Llama Sedation

Although the words “sedation” and “anesthesia” are often used interchangeably, in the clinical sense, there is a distinct difference between the two. Sedation is a pharmacologically-induced depression of consciousness during which an animal cannot be easily aroused, but may respond to certain types of stimuli. Anesthesia is a pharmacologically-induced reversible state of amnesia, analgesia, loss of responsiveness and loss of skeletal muscle reflexes.

Sedation is associated with a decreased risk for complications in many species, so it is often considered in place of general anesthesia.¹ The comparative safety of sedation over general anesthesia in human and animal patients is also well-documented. The use of sedation in exotic animals is often the result of the perception of greater risk in using anesthesia, particularly in those that have undergone the stress of capture.

Additional advantages of sedation include a reduction in anxiety and stress, and for better diagnostic sampling and therapeutics. In some cases, the risk of handling must be weighed against the risk of foregoing diagnostic testing or procedures, or the risk of general anesthesia.¹

The Llama: Biology and Background

The llama (Lama glama) is a member of the camel family (Camelidae). This group of animals, whose native range is the South American Andes, is also known as lamoids or New World camelids. Llamas and other lamoids have been so widely domesticated over the last several thousand years that there are few occurring in the wild. Today, domesticated llama herds are found in the Andean highlands of the western South American continent. They are also farmed, primarily for their fleece, in a number of other countries around the world.^3,4

Like camels, lamoids originated in North America over 40 million years ago, with lamoids migrating to South America and camels migrating west via the Bering Strait and later becoming extinct in North America.^2,3 Unlike camels, llamas and other lamoids do not have the iconic back humps that make camels so easily recognizable.

Llamas are the largest of the New World camelids. They are slender-bodied, with long legs, long necks, short tails and large ears. They average 45 inches in height at the shoulder; adult males weigh between 300 and 400 pounds, and adult females weigh between 230 and 350 pounds.³ While most llamas are white in color, they may also be solid black or brown, or white with brown or black markings.

Llamas are efficient pack animals, and have long been used by the Andean people to carry goods and supplies through difficult mountain regions. A 250 pound llama is able to carry a load of 100 to 130 pounds for around 15 to 20 miles a day. When a llama is burdened with too much weight however, it will sit down and refuse to move until their load is reduced. Llamas are also used for food, wool, hides, tallow for candles, and dried dung for fuel.²

Llamas are grazing animals; in their native range, they feed mostly on grass. Like cows, llamas regurgitate their food and chew it as cud. Unlike cows however, they are pseudo ruminants with a three-chambered stomach (unlike true ruminants such as cows, which have four-chambered stomachs). Llamas can also survive on other plants, and require little water. Llamas breed in the late summer and fall. Their gestation period is approximately 11 months, after which the female gives birth to one young.³

Sedation Risks in the Llama

Given their level of domestication, camelids like llamas are easy to handle, thus physical restraint and local anesthetic techniques are frequently used to provide immobility and analgesia. General anesthesia techniques are similar to those for ruminants and horses. Regurgitation of compartment one (C1) of the stomach contents (which can occur in chemically-immobilized ruminants), postoperative nasal congestion and associated respiratory distress postextubation are potential hazards associated with the chemical immobilization of llamas.⁷ Observation and monitoring of palpebral and ocular reflexes, eyeball position, and pupil size can be used to monitor the depth of anesthesia.

Other risks associated with the capture of llamas include hypothermia, hyperthermia, frostbite, bloat, respiratory depression/arrest and cardiac arrest. Usually however, recovery from sedation in llamas is uneventful.^6,9

Disadvantages of sedation versus anesthesia in llamas can include:

• Incomplete elimination of patient movement
• Patient semi-awareness
• Lack of complete analgesia

The most obvious risk in such cases is an increased danger to handlers. These disadvantages can be overcome with careful dosing and monitoring, effective patient handling and efficient use of analgesics when procedures are expected to produce discomfort.⁵

The American College of Veterinary Anesthetists (ACVA) has published recommendations for monitoring animals that are sedated without general anesthesia:

• Palpation of pulse rate, rhythm and quality
• Observation of mucous membrane color and CRT
• Observation of respiratory rate and pattern
• Auscultation
• Pulse oximetry, supplemental oxygen, and endotracheal tube (where applicable) and materials to obtain vascular access should be readily available¹

Finally, it should be noted that intubation (general anesthesia) is recommended for any camelid that needs to be immobilized for procedures lasting longer than 20 minutes.⁷

Agents for Sedation of the Llama

Sedatives produce effects that are usually required during transportation and for minor procedures (e.g., calmness, loss of aggression, loss of alertness). In this condition, the llama is not fully immobilized and may respond to various disturbances. Thus, sedatives are usually used singly for only very minor procedures, or as adjuncts to anesthetics. The synergistic effect of sedatives and anesthetics is far greater than the individual effect of either of the two drug classes in attaining smooth induction, good muscle relaxation and smoother recovery.⁶

Sedatives that are often used in veterinary medicine include drugs such as acepromazine, midazolam, alprazolam, amitriptyline, buspirone, clomipramine, dexmedetomidine, diazepam, fluoxetine, lorazepam, paroxetine, sertraline, or trazodone. ^6,8 Midazolam is used in human and veterinary medicine for the purposes of pre-anesthesia and sedation and has a wide margin of safety in many species. When combined with an opioid, its effects are synergistic, allowing a reduction of the amount of either drug.⁵ Dosages most commonly used are 0.5-10 mg/kg, combined with an opioid (butorphanol, buprenorphine, hydromorphone, other). Effects are variable, from slight decrease in activity to lateral recumbency. These effects are likely related to species variability in response and the varying dose rates suggested for different species/groups. In all cases, animals can still react somewhat to handling and noxious stimuli.⁶

When midazolam is used alone, sedation may be adequate in ruminants, camelids and several other species. When used in combination with other drugs (e.g., opioids, ketamine, acepromazine, dexmedetomidine), midazolam provides more reliable sedation. It should be noted that use of sedation and manual restraint alone is inappropriate for any procedure expected to produce discomfort. In llamas, additional sedation can be provided with sub-anesthetic dosages of ketamine, 2-7 mg/kg, or alfaxalone, 1 mg/kg IM. If additional immobilization is essential, low concentrations of inhalant gas can be considered.⁹

The drugs used for sedating llamas may vary depending upon the preference and experience of the veterinarian or wildlife management personnel. Much of the literature suggests that dosing higher when in doubt is in fact safer than dosing conservatively, in that there is more risk to a partially-immobilized animal and to human handlers than there is to a heavily-dosed animal.^8,9 This is primarily due to the improved safety of modern drug formulations, which allow for much more latitude in dosing without a significant increase in risk factors.