earned in the task as well as any supplements given. Careful observation of the animal's 
behavior and regular clinical monitoring of the animal's health are critical for ensuring 
successful application of fluid control procedures. 
Body weights should be monitored several times weekly. Animals under water control may 
lose weight over time due to reduced food consumption. Food should be given in close 
temporal proximity to the access to fluid (e.g., immediately after the session). Monitoring the 
amount of food consumed daily is a quick way to determine if adequate fluid intake is 
occurring. A plan of action should be in place in advance and implemented in case weights 
decline to unhealthy levels under a fluid control regimen. 
REGULATING THE TASTE AND CHEMICAL COMPOSITION 
OF FOOD AND FLUIDS 
Experiments may require manipulation of food or fluid intake in order to study hunger, thirst, 
taste, and olfactory senses. Methods for these experiments have been summarized (Wellman 
and Hoebel, 1997). For example, a two-choice preference test would offer the animal two 
containers, one with plain food or fluid, the other with a test substance added (Cunningham 
andNiehus, 1997). Special diets should be evaluated for spoilage and degradation. Record- 
keeping is critical. Pre-printed forms help to ensure consistent recording of the lot number of 
each diet, the amount consumed, body weight, and notes about the animal's appearance, 
equipment problems, departures from the protocol, and so on. Methods for presenting drugs 
and other experimental chemicals in the food and water are discussed in Chapter 6, 
Pharmacological Studies. 
A FINAL NOTE ON FOOD AND FLUID CONTROL 
When beginning work with a new species, consult with the laboratory animal veterinarian as 
well as recent literature for that species before designing protocols that require restriction of 
food or water. When the study begins, be prepared to consider and address a range of 
behavioral, environmental, or equipment-related variables that might hinder training or 
disrupt performance. Inexperienced personnel may presume that a source of problems in 
training or maintaining a food- or fluid-motivated behavior is that the restriction is not strict 
enough (or, in some cases, that it is too strict). The other types of variables that should be 
considered first, however, are equipment malfunctions, programming errors, task criteria that 
are raised rapidly or set too high for the animal's level of training, illness, or nonprogrammed 
water restriction (in the case of food-motivated behavior). In all circumstances, careful 
monitoring of animals under food or fluid control is necessary every day to avoid additional 
nonprogrammed restriction. ■ 
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