Veterinary anesthesia
Encyclopedia
Veterinary anesthesia is anesthesia
performed on animals (excluding humans) by a veterinarian
. Anesthesia is used for a wider range of circumstances in animals than in people, due to animals' unwillingness to cooperate with certain diagnostic or therapeutic procedures. Veterinary anesthesia includes anesthesia of the major species: dogs, cats, horses, cattle, sheep, goats, and pigs, as well as all other animals requiring veterinary care such as birds, pocket pet
s, and wildlife.
. The ACVA was recognized by the AVMA in 1975, despite attempts by the AVMA to include anesthesia as a subspecialty of surgery or medicine. As of 2010, there are 192 Diplomates of the ACVA. To become an ACVA board-certified Diplomate, veterinarians must have at least one year of clinical practice experience followed by three years of anesthesia residency training under the supervision of ACVA Diplomates, have accepted for publication a scientific peer-reviewed
research article
, and passed both a written and oral examination.
In Europe, the European College of Veterinary Anaesthesia and Analgesia (ECVA) is one of 21 specialty organizations recognized by the European Board of Veterinary Specialisation. As of February 2011, there are 111 ECVA Diplomates.
is safer than anesthesia without a technician. In most private veterinary practices, the technician administers and monitors anesthesia with supervision from the attending veterinarian. In many academic institutions, anesthesia technicians are involved in working with and teaching veterinary students as well as supervising anesthetized cases. The Academy of Veterinary Technician Anesthetists is a provisional specialty academy of the North American Veterinary Technician Association and is responsible for licensing technicians as being specialized in anesthesia. For a technician to become specialized, they must be a licensed technician in their state, accumulate 6000 hours of work in veterinary medicine (at least 75% of which must be in anesthesia), 40 hours of continuing education related to anesthesia, demonstrate proficiency in anesthesia skills, and pass a comprehensive written examination.
, bone marrow sampling, and occasionally ultrasound
. Aggressive animals may require anesthesia in order to handle and perform a physical exam or obtain blood for testing. Exotic animals frequently require anesthesia for simple procedures (such as taking a radiograph or catheter placement) due to lack of domesticity. Animals may require anesthesia for therapeutic procedures, such as urinary catheterization
to relieve obstruction, injection into a mass, or removing fluid from the eye to treat glaucoma.
In addition to anesthesia, analgesia is often managed by anesthesiologists or is included in the considerations for anesthesia.
and an opioid
will permit less inhalant
anesthesia to be used, improving cardiovascular stability. A one-year study in a teaching hospital shows that dogs and cats typically experience a 1 in 9 chance of anesthetic complications, with a 1 in 233 risk of death. A larger-scale study states the risk of death in healthy dogs and cats as 1 in 1849 and 1 in 895 respectively. For sick dogs and cats, it was 1 in 75 and 1 in 71 respectively. For rabbits, the risk were 1 in 137 and 1 in 14 respectively for the healthy and sick groups.
). Other procedures in horses require general anesthesia using an inhalant anesthetic. Horses, due to their complex physiology as performance animals, suffer a number of difficulties that can complicate anesthesia. This results in horses having a higher risk of perioperative fatality - approximately 1 in 100.
Most procedures in ruminants can be performed standing under sedation and/or local anesthesia. This strategy is manageable due to the types of procedures being performed, the larger size of the patient, the relative difficulty of general anesthesia, and the cost of the procedure versus the product value of the animal.
and sevoflurane
. Injectable drugs such as sedatives or tranquilizers are often used in these patients to facilitate induction and maintenance of anesthesia.
used in human medicine are used in veterinary medicine. Alpha-2 receptor
agonist
drugs such as xylazine
, romifidine
, detomidine
, and medetomidine
, are used frequently in veterinary species (particularly large animal), but are rarely used in people. Guaifenesin
is used as a muscle relaxant prior to anesthesia induction in some animals. Propofol
is commonly used in small animal anesthesia, however it is rarely used in large animals due to the cost. 'Propoclear' is also commonly used in smaller branches of small animal surgery as it has a longer shelf life once opened than propofol
whilst essentially having the same properties. Butorphanol
is rarely used in people but is commonly used in all species. Ketamine
, used in children for anesthesia, is used extensively in many species to induce anesthesia or cause heavy sedation. Expensive agents, such as etomidate
and desflurane
are rarely used outside of university hospitals. Different species have different responses to drugs. For example, horses may experience mania with morphine
whereas dogs typically become sedated. Rabbits and guinea pigs are well sedated with midazolam
, which can occasionally excite dogs and cats.
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
performed on animals (excluding humans) by a veterinarian
Veterinarian
A veterinary physician, colloquially called a vet, shortened from veterinarian or veterinary surgeon , is a professional who treats disease, disorder and injury in animals....
. Anesthesia is used for a wider range of circumstances in animals than in people, due to animals' unwillingness to cooperate with certain diagnostic or therapeutic procedures. Veterinary anesthesia includes anesthesia of the major species: dogs, cats, horses, cattle, sheep, goats, and pigs, as well as all other animals requiring veterinary care such as birds, pocket pet
Pocket pet
Pocket pet is a term used to refer to any small mammal commonly kept as a household pet. The six general criteria which qualify an animal to be considered a pocket pet are:# its commonality as a domestic housepet...
s, and wildlife.
Specialization in anesthesia
In North America, the American College of Veterinary Anesthesiologists is one of 20 specialty organizations recognized by the American Veterinary Medical AssociationAmerican Veterinary Medical Association
The American Veterinary Medical Association , founded in 1863, is a not-for-profit association representing more than 81,500 U.S. veterinarians working in private and corporate practice, government, industry, academia, and uniformed services....
. The ACVA was recognized by the AVMA in 1975, despite attempts by the AVMA to include anesthesia as a subspecialty of surgery or medicine. As of 2010, there are 192 Diplomates of the ACVA. To become an ACVA board-certified Diplomate, veterinarians must have at least one year of clinical practice experience followed by three years of anesthesia residency training under the supervision of ACVA Diplomates, have accepted for publication a scientific peer-reviewed
Peer review
Peer review is a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant field. Peer review methods are employed to maintain standards, improve performance and provide credibility...
research article
Academic publishing
Academic publishing describes the subfield of publishing which distributes academic research and scholarship. Most academic work is published in journal article, book or thesis form. The part of academic written output that is not formally published but merely printed up or posted is often called...
, and passed both a written and oral examination.
In Europe, the European College of Veterinary Anaesthesia and Analgesia (ECVA) is one of 21 specialty organizations recognized by the European Board of Veterinary Specialisation. As of February 2011, there are 111 ECVA Diplomates.
Anesthesia technicians
Evidence exists that suggests that anesthesia which is supervised by a qualified technicianVeterinary technician
In North America, the principle paraveterinary workers are called veterinary technicians or veterinary technologists-Job description:Technical skills include:...
is safer than anesthesia without a technician. In most private veterinary practices, the technician administers and monitors anesthesia with supervision from the attending veterinarian. In many academic institutions, anesthesia technicians are involved in working with and teaching veterinary students as well as supervising anesthetized cases. The Academy of Veterinary Technician Anesthetists is a provisional specialty academy of the North American Veterinary Technician Association and is responsible for licensing technicians as being specialized in anesthesia. For a technician to become specialized, they must be a licensed technician in their state, accumulate 6000 hours of work in veterinary medicine (at least 75% of which must be in anesthesia), 40 hours of continuing education related to anesthesia, demonstrate proficiency in anesthesia skills, and pass a comprehensive written examination.
Application in animals
Anesthesia is required for many surgical procedures which require the patient to be immobile, unaware, and without pain. In addition, certain diagnostic procedures require anesthesia, notably stomach or airway endoscopyEndoscopy
Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an endoscope , an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ...
, bone marrow sampling, and occasionally ultrasound
Medical ultrasonography
Diagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions...
. Aggressive animals may require anesthesia in order to handle and perform a physical exam or obtain blood for testing. Exotic animals frequently require anesthesia for simple procedures (such as taking a radiograph or catheter placement) due to lack of domesticity. Animals may require anesthesia for therapeutic procedures, such as urinary catheterization
Urinary catheterization
In urinary catheterization , a latex, polyurethane or silicone tube known as a urinary catheter is inserted into a patient's bladder via his or her urethra. Catheterization allows the patient's urine to drain freely from the bladder for collection. It may be used to inject liquids used for...
to relieve obstruction, injection into a mass, or removing fluid from the eye to treat glaucoma.
In addition to anesthesia, analgesia is often managed by anesthesiologists or is included in the considerations for anesthesia.
Techniques in small animals
Cats and dogs are frequently anesthetized for surgical procedures. Small animals are most often placed under general anesthesia due to the types of procedures typically performed, the small size of the patient, their suitability to general anesthesia, and the greater degree of control. A balanced anesthesia protocol can be used whereby different drugs with different effects are used so that a high dose of just one drug can be avoided. For example, combining a sedativeSedative
A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....
and an opioid
Opioid
An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...
will permit less inhalant
Inhalant
Inhalants are a broad range of drugs whose volatile vapors are taken in via the nose and trachea. They are taken by volatilization, and do not include drugs that are inhaled after burning or heating...
anesthesia to be used, improving cardiovascular stability. A one-year study in a teaching hospital shows that dogs and cats typically experience a 1 in 9 chance of anesthetic complications, with a 1 in 233 risk of death. A larger-scale study states the risk of death in healthy dogs and cats as 1 in 1849 and 1 in 895 respectively. For sick dogs and cats, it was 1 in 75 and 1 in 71 respectively. For rabbits, the risk were 1 in 137 and 1 in 14 respectively for the healthy and sick groups.
Techniques in horses and ruminants
Many procedures can be performed on the standing horse with heavy sedation alone. Some procedures may require general anesthesia due to the location of surgery (for example, castrationGelding
A gelding is a castrated horse or other equine such as a donkey or a mule. Castration, and the elimination of hormonally driven behavior associated with a stallion, allows a male horse to be calmer and better-behaved, making the animal quieter, gentler and potentially more suitable as an everyday...
). Other procedures in horses require general anesthesia using an inhalant anesthetic. Horses, due to their complex physiology as performance animals, suffer a number of difficulties that can complicate anesthesia. This results in horses having a higher risk of perioperative fatality - approximately 1 in 100.
Most procedures in ruminants can be performed standing under sedation and/or local anesthesia. This strategy is manageable due to the types of procedures being performed, the larger size of the patient, the relative difficulty of general anesthesia, and the cost of the procedure versus the product value of the animal.
Exotic pets
Anesthesia of exotic animals (Guinea pigs, rabbits, birds) is challenging and the higher peri-anesthetic mortality in these species compared to dogs and cats, attests to this fact. These animals are challenging to anesthetize for a number of reasons: very little research has been carried out on safe and effective drug doses for specific species; exotic pets often 'hide' the fact that they are sick and by the time owners realize how sick the pet is the course of the disease is far advanced; the unique anatomy and physiology of exotic pets poses challenges for anesthetic management. For example, the anatomy of the respiratory system of birds, Guinea pigs, and reptiles makes it difficult to induce and maintain anesthesia solely with inhalation agents such as isofluraneIsoflurane
Isoflurane is a halogenated ether used for inhalational anesthesia. Together with enflurane and halothane, it replaced the flammable ethers used in the pioneer days of surgery. Its name comes from being a structural isomer of enflurane, hence they have the same empirical formula...
and sevoflurane
Sevoflurane
Sevoflurane , also called fluoromethyl hexafluoroisopropyl ether, is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used for induction and maintenance of general anesthesia. Together with desflurane, it is replacing isoflurane and halothane in modern anesthesiology...
. Injectable drugs such as sedatives or tranquilizers are often used in these patients to facilitate induction and maintenance of anesthesia.
Anesthetic agents
Most anesthetic agentsAnesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
used in human medicine are used in veterinary medicine. Alpha-2 receptor
Adrenergic receptor
The adrenergic receptors are a class of metabotropic G protein-coupled receptors that are targets of the catecholamines, especially noradrenaline and adrenaline ....
agonist
Agonist
An agonist is a chemical that binds to a receptor of a cell and triggers a response by that cell. Agonists often mimic the action of a naturally occurring substance...
drugs such as xylazine
Xylazine
Xylazine is a drug that is used for sedation, anesthesia, muscle relaxation, and analgesia in animals such as horses, cattle and other non-human mammals. An analogue of clonidine, it is an agonist at the α2 class of adrenergic receptor....
, romifidine
Romifidine
Romifidine is a drug that is used in veterinary medicine as a sedative mainly in large animals such as horses, although it may be used in a wide variety of species. It is not used in humans, but is closely related in structure to the commonly used drug clonidine.Romifidine acts as an agonist at the...
, detomidine
Detomidine
Detomidine is an imidazole derivative and α2-adrenergic agonist, used as a large animal sedative, primarily used in horses. It is usually available as the salt detomidine hydrochloride...
, and medetomidine
Medetomidine
Medetomidine is a synthetic drug used as both a surgical anesthetic and analgesic often used as the hydrochloride salt medetomidine hydrochloride. It is a crystalline white alpha-two adrenergic agonist that can be administered as an intravenous drug solution with sterile water...
, are used frequently in veterinary species (particularly large animal), but are rarely used in people. Guaifenesin
Guaifenesin
Guaifenesin INN or guaiphenesin , also glyceryl guaiacolate, is an expectorant drug sold over the counter and usually taken by mouth to assist the bringing up of phlegm from the airways in acute respiratory tract infections.-History:Similar medicines derived from the guaiac tree were in use as a...
is used as a muscle relaxant prior to anesthesia induction in some animals. Propofol
Propofol
Propofol is a short-acting, intravenously administered hypnotic agent. Its uses include the induction and maintenance of general anesthesia, sedation for mechanically ventilated adults, and procedural sedation. Propofol is also commonly used in veterinary medicine...
is commonly used in small animal anesthesia, however it is rarely used in large animals due to the cost. 'Propoclear' is also commonly used in smaller branches of small animal surgery as it has a longer shelf life once opened than propofol
Propofol
Propofol is a short-acting, intravenously administered hypnotic agent. Its uses include the induction and maintenance of general anesthesia, sedation for mechanically ventilated adults, and procedural sedation. Propofol is also commonly used in veterinary medicine...
whilst essentially having the same properties. Butorphanol
Butorphanol
Butorphanol is a morphinan-type synthetic opioid analgesic developed by Bristol-Myers. Brand name Stadol was recently discontinued by the manufacturer. It is now only available in its generic formulations, manufactured by Novex, Mylan, Apotex and Ben Venue Laboratories. Butorphanol is most...
is rarely used in people but is commonly used in all species. Ketamine
Ketamine
Ketamine is a drug used in human and veterinary medicine. Its hydrochloride salt is sold as Ketanest, Ketaset, and Ketalar. Pharmacologically, ketamine is classified as an NMDA receptor antagonist...
, used in children for anesthesia, is used extensively in many species to induce anesthesia or cause heavy sedation. Expensive agents, such as etomidate
Etomidate
Etomidate is a short acting intravenous anaesthetic agent used for the induction of general anaesthesia and for sedation for short procedures such as reduction of dislocated joints, tracheal intubation and cardioversion...
and desflurane
Desflurane
Desflurane is a highly fluorinated methyl ethyl ether used for maintenance of general anesthesia. Like halothane, enflurane and isoflurane, it is a racemic mixture of and optical isomers...
are rarely used outside of university hospitals. Different species have different responses to drugs. For example, horses may experience mania with morphine
Morphine
Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...
whereas dogs typically become sedated. Rabbits and guinea pigs are well sedated with midazolam
Midazolam
Midazolam is a short-acting drug in the benzodiazepine class developed by Hoffmann-La Roche in the 1970s. The drug is used for treatment of acute seizures, moderate to severe insomnia, and for inducing sedation and amnesia before medical procedures. It possesses profoundly potent anxiolytic,...
, which can occasionally excite dogs and cats.