Guide for the Care and Use of Laboratory Animals - Office of ...

86 GUIdE FOR ThE CARE ANd USE OF LAbORATORy ANIMALSDisinfection is usually accomplished through water treatment (e.g.,filtration and application of UV light or ozone) and/or water changes. Chlorineand most chemical disinfectants are inappropriate for aquatic systemscontaining animals as they are toxic at low concentrations; when used todisinfect an entire system or system components, extreme care must betaken to ensure that residual chlorine, chemical, and reactive byproductsare neutralized or removed. The type of monitoring and frequency variesdepending on the disinfection method, the system, and the animals.Algal growth is common in aquatic systems and increases with thepresence of nitrogen and phosphorus, particularly in the presence of light.Excessive growth may be an indication of elevated nitrogen or phosphoruslevels. Algal species seen with recirculating systems are generally nontoxic,although species capable of producing toxins exist. Algae are typicallyremoved using mechanical methods (i.e., scrubbing or scraping). Limitingalgal growth is important to allow viewing of the animals in the enclosure.Cyanobacteria (commonly called blue-green algae) growth is also possibleand may be common in freshwater aquaculture. The same factors that promotealgae growth also promote cyanobacteria growth. As with algae, whilemost species are harmless, some species can produce clinically relevanttoxic compounds (Smith et al. 2008).Tank (cage) changing and disinfection are conducted at frequencies usingmethods that often differ from terrestrial systems. Because waste is dissolvedin the water and/or removed as solids by siphoning or filtration, regularchanging of tanks is not integral to maintaining adequate hygiene in typicalaquatic systems. The frequency of cleaning and disinfection should be determinedby water quality, which should permit adequate viewing of the animals,and animal health monitoring. System components such as lids on fishtanks, which may accumulate feed, may require sanitation as often as weeklydepending on the frequency and type of feed and the system’s design.Cleaning and disinfection of the Macroenironment As with terrestrialsystems, all components of the animal facility, including animal rooms andsupport spaces (e.g., storage areas, cage-washing facilities, corridors, andprocedure rooms), should be regularly cleaned and disinfected as appropriateto the circumstances and at a frequency determined by the use ofthe area and the nature of likely contamination. Cleaning agents should bechosen and used with care to ensure there is no secondary contaminationof the aquatic systems.Cleaning implements should be made of materials that resist corrosionand withstand regular sanitation. They should be assigned to specific areasand should not be transported between areas with different risks of contaminationwithout prior disinfection. Worn items should be replaced regularly.The implements should be stored in a neat, organized fashion that facilitatesdrying and minimizes contamination or harborage of vermin.