Aspiration in Bactrian Camels During Capture and Chemical Immobilization
The Bactrian camel (Camelus bactrianus) inhabits parts of central Asia and western China. The main characteristic that sets Bactrian camels apart from dromedary camels (Camelus dromedarius) is that they have two humps on their backs, whereas dromedary camels have only one.1 Like dromedary camels, Bactrian camels are large animals with an average height of 6-1/2 feet high at the hump. Males weigh 900 to 1,400 pounds; females are about 10% smaller and lighter.
Camels were used almost exclusively as pack animals on the Silk Road, the network of routes used by traders between Europe and Asia for centuries. This was 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 coat of the Bactrian camel is usually a dark brown or dirty gray color. Bactrian camels also have longer hair than their Western cousins; the coat is thicker and heavier on the head, neck, humps, forelegs, and tail regions. Seasonal temperature changes in their ranges require Bactrian camels to shed their heavy coat when the seasons change.1
Bactrian camels have a double row of long eyelashes that block harsh winds that can blow sand and dust into the camels' eyes. Their ears are also lined with hair and their top lip is divided to aid in foraging in harsh conditions. Their nostrils can be closed to shield against dust and sand.
Wild Bactrian camels live in herds of about 6-20, although they can occasionally aggregate in groups of up to 30 individuals. Herds typically consist of one alpha adult male leading adult females and their calves. Both camel species are polygynous, wherein the dominant male will mate with any of the females in the herd. The Bactrian camel's breeding season takes place in March and April. Calves are born weighing about 37 kg and are fully mobile within the first 24 hours. Calves in the wild are typically weaned within the first two years.1
Bactrian camels are not territorial; sometimes, multiple herds will cross paths and form a larger herd which can reach up to 500 individuals. Herds spend the majority of their days migrating and grazing. During the winter months, Bactrian camels migrate to the Gobi desert steppe, returning to the desert when the snow melts in the spring.
What is Aspiration?
Aspiration describes when a foreign substance enters a human or animal’s airway or lungs. This might include 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),3 but in some instances it can be brought on during or after chemical immobilization 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 of 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 aspirated into the lungs. This can represent a much larger volume of food and/or fluids being aspirated, and can lead to serious complications. While postoperative nausea and vomiting (PONV) is common in humans and other mammals,4 intraoperative aspiration (aspiration during a surgical procedure), is very dangerous and can prove fatal.5
Bactrian 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. Additionally, most camels alive today are domesticated or have come from domesticated stock. As such, camels tend to be more acclimatized to human handling, which tends to lessen the impact of capture stress.
The chemical immobilization of Bactrian camels with chemical agents is a method of rendering them tractable while using minimal restraint. Here, the research or management objectives are usually to measure or weigh an animal, for the 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.6,7
Given the extent of their domestication, 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
Anesthetic Aspiration in Bactrian Camels
When foreign substances such as food, drink, or stomach contents make their way into a camel’s lungs, they can significantly damage the lung tissues, resulting in acid-associated pneumonitis or other bacterial infections. Prior to formulated drugs (e.g., combinations of α2-agonists such as medetomidine, detomidine, xylazine and their reversal agents) coming into use in recent years, opioids were the mainstay of wildlife anesthesia.7 Like 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, this can be impractical if not 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.
Preventing and Managing Aspiration in Bactrian Camels
In preparing Bactrian 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 all camels be orotracheally intubated for procedures lasting more than 20 minutes.9
In order to prevent anesthetic aspiration, the 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 Bactrian camel aspirates during a procedure, the first step in managing the situation is the 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 will be necessary, 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 needed.5,8
4Shaikh, 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.
About NexGen Pharmaceuticals
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.
Our pharmacists are also encouraged to develop strong working relationships with our veterinarians in order to better care for veterinary patients. Such relationships foster an ever-increasing knowledge base upon which pharmacists and veterinarians can draw, making both significantly more effective in their professional roles.
Disclaimer
The information contained in this blog post is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the medications shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular medication. You should consult your veterinarian about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the medications to diagnose, cure or prevent disease. Medications compounded by NexGen Pharmaceuticals are prepared at the direction of a veterinarian. NexGen Pharmaceuticals compounded veterinary preparations are not intended for use in food and food-producing animals.
NexGen Pharmaceuticals, LLC does not recommend, endorse or make any representation about the efficacy, appropriateness or suitability of any specific dosing, products, procedures, treatments, services, opinions, veterinary care providers or other information that may be contained in this blog post. NEXGEN PHARMACEUTICALS, LLC IS NOT RESPONSIBLE NOR LIABLE FOR ANY ADVICE, COURSE OF TREATMENT, DIAGNOSIS OR ANY OTHER INFORMATION, SERVICES OR PRODUCTS THAT YOU OBTAIN THROUGH THIS BLOG POST.