Analgesia

Absence of sensibility to pain, particularly the relief of pain without loss of consciousness.

Analgesic

An agent that relieves pain without causing loss of consciousness.

Anesthesia

Loss of feeling or sensation.

General Anesthesia

A controllable and reversible loss of consciousness induced by intoxication of the central nervous system. Lowered sensitivity to stimuli from the environment and diminished motor responses are major features of anesthesia

Basal Anesthesia

A light level of anesthesia or narcosis which may be produced by pre-anesthetic agents in order to lessen the amount of anesthetic agent required to produce anesthesia.

Surgical Anesthesia

General anesthesia with relaxation and analgesia sufficient to enable the safe performance of surgery.

Anesthetic

An agent used to produce anesthesia.

Anesthesiology

The study of the art and science of anesthesia.

Hypnotic

A term not commonly used in veterinary anesthesia. An agent which is used to induce sleep (a physiological state of unconsciousness from which a subject may be easily awakened by a wide variety of stimuli).

Narcosis

Depression of the central nervous system induced by a drug. Basal narcosis implies unconsciousness, analgesia and amnesia.

Narcotic (Opioid)

A drug that produces insensibility or stupor. The term is now generally used to describe a class of drugs such as morphine, its derivatives and synthetic agents which are addictive, analgesics, generally producing hypnosis but sometimes excitement and which occupy specific stereotaxic receptor sites in the central nervous system and other parts of the body.

Sedation

The allaying of irritability and excitement. Drowsiness is usually a feature.

Tranquilizer

A drug which allays anxiety without affecting clarity of consciousness. Ataractic is another term which is used for a tranquilizer as is neuroleptic. In veterinary medicine tranquilizers are frequently used in doses high enough to cause sedation and the terms tranquilizers and sedative are often incorrectly used interchangeably.

Neuroleptanalgesia

A state of altered awareness, usually sedation, accompanied by analgesia and produced by a combination of a neuroleptic (tranquilizer) and a narcotic analgesic.

Neuroleptanesthesia

The condition of neuroleptanalgesia where another agent, usually nitrous oxide, is added to produce sleep and a state of surgical anesthesia.

Apneustic Respiration

A respiratory pattern where there is a sustained inspiratory effort and the respiratory pause is on inspiration rather than on expiration as in the normal respiratory pattern.

Catalepsy

A state of diminished responsiveness characterized by a trance-like state and constantly maintained immobility usually with rigidity.

Dissociative Anesthesia

This is a state of anesthesia produced by cyclohexamines and related compounds (e.g. ketamine hydrochloride) which are analgesic and which produce a state resembling catalepsy. The effects on the central nervous system are a combination of depression and excitation. The usual depression of certain reflexes, which are used as signs of anesthesia, is not always present.

Pain

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Pain is a perception that depends on activation of a discrete set of receptors (nociceptors) by noxious stimuli eg thermal, chemical or mechanical. Further processing in neural pathways eg spinal cord, brain stem, thalamus and cerebral cortex, enables noxious stimuli to be perceived as pain. Pain perception varies according to site, duration, and intensity of the stimulus and can be modified by previous experience, emotional states and innate individual differences.

Pain Detection Threshold

The lowest intensity of a stimulus that is perceived as pain or that induces a response. (uniform across species)

Pain Tolerance Threshold

The highest intensity of a stimulus which will be tolerated voluntarily. This is more species specific and subject to behavioral modification.

Anxiety and Fear

Emotional states involving increased arousal and alertness prompted by an unknown or known danger.

Stress

The effect of physical, physiologic or emotional factors (stressors) that induce an alteration in the animal's homeostasis or adaptive state. May involve changes in the neuroendocine function, in the autonomic nervous system, in the mental state of the animal as well as in its behavior.

Distress and suffering

Inability to adapt to an altered environment leading to an unpleasant emotional response.

Discomfort

Minimal changes in an animal's homeostasis due to changes in the environment.