Vomiting in Dromedary Camels During Capture and Chemical Immobilization
Having been widely domesticated beginning approximately 3,500 years ago, the dromedary camel (Camelus dromedarius) has not occurred naturally in the wild for over 2,000 years.1 Today, domestic dromedary camels (also called Arabian camels) are found in the Middle East, northern India and Africa. There is also a population of feral dromedary camels in Australia, where they were introduced nearly 200 years ago.
There are few wild species that are as iconic as the camel. There are three recognized species of camel—these are the dromedary camel, the Bactrian camel (C. bactrianus) and the wild Bactrian camel (C. ferus). The Bactrian camel has two humps, while the dromedary camel has a single hump. Approximately 90% of the world's camels are dromedary camels.
As a rule, dromedary camels are diurnal and generally shy, although they are very social within groups and herds. In family groups, the male is dominant and directs the family from the rear, with females taking turns leading. They are herbivores with a diet that consists of foliage, grasses, and desert vegetation such as thorny plants. Their thick lips allow them to eat things that other animals can't, and a split upper lip helps them to be very effective in this regard.
Dromedary camels are polygamous, with a breeding season that runs from November through March. Gestation lasts from 12 to 13 months, with one calf, and occasionally twins being born. Calves can usually stand within 8 hours and are fully mobile within 24 hours.2,3 They remain with the herd until they are old enough to become independent, which is usually within 1 to 2 years.
All of the recognized camel species are approximately 10 feet long and 7 feet high. Males weigh from 900 to 1,400 pounds; females are about 10% smaller and lighter. Camels can go a week or more without water, and they 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 not available.3 The humps give camels their noted ability to travel long distances in the desert without food. When camels do drink water, they can consume up to 30 gallons in one sitting.
Dromedary camels were first introduced into Australia in the 1840's to assist in the exploration of the inland continent. As a result, there are currently over one million feral camels in the rangeland ecosystems of Australia. Unfortunately, these animals are causing significant damage to the natural environment as well as having a negative social, cultural and economic impact across their range. As a control method, radio-collared camels are being used as a part of comprehensive population control programs, which involves immobilizing individual camels.4 This routinely-performed procedure carries the risk of inducing capture-related complications.
Vomiting as a Complication
Vomiting is a very common post-sedation and post-anesthesia complication in both domestic and exotic animals. In fact, it is not unusual for both humans and animals to vomit once or twice after a surgical procedure. However, if the vomiting continues, it can be a sign of an emerging complication. A far more serious complication involves vomiting that occurs during a procedure, since this can pose grave risks due to anesthetic aspiration.
Anesthetic aspiration involves a camel vomiting food from its stomach during a surgical procedure, which subsequently infiltrates into the lungs. This can lead to a serious condition known as aspiration pneumonia. Respiratory complications such as anesthesia-related aspiration and pneumonia can be fatal.4
Anesthesia-related aspiration is the entry of liquid or solid material into the trachea and lungs. “Pulmonary syndromes of differing severity can result, ranging from mild symptoms such as hypoxia to complete respiratory failure and acute respiratory distress syndrome (ARDS).”5 In extreme circumstances, cardiopulmonary collapse and death can occur. The related pulmonary syndromes can include acid-associated pneumonitis, particle-associated aspiration (airway obstruction) or bacterial infection. Which of these develops depends 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. Dromedary camels undergoing thoracic surgery are at increased risk for anesthesia-related aspiration, largely 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 essential in reducing risk and optimizing outcomes associated with this complication.4
Preparation and Precautions
The veterinary care of domestic and non-domestic hoofstock has become routine due to the integration of veterinary medicine in wildlife management programs and zoological collections.5 As a result, research and wildlife veterinarians are required to amass a great deal of knowledge associated with safely anesthetizing and handling these animals.
The sedation and anesthesia of dromedary camels requires the knowledge the pharmacology of the drugs being used, as well as the wide variation in dose response across this species. One challenge 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.7 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 dromedary camels and other wildlife species has been made possible through the availability of new, receptor-specific and highly potent agonist-reversible pharmaceuticalsand the improved knowledge of CNS receptors.
Dromedary Camels and Chemical Immobilization
Due to their widespread domestication, despite their size, camelids (camels, llamas and alpacas) tend to be agreeable when it comes to handling, thus physical restraint and local anesthetic techniques are often used to provide immobility and analgesia. General anesthesia techniques are similar to those for ruminants and horses.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 the anesthesia of dromedary camels. In most cases, recovery from anesthesia is generally uneventful.9
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 Anesthetic Vomiting in Dromedary Camels
Guidelines for the preparation of dromedary 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. 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
In preventing 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 helpful in increasing the pH and reduce the volume of gastric contents.4 Prokinetics (e.g., domperidone, metoclopramide, erythromycin and renzapride) promote gastric emptying and reduce the risk of aspiration.6
The immediate recognition of gastric content in the oropharynx or the airways is the first step in successful management of an intraoperative aspiration.4 The 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 visible in the airway, rigid bronchoscopy may be indicated.4-7
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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