Aspiration in Llamas During Capture and Chemical Immobilization
The llama (Lama glama) is a domesticated animal that is descended from the wild guanaco (Lama guanicoe). Their range encompasses the high Andes mountains of South America. Llamas are camelids (Camelidae); they are related to camels and are sometimes called New World camelids or lamoids, a group that includes llamas, alpaca, guanaco and vicuñas. Fossil evidence indicates that all camelids originated in North America, and it is believed that one group moved north, crossing the Bering land bridge and evolving into camels, while others migrated south and became New World camelids.1
Llamas are slender-bodied, with long legs, long necks, short tails and large ears. They average 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
Llamas and other New World camelids have been widely domesticated; in fact, many lamoid species have ceased to exist in the wild, while their domesticated descendants are flourishing. Being the largest of this group of animals, llamas are used chiefly as pack animals by locals. In most cases, an adult llama can be saddled with loads of 50 to 75 pounds. Carrying such weight, they can cover up to 20 miles in a day. Pack trains of llamas can include several hundred animals, and regularly move large amounts of goods over the rough Andean terrain.2 Sometimes, a llama carrying too heavy a load will refuse to move, lie on the ground and spit, hiss, or kick until the load is lessened. Apart from this, llamas are known for being very easy to manage.
Like their smaller cousins, the alpaca, llamas are highly valued for their fleece. As a result, llama farming has become popular worldwide, particularly in North America and Europe. The llama’s natural environment in the South American Andes is at high altitude and is relatively cool. Thus, a llama’s health will benefit from periodic shearing if they live where summers are hot. Llamas vary considerably in fleece length and thickness, so the importance and frequency of shearing depends on the individual animal and the climate. 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 South America, leather is also made from llama hides, and the wool is made into ropes, rugs, and fabrics.
In their natural environment, the llama is a grazer and browser, with a diet consisting of grasses and leaves. Llamas 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
Like other camelids, llamas are not particularly loud animals, but they do vocalize on occasion. Llamas occasionally emit a humming noise. Females will hum to their offspring, and males “orgle,” which is 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 his herd of females. If danger arises, he will “yell” out an alarm, which spurs other males in the herd to do likewise.
Aspiration Risks for Llamas
The needs of zoo, wildlife management, farm and research personnel regularly require the chemical immobilization of llamas. This puts these animals at risk for complications that can arise from chemical immobilization, including vomiting and subsequent aspiration. Camelids, like other ruminants, have certain special requirements for sedation and anesthesia (see below). Attention to these requirements can significantly mitigate the risk of complications.
Aspiration occurs when a foreign substance (e.g., food, liquid, or other materials) enters the airway or lungs. This can give rise to serious health problems, such as aspiration pneumonia. Aspiration can occur when a human or animal has difficulty swallowing normally (this is referred to as dysphagia), but it can be brought on during or after anesthetic events.
When food is swallowed, it passes from the mouth into the pharynx (throat), progressing through the esophagus into the stomach via peristaltic action. The pharynx is also involved in transmitting air to the lungs; upon inhalation, air enters through the nose or mouth and progresses into the pharynx, then moving into the trachea and lungs.
In cases where dysphagia is present in an animal, small amounts of food or fluids may be inadvertently aspirated. When this occurs in the conscious animal, the aspirate is usually cleared through coughing. In the case of anesthetic aspiration, an animal vomits food from their stomach during a surgical procedure, which is then aspirated into the lungs. This potentially represents a much larger volume of food and/or fluids being aspirated, which can lead to serious complications. Postoperative nausea and vomiting (PONV) is common in humans and other mammals,3 but intraoperative aspiration (aspiration during a surgical procedure), is very dangerous and can lead to fatality.4
Llamas and Chemical Immobilization
The chemical immobilization of animals is a method of rendering them tractable while using a minimal of restraint. In the field, the research or wildlife management objectives are usually to measure or weigh an animal, collection of blood or tissue for research or diagnostics, marking an individual or fitting a radio transmitter for studying migration patterns, range requirements and behavior patterns or the translocation of animals.4,5 These requirements have resulted in the development of increasingly safer methods in chemical immobilization. With the pioneering work on the chemical immobilization of wildlife that took place from the 1950s on, chemical immobilization techniques have improved greatly through the development of increasingly efficacious drugs and equipment.5
Despite their size, llamas are usually agreeable when it comes to handling given the extent of their domestication. Thus, physical restraint and local anesthetic techniques are often used to provide immobility and analgesia. Anesthesia techniques are similar to those for ruminants and horses.6,7 Regurgitation of compartment one (C1) of the stomach contents (similar to what can occur in true ruminants), postoperative nasal congestion and associated respiratory distress postextubation are potential hazards associated with llama anesthesia.8,9
The utilization of basic veterinary knowledge can make a substantial contribution to the llama’s safety during capture and chemical immobilization. Teams that are qualified to handle llamas should have the appropriate expertise in wildlife anesthesia and should include an attending veterinarian when appropriate. The chemical restraint exercise is not complete until the animal is fully recovered and back in its environment.
Anesthetic Aspiration in Llamas
When foreign substances such as stomach contents make their way into an animal’s lungs, they can damage lung tissues, resulting in acid-associated pneumonitis or other bacterial infection. Until formulated drugs (e.g., combinations of α2-agonists such as medetomidine, detomidine, xylazine and their reversal agents) came into use in recent years, opioids were the mainstay of wildlife anesthesia.5 As with other mammals, problems encountered with certain opioids in llamas are known to include vomiting or passive regurgitation that can lead to aspiration pneumonia.
Fasting prior to an anesthetic event (periprocedural fasting) has historically been recommended by clinicians because of the risk of vomiting and aspiration. Unfortunately, this is often impractical or impossible under field conditions. Additionally, much of the data on anesthetic aspiration relates to humans receiving general anesthesia, however, many other mammals have been known to aspirate during procedures while under sedation, even where no intubation or general anesthesia were employed.
Preventing and Managing Aspiration in Llamas
In preparing llamas for anesthesia and surgery, decreasing the size and pressure in C1 before anesthesia is essential, as well as withholding food for 12 to 18 hours and withholding water for up to 12 hours. Withholding food or water in neonates is not recommended, as this increases the risk of dehydration and hypoglycemia. The literature states that llamas younger than one month of age rarely regurgitate during anesthesia. It is also recommended that llamas be orotracheally-intubated for procedures lasting more than 20 minutes.9
In helping to prevent anesthetic aspiration, the available literature recommends histamine (H2) antagonists such as cimetidine, famotidine, nizatidine, and ranitidine and proton pump inhibitors (PPIs) such as dexlansoprazole, esomeprazole, lansoprazole, omeprazole, pantoprazole, and rabeprazole, which have been shown to be effective in increasing the pH and reduce the volume of gastric contents.5 Prokinetics such as domperidone, metoclopramide, erythromycin and renzapride promote gastric emptying and are also believed to reduce the risk of aspiration.4
In the event that a llama aspirates under sedation or anesthesia, the first step in management is the immediate recognition of gastric content in the oropharynx or the airways. The llama should be positioned with the head down and rotated laterally if possible. Orotracheal and endotracheal suctioning is indicated, either before or after orotracheal intubation. It is recommended that the airway be secured as rapidly as possible to prevent further contamination and to facilitate airway clearance.5 Flexible bronchoscopy may be used as an adjunct to orotracheal and endotracheal suctioning. If particulate matter is present in the airway, rigid bronchoscopy may be required.5,8
4 Shaikh, Safiya Imtiaz et al. Postoperative nausea and vomiting: A simple yet complex problem. Anesthesia, essays and researches vol. 10, 3 (2016).
5Nason, K. Acute Intraoperative Pulmonary Aspiration. Thoracic surgery clinics vol. 25,3 (2015): 301-7.
6Lance, W. Exotic Hoof Stock Anesthesia and Analgesia: Best Practices. In: Proceedings, NAVC Conference 2008, pp. 1914-15.
7Kluger M.T., et. al. Crisis management during anaesthesia: regurgitation, vomiting, and aspiration. Quality & safety in health care. 2005;14(3): e4.
8White RJ, Bali S, Bark H. Xylazine and ketamine anaesthesia in the dromedary camel under field conditions. Vet Rec. 1987 Jan 31;120(5):110-3.
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