Quarantine Housing Of Animals Imported From Nonvendor Sources

If the supplier of animals for an experimental facility is unable to supply a health report or the containment facilities at this supplier are regarded unsatisfactory, animals should not be introduced directly into an experimental facility. This problem has increased with the increased use of transgenic animals, as many of these animals, mostly mice, are not produced by commercial breeders but are produced by a range of different research groups, who globally exchange these animals between them. Therefore, especially university animal facilities currently receive requests from their animal users to receive transgenic mice from different sources, the health status of which can be difficult to judge. Taking into account that these transgenic animals are often costly and difficult to get for restocking if they are accidentally lost, animal facilities need to take precautions to reduce the risk of infections in their animals, while still allowing the intake of mice from a number of different sources. This is most efficiently done by breeding animals on site in a barrier-protected unit into which animals are only introduced by rederivation.

To get a smaller number of animals into experiments on a current basis, it may become necessary to create a facility in which it is possible to quarantine animals before entry into the main experimental facility. Here the animals should be maintained for at least 4 weeks before health monitoring is performed to define the status of these animals. If sentinels are used, and this will often be the case, 4 weeks of quarantine may be insufficient. If this health monitoring states the absence of unwanted microorganisms, the animals may be transferred to the experimental facility. In larger institutional units, animals are delivered currently and, therefore, each delivery needs to be kept separate inside the quarantine facility, which makes the use of negative pressure isolators or IVC systems the most appropriate choice for quarantine housing. Furthermore, one sampling for health monitoring can never be made 100% safe, and it may, therefore, be the safest for units dealing with many minor deliveries from different sources, if all delivered animals are routinely rederived to the institution's own barrier breeding facility and only from a breeding stock inside this unit delivered to individual projects in the experimental facilities. This may, of course, prove to be impossible for all animals, and, in practice, it may become necessary to differentiate deliveries into safe and unsafe deliveries. Animals from known commercial breeders with high standard barrier facilities and efficient health monitoring procedures may be considered safe deliveries, and therefore allowed direct access to the experimental facility, eventually through a quarantine unit, while all other animal deliveries are regarded unsafe and subjected to rederivation. This method would not take into consideration that animals may get infected during transport. Another security measure would be to divide the experimental unit into small separate units, which are protected from one another in a way, that will secure that they each can be regarded as their own microbiological entity, i.e., they should have their own barrier and staff. Inside each separation all animals should derive from the same source.

Which system to set up must be judged independently by each institution, which needs to weigh the costs of the protective measures against the economic value of their experiments.

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