Aspiration in Camels During Capture and Chemical Immobilization
Adapted to the harsh conditions of the Middle East and Central Asia, camels have been so widely used as pack animals in these regions over the past 3,500 years that the majority of camels have been domesticated.1 There are three recognized species of camel: the dromedary camel (Camelus dromedaries, also known as the Arabian camel), the Bactrian camel (Camelus bactrianus) and the wild Bactrian camel (C. ferus). Wild Bactrian camels are leaner in build than their domesticated counterparts, with smaller humps and less hair.
Camels were used almost exclusively as pack animals on the Silk Road, the network of routes used by traders between Europe and Asia for more than 1,500 years. This was largely because they could carry more weight than horses or donkeys, needed less water and were able to thrive on tough desert plants. Arabian camels were used primarily on western Silk Road routes, while Bactrian camels were used in the colder areas of Central Asia, Mongolia and China.2
The dromedary camel has one back hump, while the domesticated Bactrian and wild Bactrian camels have two humps. All camel species are approximately 10 feet long and 6-1/2 feet high at the hump. Males weigh 900 to 1,400 pounds; females are about 10% smaller and lighter. Their color is light brown to medium gray.2 All camels have heavy eyelashes to protect their eyes from blowing sand, and their nostrils can be squeezed shut.
All camels are seasonal breeders, with females coming into heat during the breeding season. This normally occurs during the winter months, from November to March.1
Camels are diurnal and spend much of their days eating. Each half of their split upper lips move independently, so camels can forage for short grass very near to the ground. They can go a week or more without water, and a camel can last for several months without food. Their humps store up to 80 pounds of fat, which camels break down into water and energy when food is scarce.2,3
Aspiration is 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 (referred to as dysphagia), but in some instances 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. In the case of anesthetic aspiration, the 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. While postoperative nausea and vomiting (PONV) is common in humans and other mammals,4intraoperative aspiration (aspiration during a surgical procedure), is very dangerous and can prove fatal.5
Camels and Chemical Immobilization
At the beginning of the last century, the primary method used for the capture of many large wild animals was to chase them to the point of near-exhaustion—a method that was quite labor-intensive, impractical and fairly inhumane.6 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.
The field immobilization of wild 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.6,7 These requirements have resulted in the development of safe methods in chemical immobilization.
Given the extent of their domestication, despite their size, camels 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.8,9 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 camel anesthesia.9
Chemical Immobilization in Practice
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 wild mammals 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 (in the case of field research) 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 Camels
When foreign substances such as food, drink, or stomach contents make their way into the lungs, they can significantly damage the 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.7 As with other mammals, problems encountered with certain opioids (such as etorphine or carfentanil, which have been widely used in wildlife chemical immobilization) in camels 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 camel 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 camel anesthesia in wildlife and captive care.5
Preventing and Managing Aspiration in Camels
In preparing camels 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 camels younger than one month of age rarely regurgitate during anesthesia. It is also recommended that camels be orotracheally intubated for procedures lasting more than 20 minutes.9
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.4
In the event that a camel aspirates during a procedure, the first step in managing the situation is the immediate recognition of gastric content in the oropharynx or the airways.2 The camel 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 is an important adjunct to orotracheal and endotracheal suctioning, but 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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