Aspiration in Alpacas During Capture and Chemical Immobilization
While lay persons sometimes refer to the alpaca (Lama pacos or Vicugna pacos) as “a type of llama,” these animals are actually a discrete species that was probably descended from the vicuña several thousand years ago. Alpacas are distinguished from llamas by their smaller size; in fact, they are the smallest of the domesticated camelid species (the group which includes dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas, and guanacos).1 The native range of the alpaca includes the central and southern Andes from Peru to Argentina.
Alpacas have a face that resembles a camel’s, a long neck, tapering ears and an upper lip with a deep cleft. With the exception of the face and legs, the alpaca’s entire body is covered with long, thick, soft wool. Alpaca fiber is lustrous, soft and silky, and is suitable for commercial use. Alpaca wool is used for making a wide range of knitted and woven items.
Alpacas are herbivores, grazing on grass and eating weeds, shrubs and trees. They have special stomach secretions that help them absorb 50% more nutrients than sheep, allowing them to survive where the food quality is poor.2 In the wild, these animals, who live in herds, are prey to pumas, leopards, and other carnivores. Their long necks however, help them spot predators among the rocks of the mountain slopes.
Alpacas are easily domesticated, which has been borne out by the fact nearly all of these animals have been domesticated. Their disposition is generally friendly and gentle. In the Andes, the mating period for alpacas runs from August through September. Their babies are called crias, to which they give birth every 11 months. The crias typically weigh 15-20 pounds at birth. Adult alpaca reach about 3 feet in height and 150 pounds in weight.2 Alpacas live 15 to 25 years.
Alpaca wool fibers are highly durable and hollow, which gives them the ability to insulate very well, and to absorb moisture. As a result, alpaca farming has become a worldwide cottage industry. Today, there are over 50,000 alpacas in dozens of farms across the US alone. Alpacas have been domesticated for thousands of years; it is thought even prior to the period of the Incas, who raised and bred alpacas for wool clothing.
What is Aspiration?
The utility and popularity of alpacas, along with the needs of zoo, wildlife management and research personnel, occasionally necessitate the chemical immobilization of these animals. This puts them at risk for complications that can arise from these events, including vomiting and aspiration. Camelids, like other ruminants, have certain special requirements for sedation and anesthesia (see below); attention to these can significantly mitigate the risk of these and other complications.
Aspiration occurs when a foreign substance enters the airway or lungs. This might be food, liquid, or other materials. Aspiration can give rise to serious health problems, such as pneumonia. It 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). It then progresses 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. It then moves into the trachea and into the lungs.
In cases dysphagia, small amounts of food or fluids may be inadvertently aspirated. When this occurs in the conscious animal, the aspirate may be 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
Alpacas and Chemical Immobilization
The field immobilization of animals with chemical agents is a method of rendering wild animals tractable while using minimal of restraint. Here, the research or wildlife management objectives are usually to measure or weigh the 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 for a variety of reasons.5,6
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. At the beginning of the last century however, the primary method used for the capture of larger wild animals was to chase them to the point of near-exhaustion—a method that was labor-intensive, impractical and inhumane.5
Given the extent of their domestication, despite their size, alpacas are often agreeable when it comes to handling, thus physical restraint and local anesthetic techniques are frequently used to provide immobility and analgesia. Anesthesia techniques are similar to those for ruminants and horses.7,8 Regurgitation of compartment one (C1) of the stomach contents, similar to ruminants, and postoperative nasal congestion and associated respiratory distress postextubation are potential hazards associated with alpaca anesthesia.8
The utilization of basic veterinary knowledge can make a substantial contribution to animal safety during capture and chemical immobilization. Teams that are qualified to handle alpacas should evidence the appropriate expertise in wildlife anesthesia and should include an attending veterinarian when appropriate. A successful chemical restraint exercise is not complete until the subject is fully recovered and back in its environment.
The application of appropriate pharmacological principles with an emphasis on drug reversibility will minimize the chances that the animal will be at a competitive disadvantage or inordinately disoriented following its release. Further, residual sedation and renarcotization should be avoided in the field unless absolutely necessary.6,7
Anesthetic Aspiration in Alpacas
When foreign substances such as food, drink, or stomach contents make their way into the 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.6 As with other mammals, problems encountered with certain opioids (such as etorphine or carfentanil) in alpacas are known to include vomiting or passive regurgitation that can lead to fatal aspiration pneumonia.
Periprocedural fasting (fasting prior to an anesthetic event) has historically been recommended by clinicians because of the suspected risk of aspiration. Unfortunately, periprocedural fasting is very often impractical or impossible under field conditions. Additionally, much of the data on anesthetic aspiration relates to humans receiving general anesthesia, however, other mammals have been known to aspirate during procedures while under sedation and where no intubation or general anesthesia were employed.
Monitoring core body temperature is essential in alpaca anesthesia.6 Until the more recent use of formulated drugs (e.g., combinations of α2-agonists such as medetomidine, detomidine, xylazine and their reversal agents), opioids were the mainstay of alpaca anesthesia in wildlife and captive care.4
Preventing and Managing Aspiration in Alpacas
In preparing alpacas 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 alpacas younger than one month of age rarely regurgitate during anesthesia. It is also recommended that alpacas be orotracheally intubated for procedures lasting more than 20 minutes.8
For the prevention of anesthetic aspiration, the available literature also 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.2 Prokinetics (e.g., domperidone, metoclopramide, erythromycin and renzapride) promote gastric emptying and are also believed to reduce the risk of aspiration.3
In the event that an alpaca aspirates under sedation or anesthesia, the first order of business is the immediate recognition of gastric content in the oropharynx or the airways. The alpaca should be positioned with the head down and rotated laterally if possible. Orotracheal and endotracheal suctioning is indicated, either before or after orotracheal intubation, depending on whether regurgitation continues and if the airway is visible. 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 however, rigid bronchoscopy may be required.5,8
3 Shaikh, Safiya Imtiaz et al. Postoperative nausea and vomiting: A simple yet complex problem. Anesthesia, essays and researches vol. 10, 3 (2016).
4Nason, K. Acute Intraoperative Pulmonary Aspiration. Thoracic surgery clinics vol. 25,3 (2015): 301-7.
5Lance, W. Exotic Hoof Stock Anesthesia and Analgesia: Best Practices. In: Proceedings, NAVC Conference 2008, pp. 1914-15.
6Kluger M.T., et. al. Crisis management during anaesthesia: regurgitation, vomiting, and aspiration. Quality & safety in health care. 2005;14(3): e4.
7White 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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NexGen Pharmaceuticals is an industry-leading veterinary compounding pharmacy, offering sterile and non-sterile compounding services nationwide. Unlike other veterinary compounding pharmacies, NexGen focuses on drugs that are difficult to find or are no longer available due to manufacturer discontinuance or have yet to be offered commercially for veterinary applications, but which still serve a critical need for our customers. We also specialize in wildlife pharmaceuticals, including sedatives and their antagonists, offering many unique options to serve a wide array of zoo animal and wildlife immobilization and anesthesia requirements.
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