It has been regularly used in veterinary medicine and was extensively used for surgical anaesthesia in the Vietnam War. When used as a recreational drug, it is found both in powder and liquid form, and is often referred to as "Special K" for its hallucinogenic and dissociative effects. Along with other psychotropic drugs, it is on the World Health Organizations List of Essential Medicines. It is available as a generic medication. Medical uses
Anesthesia
The use of ketamine in anesthesia reflects its characteristics. It is a drug of choice for short-term  procedures when muscle relaxation is not required. The effect of ketamine on the respiratory and circulatory systems is different from that of other anesthetics. It suppresses breathing much less than most other available anesthetics. When used at anesthetic doses, ketamine usually stimulates rather than depresses the circulatory system. Protective airway reflexes are preserved and it is sometimes possible to administer ketamine anesthesia without protective measures to the airways. Psychotomimetic effects limit the acceptance of ketamine; however, lamotrigine and nimodipine decrease psychotomimetic effects and can be counteracted also by benzodiazepines administered or propofol.Ketamine is frequently used in severely injured people and appears to be safe in this group. It has been widely used for emergency surgery in field conditions in war zones, for example, during the Vietnam War. A 2011 clinical practice guideline supports the use of ketamine as a sedative in emergency medicine, including during physically painful procedures. It is the drug of choice for people in traumatic shock who are at risk of hypotension.
A phase II clinical trial is underway to test the use of ketamine as an antidepressant for patients with Parkinson’s disease. Veterinary medicine
In veterinary anaesthesia, ketamine is often used for its anaesthetic and analgesic effects on cats, dogs, rabbits, rats, and other small animals. It is frequently used in induction and anaesthetic maintenance in horses. It is an important part of the "rodent cocktail", a mixture of drugs used for anaesthetising rodents. Veterinarians often use ketamine with sedative drugs to produce balanced anaesthesia and analgesia, and as a constant-rate infusion to help prevent pain wind-up. Ketamine is also used to manage pain among large animals. It is the primary intravenous anaesthetic agent used in equine surgery, often in conjunction with detomidine and thiopental, or sometimes guaifenesin.Ketamine appears not to produce sedation or anaesthesia in snails. Instead, it appears to have an excitatory effect. References
External links

Ketamine — from the U.S. National Library of Medicine (NLM) Drug Information Portal
Ketamine hydrochloride — from the U.S. National Library of Medicine (NLM)Drug Information Portal
Ketamine fact sheet — from the United States DEA, via Archive.org