(b) "Dangerous dog" does not include a police work dog, as defined in subdivision eighteen of this section, which acts in the manner described in this paragraph while such police work dog is being used to assist one or more law enforcement officers in the performance of their official duties. 25. "Working search dog" means any dog that is trained to aid in the search for missing persons and is actually used for such purpose. 26. "Therapy dog" means any dog that is trained to aid the emotional and physical health of patients in hospitals, nursing homes, retirement homes and other settings and is actually used for such purpose, or any dog during the period such dog is being trained or bred for such purpose, and does not qualify under federal or state law or regulations as a service dog. 27. "Detection dog" means any dog that is trained and is actually used for such purposes or is undergoing training to be used for the purpose of detecting controlled substances, explosives, ignitable liquids, firearms, cadavers, or school or correctional facility contraband. 28. "Physical injury" means impairment of physical condition or substantial pain. 29. "Serious physical injury" means physical injury which creates a substantial risk of death, or which causes death or serious or protracted disfigurement, protracted impairment of health or protracted loss or impairment of the function of any bodily organ.