Vomiting in Bactrian Camels During Capture and Chemical Immobilization

The Bactrian camel (Camelus bactrianus) is native to the steppes of Central Asia. They are migratory, with habitats that range from rocky foothills to deserts. These are areas with extremely harsh conditions where vegetation tends to be sparse and water sources are limited. Often, large groups of Bactrian camels will congregate near rivers after rain or at the foot of the mountains, where water can be obtained from springs in the summer months, and from melting snows during the winter.¹ Temperatures in the Bactrian camel’s natural environment range from as low as −40 °C in winter to 40 °C in summer.

The Bactrian camel has a long, wooly coat which varies in color from dark brown to beige. They have a mane and beard of long hair on the neck and throat. This camel differs most notably from the dromedary camel (Camelus dromedaries, which is found in the Middle East and western Asia) in that they have two humps on their backs instead of one. The two humps on the back are composed of fat, which the camels use to store energy when food is scarce.

Like the dromedary camel, Bactrian camels have a split upper lip, which allows them to forage short plants more effectively. They have long eyelashes and nostrils that they can close, which help to keep out dust from sandstorms which occur in their natural range.²

Bactrian camels are diurnal; they sleep in the open at night and forage for food during the day. They are technically omnivores, but are primarily herbivorous. They can go without water for months at a time, but when water is available, they can drink up to 30 gallons at a time. When well-fed, the camel’s humps are erect, and as food sources decline, the humps shrink and lean over. Bactrian camels can run as fast as 40 mph, but they rarely move at this pace.

Bactrian camels are polygynous animals, with one male mating with multiple females. During mating time, the males can be violent and may bite, spit or sit on other males.³ Gestation lasts from 12 to 13 months, after which one or two calves will be born. The calves are born precocial and are able to stand and run shortly after birth.³ The young are nursed for about 18 months and stay with their mother for 3 to 5 years.

Vomiting and Anesthetic Aspiration

Vomiting is a common post-sedation and post-anesthesia complication in both domestic and exotic animals. It is actually not uncommon for both humans and animals to vomit once or twice after a surgical procedure. If the vomiting continues however, it can be a sign of an emerging complication. A far more serious complication involves vomiting that occurs during a surgical procedure, since this can pose serious risks due to anesthetic aspiration.

Anesthetic aspiration can occur when a camel vomits food from its stomach during a surgical procedure which subsequently makes its way into the lungs. This can lead to aspiration pneumonia, a potentially fatal complication.⁴ Anesthesia-related aspiration is defined as the entry of liquid or solid material into the trachea and lungs. This occurs when patients without sufficient laryngeal protective reflexes (as a result of sedation or anesthetic agents) regurgitate gastric contents. “Pulmonary syndromes of differing severity can result, ranging from mild symptoms such as hypoxia to complete respiratory failure and acute respiratory distress syndrome (ARDS).”⁴ In extreme circumstances, cardiopulmonary collapse and death can occur. The related pulmonary syndromes can include acid-associated pneumonitis, particle-associated aspiration or bacterial infection. Which of these develops will depend upon the composition and volume of the aspirate.

Acute intraoperative aspiration (aspiration during a surgical procedure) is a potentially fatal complication with significant associated morbidity. Camels undergoing thoracic surgery are at increased risk for anesthesia-related aspiration due to the predisposing conditions associated with this complication. Awareness of the risk factors, predisposing conditions, precautions to decrease risk and immediate management options by the veterinarian are imperative to reducing risk and optimizing outcomes associated with acute intraoperative aspiration.⁴

Bactrian Camels and Chemical Immobilization

The veterinary care of both non-domestic and highly-domesticated hoofstock such as Bactrian camels has become commonplace due to the integration of veterinary medicine in wildlife management programs, zoological collections, exotic animal ranching expansions and the private collection of wildlife species.⁵ As a result, research and wildlife veterinarians are required to amass the requisite knowledge associated with safely anesthetizing and handling these animals.

The sedation and anesthesia of Bactrian camels requires extensive knowledge of the pharmacology of the drugs being used. A major challenge—and one which impacts potential complications such as anesthetic aspiration—is correlating the available pharmaceutical tools with the environment and conditions, as well as the procedures and events preceding, during, and following the anesthetic event.⁶ For example, an anesthesia protocol that’s practical in a fenced captive environment may not be appropriate in a free-ranging environment or large enclosure.

Today, the quality of sedation, anesthesia and analgesia achievable in Bactrian camels and other wildlife species has been made possible through the availability of new, receptor-specific and highly potent agonist-reversible pharmaceuticals and the improved knowledge of CNS receptors.

Due to their high level of domestication, camelids (camels, llamas and alpacas) are usually agreeable when it comes to handling, thus physical restraint and local anesthetic techniques are frequently used to provide immobility and analgesia. General anesthesia techniques are similar to those for ruminants and horses.^7,8 Regurgitation of compartment one (C1) of the stomach contents and postoperative nasal congestion and associated respiratory distress postextubation are potential hazards associated with anesthesia.⁸

The monitoring of 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 Anesthetic Vomiting in Bactrian Camels

Guidelines for the preparation of Bactrian camels for anesthesia and surgery include decreasing the size and pressure in C1 before anesthesia, withholding food for 12 to 18 hours in adults 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. Additionally, 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.⁸

To prevent anesthetic aspiration, histamine (H2) antagonists such as cimetidine, famotidine, nizatidine, and ranitidine and proton pump inhibitors (PPIs) such as dexlansoprazole, esomeprazole, lansoprazole, omeprazole, pantoprazole, and rabeprazole have been shown to be effective in increasing the pH and reduce the volume of gastric contents.⁴Additionally, prokinetics (e.g., domperidone, metoclopramide, erythromycin and renzapride) promote gastric emptying and are believed to reduce the risk of aspiration.⁶

The first step mitigating intraoperative aspiration is the recognition of gastric content in the oropharynx or the airways.⁴The camel should be immediately 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. The airway should be secured as rapidly as possible to prevent further contamination and to facilitate airway clearance.⁶ Flexible bronchoscopy is an important adjunct to orotracheal and endotracheal suctioning, and having a flexible bronchoscope at the ready if possible is a sound prophylactic measure. If particulate matter is present in the airway, rigid bronchoscopy may be required.^4-7