Animal Watering

Potable water from municipal water treatment plants is commonly used for laboratory animals on the assumption that if it is good enough for humans it is good enough for laboratory animals; however, this is not necessarily so. It is possible that potable water may contain chemical contaminants at a level too low to be considered toxic, but that may be at high enough levels to confound study results when given to laboratory animals. The use of reverse osmosis (RO) to consistently provide high-quality drinking water for the animals greatly reduces the potential for such and therefore is rapidly becoming the standard. In addition, because water quality and content varies from community to community, the use of RO water provides a practical and economical means of standardizing drinking water for research animals throughout the world. It is common to acidify

Figure 8.25 Figures 8.25a and 8.25b each picture a double door pass through bulk autoclave. The autoclave pictured in Figure 8.25a has sliding doors and is not pit mounted, thus requiring a lift in order to load and unload carts and cage racks. The autoclave in Figure 8.25b has hinged doors and is pit mounted, which greatly facilitates loading and unloading. A steel plate bridges the gap between the floor of the autoclave and the facility floor. This autoclave has the capacity to hold three of the type of mouse rack shown in the figure. Note the exhaust hood in the ceiling above the autoclave door in Figure 8.25b.

Figure 8.25 Figures 8.25a and 8.25b each picture a double door pass through bulk autoclave. The autoclave pictured in Figure 8.25a has sliding doors and is not pit mounted, thus requiring a lift in order to load and unload carts and cage racks. The autoclave in Figure 8.25b has hinged doors and is pit mounted, which greatly facilitates loading and unloading. A steel plate bridges the gap between the floor of the autoclave and the facility floor. This autoclave has the capacity to hold three of the type of mouse rack shown in the figure. Note the exhaust hood in the ceiling above the autoclave door in Figure 8.25b.

animal drinking water, especially water delivered to the animals in bottles, to a pH of 2.5 to 3 in order to limit the growth of microorganisms in the water during the time between bottle changes, particularly if the bottles are to be changed less frequently than every 3 to 4 days. Hyperchlorination up to 10 ppm also effectively limits microorganism growth, but it tends to dissipate from water in a bottle within a few days.

There are two commonly used methods to provide water to laboratory animals: in glass or polycarbonate bottles with holes in the bottle or equipped with stainless steel sipper tubes or through automatic watering devices. Both systems have pros and cons. Water bottles are labor intensive, needing to be exchanged with freshly sanitized bottles at least weekly and, if not acidified, at least two times a week.

Automatic watering devices have a relatively high front-end cost and also present a quality control challenge because of biofilms that form on the inside of the distribution system and bacterial growth that can and does build up in the water of the low-pressure low-flow distribution system, especially in dead end segments and in the rack water manifolds. The quality of automatic watering valves has greatly improved in recent years, reducing the problem of cage flooding from leaking watering valves, but this problem has not been totally eliminated. Of course, water bottles can also leak their contents into the cage, and while it will not flood the cage with water, it will soak the bedding material and deprive the animals of water. Choosing a watering strategy is a critical decision that needs to be made early in the facility planning process.44,45

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