Respiratory Arrest in Llamas During Capture and Chemical Immobilization

The llama (Lama glama) is a domesticated herd animal with a range encompassing the high Andes of South America. Llamas are related to camels (family (Camelidae) and are sometimes called New World camelids or lamoids, a group that includes llamas, alpaca, guanaco and vicuñas. Based on the fossil evidence, scientists believe that all camelids originated in North America, and that one group moved north several million years ago, crossing the Bering land bridge and evolving into camels, while others migrated south and became New World camelids.¹

Llamas are the largest of the New World camelids. They are slender-bodied, with long legs, long necks, short tails and large ears. An adult llama averages 45 inches in height at the shoulder, with adult males weighing between 300 and 400 pounds, and adult females weighing between 230 and 350 pounds.^2,3

Most New World camelids have been so widely domesticated that many species, such as llamas and alpacas, have ceased to exist in the wild. Since they are the largest of the New World camelids, llamas are used chiefly as pack animals by locals. An adult llama can be loaded with around 50 to 75 pounds, and can carry this weight while covering up to 20 miles a day. Pack trains of llamas can include several hundred animals, and regularly move large amounts of goods over the treacherous Andean terrain.²

Like the smaller alpaca, llamas are also valued for their fleece. As a result, llama farming has become popular worldwide, particularly in North America and Europe. In South America, leather is also made from llama hides; the wool is made into ropes, rugs, and fabrics. Interestingly, llamas and alpacas are able to breed with one another and produce fertile offspring. This suggests that both species may have stemmed from the wild guanaco (Lama guanicoe), which is believed to be the parent species of the llama.³

The llama’s natural environment is at high altitude and is relatively cool. On farms in more temperate regions, a llama’s health will benefit from periodic shearing if they live where summers are hot. A llama needs about three inches of its fleece for winter warmth, so a llama sheared to one inch in the spring can grow an adequate coat by the time winter comes.³

In their natural environment, llamas graze on grasses and leaves. They are adaptive feeders, however; on farms, they will eat grasses, shrubs, trees and hay. Three to five llamas can be grazed per acre, and a bale of hay will feed an adult llama for around a week.²

Llamas are not particularly vocal animals, but they do use vocalizations on occasion. Females “hum” to their offspring, and males emit a type of gurgling sound, often during breeding. Breeding males will “yell” at each other, and if a llama perceives danger, it will put out alarm call to warn the rest of the herd.^1,2 In the wild, the dominant male typically scouts from a high vantage point to watch over the herd, vocalizing if danger arises.

Respiratory Arrest Risks in the Llama

Wildlife management personnel, llama farmers and veterinarians are often called upon to chemically immobilize llamas for medical treatment, research, relocation and the like. Respiratory arrest in llamas during chemical immobilization can occur due to drug overdose, but it can happen as a spontaneous adverse reaction to immobilizing drugs. Central nervous system disorders can also cause hypoventilation leading to respiratory arrest.¹

In cases where respiratory arrest is brought on by chemical immobilization, the decreased respiratory effort reflects central nervous system (CNS) impairment due to the immobilizing drugs. Drugs that decrease respiratory effort include opioids and certain sedatives. Certain combinations of drugs can increase the risk for respiratory depression, although some of the newer species-specific formulations can actually lower the risk of complications, including respiratory depression and arrest. Opioid-induced respiratory depression (ORID) is usually most common risk factor in the immediate postoperative recovery period, but it can persist and lead to catastrophic clinical outcomes.¹

Chemical Immobilization and Respiratory Arrest in Llamas

Respiratory arrest is characterized by the complete cessation of breathing. There are several approaches available to alleviate respiratory arrest in llamas as a result of chemical immobilization. Antagonists (also known as reversal agents) are able to reverse the effects of opioid anesthetics and tranquilizers; these have been some of the most notable pharmacological developments in wildlife immobilization. ^6-8 These drugs are able to completely reverse anesthetic effects and return an animal to a normal physiological state. The benefits of antagonists include preventing predation in the wild after anesthetic events and avoiding complications. Antagonists also decrease the personnel and equipment time needed for monitoring immobilized animals through their recovery. It should be noted that intubation is recommended for llamas being anesthetized for longer than 20 minutes.⁴

In cases of respiratory arrest, the goal is to restore adequate ventilation and oxygenation without further compromising an already compromised cardiovascular situation.⁶ In the event of respiratory arrest in an immobilized llama, of course the administration of all immobilizing drugs should be ceased. Naltrexone is frequently used to fully reverse opioid-based immobilization after capture, especially if the animal needs to be released back into the field and must be fully alert. If residual analgesic or sedative effects are required, partial opioid antagonists or mixed agonists/antagonists can be used for the reversal of opioids such as diprenorphine, nalorphine or butorphanol.^7,8 Atipamezole is often used as a reversal agent for medetomidine and dexmedetomidine in order to reduce their sedative and analgesic effects. It has also been used for the reversal of other alpha-2 adrenergic agonists (e.g., xylazine, clonidine, tizanidine and brimonidine).⁶

Potassium channel blockers such as doxapram can be used to stimulate breathing in llamas suffering from respiratory depression or arrest. Doxapram is widely used as a respiratory stimulant in veterinary medicine, and has been shown to increase the minute ventilation in large herbivores immobilized with etorphine.⁷ The use of oxygen is recommended during llamas immobilization whenever possible, since it can lower the risk of respiratory arrest occurring. It can also be combined with partial opioid reversal agents to better alleviate hypoxia.⁶