A rat Functional Observational Battery (FOB) is a standardized set of behavioral tests used in toxicology and pharmacology studies to evaluate the neurobehavioral effects of chemicals, drugs, or environmental exposures in rats.

Purpose:

The primary goal of a rat FOB is to detect neurotoxicity—that is, whether a substance negatively affects the central or peripheral nervous system. It's commonly used in regulatory safety assessments for new pharmaceuticals, pesticides, and industrial chemicals.

 What It Measures:

The FOB evaluates a range of behaviors and physical signs, typically grouped into three domains:

1. Autonomic and Physiological Functions

• Lacrimation (tear secretion)

• Piloerection (hair standing up)

• Salivation

• Pupillary response (miosis/mydriasis)

• Respiratory pattern

• Body temperature

2. Neuromuscular and Motor Activity

• Gait and posture

• Grip strength (usually forelimbs)

• Hindlimb splay

• Righting reflex

• Tremors, twitches, or convulsions

• Locomotor activity (open field test)

3. Sensorimotor and Behavioral Responses

• Response to handling or stimulus (e.g. touch, sound)

• Startle response

• Tail pinch response

• Approach or avoidance behavior

• Signs of aggression or hypoactivity

• Visual placing or pupil response

How It’s Done:

• Rats are typically observed at baseline (pre-dose) and at multiple post-dose time points (e.g., 30 minutes, 1 hour, 1 day, etc.).

• The observations are often made in a standardized testing arena or using specific instruments (like grip strength meters or locomotor activity chambers).

• Observations are systematic and semi-quantitative—using scoring systems to assess severity (e.g., 0 = normal, 1 = mild, 2 = moderate, etc.).

 Importance in Safety Testing:

• Part of OECD Test Guideline 424 (Neurotoxicity Testing).

• Required by regulatory agencies like the FDA, EPA, and OECD.

• Helps determine No Observed Adverse Effect Levels (NOAELs) and supports risk assessment.