. Failure to check the health and welfare of the animals daily constitutes non-compliance and must be reported to the IACUC.
  4. Promptly notify the ARC Manager and/or the AV of any animal health problems. Food and water consumption of an individual animal as well as fecal and urinary output may be difficult to evaluate when rodents are group housed. However, evaluation of food and water consumption and fecal and urinary output must be performed daily as part of the overall health assessment. If you are not sure if the animal is eating and drinking, weigh the animal and compare to pre-operative weight.  Body weight is a sensitive indicator of dehydration or poor appetite.
  5. Contact the ARC staff if you observe signs of pain or distress that are not alleviated by analgesia given per protocol.

V. Post-Operative Care of Rodents

Provision of non-pharmacologic post-operative care, including nursing support, can assist with control of pain and promote well-being of the animal. Abnormalities noted during postoperative care, should be reported to the veterinarian.

  1. After surgery, animals should be housed in a clean, dry, and comfortable area, where they can be frequently observed by trained personnel.
  2. House rodents in clean cages. If animals have a surgical incision along the ventral thorax or abdomen, provide shredded paper towels for bedding. Paper towels allow for better observation of hemorrhage and prevent adhesion of bedding particles to the surgical site. Nesting material from the home cage should be added to the post-op cage to provide a familiar and supportive environment. If no incision complications are noted, animals can be returned to regular clean bedding the following day.
  3. Animals that have undergone survival surgery should not be placed in a cage with animals that have not had surgery. Animals that have not had surgery may attack and kill animals that have had surgery. 
  4. Depending on the type of surgical procedure and the social history of the animals, animals that have been successfully housed together prior to surgery and that have had the same surgery may be housed together after surgery. However, adult male mice that have been housed together prior to surgery and are separated for more than 24 hours should not be co-housed due to the tendency to fight upon reintroduction.
  5. Depending on the age, strain and sex of the animals, animals undergoing survival surgery may overgroom the surgical incision area of cage mates, resulting in removal of sutures and infection of the incisions site. Therefore, it may be necessary to house animals that have undergone thoracic or abdominal surgery individually for at least 3 days after surgery.
  6. Immediately after surgery, the cage should be set on a water circulating heating pad prior to the start of the surgical procedure so that it is warm when the animal is placed in the cage. Observe the animal until it is completely alert and mobile. The cage should be arranged such that one half of the cage is on the heating pad, allowing the animal to move away from the heat if it so desires. The cage should remain on the heating pad until the animals have had time to recover from hypothermia induced by exposure to anesthesia. In some cases, this may require that the cage be left on the heating pad overnight. Animals must never be placed in direct contact on an electric heating pad designed for domestic use by humans.
  7. Follow all specific post-operative care instructions in the approved animal protocol.
  8. If the rodent is unable to reach food in the modular food hopper, place a small number of food pellets on the floor of the cage.
  9. If the rodent is unable to reach the water bottle or water valve, moist food and a gel cup may be placed in the cage.
  10. Supplemental fluid injections may be required during the post-operative period if signs of dehydration are observed. A new needle must be used for each animal to prevent cross contamination. Adult mice may be given 1 ml of warmed sterile saline subcutaneously twice per day. Adult rats may be given 2.5 ml of warmed sterile saline subcutaneously per day.
    1. NOTE: Vials of sterile saline do not contain preservatives. Vials used for hydration support or to dilute medications must be dated when first opened and MUST BE DISCARDED after 3 days. The lack of preservatives in these solutions can enable bacterial growth and subsequent infection if injected into animals. Do not use (and immediately discard) open vials that do not display an "open" date written on the label.  All drugs administered parenterally must be mixed fresh (within 3 days of use) to reduce risk of contamination.
    2. Remove non-absorbable sutures or wound clips (if applicable) 7 – 14 days after surgery if the wound has healed.
    3. Immediately contact the ARC Animal Care technician, the ARC Manager, or the Attending Veterinarian if you observe any animal health problems or if you need assistance.

VI. Documentation

A written survival surgery/post-operative care log must be maintained in the animal housing room for the first 7 days after surgery and be available for review by the AV. The IACUC may also request copies of the documents. The log should include the following information:

  1. Surgery date
  2. Approved protocol number
  3. Name of surgeon
  4. Animal identification
  5. Type of surgery 
  6. Number of animals operated on and room/rack location
  7. Anesthetics and analgesics or other medications provided (e.g., antibiotics) including volume and dose (in mg/kg), time given, route of administration
  8. Animal condition (e.g., bright, alert, responsive, quiet but responsive)
  9. Surgical complications (describe and give corrective actions)

VII. Recognizing Signs of Pain and Distress in Rodents

  1. Animals should return to normal behavior as soon as possible following survival surgery. Signs of normal and abnormal behavior are listed below. The behavior of the animals must be evaluated for signs of pain or distress and the AV must be contacted immediately if signs of pain or distress other than noted in the IACUC protocol are observed.
  2. Addition of a small amount of nesting material to the cage can be used as a mechanism to evaluate mouse health and well-being. Mice that are free of pain will utilize the new nesting material within 30 minutes.
    Spontaneous behavior Sleeping, resting, digging, running, walking, rearing, climbing, eating, drinking, grooming, sniffing, nest making Writhing, back arching, hopping staggering, pressing, over-grooming incision site, no nest made
    Posture Lying, sitting, moving Hunched, crouched, tucked abdomen
    Breathing Regular, comfortable Exerted, irregular
    Coat Conditions Clean, well-groomed Unkempt, piloerection, hair loss
    Eyes Clear, bright Discharge, cloudy
    Body Condition Good Sunken flanks, distended abdomen
    Weight Loss < 10% of pre-operative body weight Loss > 10% of pre-operative body weight
    Incision Area Clean, dry, smooth, intact Red, swollen, discharge present
    Behavior after handling/weighing Alert, active Lethargic, increased vocalization
    Facial expression Relaxed (open eyes, ears forward) Grimace (ears pulled apart and back, eyes closed/tightened, whiskers standing on end)
  3. Additional clinical signs of rodents that should be reported to the ACF Manager and/or the Attending Veterinarian
    1. Bleeding
    2. Swelling or discharge from surgical site or other body parts
    3. Non-healing incision or removal of sutures/wound clops by animal too early
    4. Seizures
    5. Weakness or paralysis
    6. Dehydration
  4. Experimental End-Points
    1. The animal must be euthanized according to the humane end-points specified in the IACUC approved animal protocol.
    2. The ARC Animal Care Technicians, the ARC Manager and the Attending Veterinarian have the authority to require treatment or euthanasia if the animal is in pain or distress not covered by the humane endpoints stated in the IACUC approved animal protocol.

IACUC Approval Date: 08/18/2021

Review Date: 08/18/2021

Issue Date: 08/30/2021