Clinical Anesthesia and Analgesia in Fish

Fish have become a popular experimental model and companion animal, and are also farmed and caught for food. Thus, surgical and invasive procedures in this animal group are common, and this review will focus on the anesthesia and analgesia of fish. A variety of anesthetic agents are commonly applied to fish via immersion. Correct dosing can result in effective anesthesia for acute procedures as well as loss of consciousness for surgical interventions. Dose and anesthetic agent vary between species of fish and are further confounded by a variety of physiological parameters (e.g., body weight, physiological stress) as well as environmental conditions (e.g., water temperature). Combination anesthesia, where 2 anesthetic agents are used, has been effective for fish but is not routinely used because of a lack of experimental validation. Analgesia is a relatively underexplored issue in regards to fish medicine. However, recent studies have investigated opioid agents, nonsteroidal antiinflammatory drugs, and local anesthetics to determine their efficacy in minimizing pain and discomfort. The opioid morphine and the local anesthetic lidocaine do have significant effectiveness in reducing pain-related responses in rainbow trout (Oncorhynchus mykiss). Studies aimed at developing reliable analgesic protocols should explore a wide range of analgesic drug classes in several fish species.     

Anesthesia and Analgesia in Rabbits and Rodents

Rabbits and rodents are popular pets and are often presented to veterinarians for evaluation and medical treatment. Anesthesia in exotic pets is required for many diagnostic and surgical procedures and is associated with a higher perioperative risk in rabbits and rodents when compared with dogs and cats. Inhalation anesthetic agents are commonly used as the sole source of anesthesia in small rodents, whereas injectable agents in combination with inhalation anesthesia are often used for rabbits and larger rodents. Analgesia is an important component of exotic pet medicine. Although it may be difficult to recognize signs of pain in companion exotic mammals, adequate pain management should always be provided. Opioid and nonsteroidal antiinflammatory drugs are the analgesic medications of choice, but others should be considered (e.g., local anesthetic agents). This article provides an update of the current literature regarding anesthesia and analgesia in rabbits and rodents.     

Clinical Analgesia in Reptiles

Reptile pain and analgesia is only beginning to be understood in veterinary research and clinical medicine. The diversity of the class Reptilia also makes it difficult to extrapolate analgesic efficacy across species. Many veterinary clinicians argue that the administration of analgesic medication is risky to the patient and may mask behavioral signs of pain, which are considered evolutionarily adaptive for survival. However, veterinarians have an ethical obligation to treat painful conditions in all animals, including reptiles, because effective pain management reduces stress-induced disruption to homeostatic mechanisms and also decreases morbidity and mortality associated with trauma or surgery. Nevertheless, several obstacles limit successful analgesic use, including subjectivity of pain assessment, inadequate knowledge regarding analgesic efficacy across species, pharmacokinetics of analgesic drugs, and the unknown relationship between risks and benefits for this class of drugs. The objective of this review is to provide a current perspective on the practical application of analgesic medication in commonly maintained pet reptile species.     

Clinical Anesthesia in Reptiles

The clinical use of anesthetic agents in reptiles presents a number of unique challenges because of the diversity of the class Reptilia with respect to natural history, size, anatomy, and physiology. Reptiles are commonly maintained as companion animals, widely displayed in zoological institutions, and many species serve as subjects in laboratory facilities. Therefore, to become a skillful clinician, developing an understanding of anesthetic efficacy across reptile species is important. The objective of this review is to provide a current perspective on the practical application of anesthetic agents in commonly maintained pet reptile species.