Cardiac Arrest in Dromedary Camels During Capture and Chemical Immobilization
Dromedary camels (Camelus dromedaries, also called Arabian camels) are found in the Middle East, northern India and northern Africa. There is also a population of feral dromedary camels in Australia, where they were introduced nearly 200 years ago. Having been widely domesticated beginning approximately 3,500 years ago, the dromedary camel (Camelus dromedarius) has not occurred in the wild for over 2,000 years.1
There are three recognized species of camel—the dromedary camel, the Bactrian camel (C. bactrianus) and the wild Bactrian camel (C. ferus). The Bactrian and wild Bactrian camels have two humps, whereas the dromedary camel has a single hump. All camels are camelids, which includes camels, alpacas and llamas. They are members of the biological family Camelidae, and the only family in the suborder Tylopoda.1
Camels are ruminants, but they differ from other ruminants in a few significant ways: Camels have a three-chambered digestive tract rather than a four-chambered one. Their upper lip is split in two with each part being separately mobile, and they have an isolated incisor in the upper jaw. Their oval-shaped red blood cells help to facilitate blood flow when the animal is dehydrated. The camel’s red blood cells are also able to withstand high osmotic variation without rupturing when these animals drink large amounts of water (up to 30 gallons in one sitting).2,3
Dromedary camels 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 the split upper lip helps them to be very effective in this regard. Their humps store up to 80 pounds of fat, which camels break down into water and energy when food is not available.2,3 The humps give camels their noted ability to travel long distances in the desert without food. Camels can go a week or more without water, and they can last for several months without food.
All of the recognized camel species grow to approximately seven feet in height. Males weigh from 900 to 1,400 pounds; females are about 10% smaller and lighter. 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.
Chemical Immobilization of Dromedary Camels
Veterinarians and wildlife management personnel are regularly called upon to chemically immobilize dromedary camels for medical treatment, research and the like. Dromedary camels were introduced into Australia in the 1840's to assist in the exploration of inland Australia. Today, there are over one million feral camels in the rangeland ecosystems of Australia.4 Unfortunately, these animals are causing significant damage to the natural environment. Radio-collared camels are currently being used in Australia to enhance population control programs. This involves immobilizing individual camels, attaching telemetry collars, and releasing collared animals to re-join their herds.4 These procedures carry the risk of inducing a wide range of complications in the target animals.
The different species protocols and dosage variations for immobilizing drugs also increase the risk of complications during anesthetic events. 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 Monitoring core body temperature is essential in camel anesthesia,5,6 and it is recommended that any camel being sedated or anesthetized be orotracheally intubated for procedures lasting more than 20 minutes.7
Chemical Immobilization and Cardiopulmonary Arrest
Cardiac arrest, or cardiopulmonary arrest (CPA) is a sudden and complete failure of a camel’s respiratory and circulatory systems. The resulting lack of oxygen transport can quickly cause systemic cellular death from oxygen depletion.5 If left untreated, cerebral hypoxia can result in death within four to six minutes of a CPA event.6 In these cases, prompt cardiopulmonary resuscitation is imperative.
Capture and/or chemical immobilization can result in CPA events in dromedary camels. In some instances, the stress of capture (depending upon the method thereof) can significantly increase the likelihood of cardiac arrest in these animals. While under anesthesia, common causes of CPA can include vagal stimulation, unstable cardiac arrhythmias, severe electrolyte disturbances, exacerbated cardiorespiratory disorders (e.g., congestive heart failure, hypoxia)5 or a variety of comorbidities. Signs of an impending CPA event can include dramatic changes in breathing effort, rate, or rhythm, significant hypotension, absence of a pulse, irregular or inaudible heart sounds, changes in the heart rate or rhythm; changes in mucous membrane color and fixed, dilated pupils.
Cardiopulmonary Arrest in Dromedary Camels
Cardiopulmonary resuscitation in dromedary camels involves three stages:
- Basic life support (BLS),
- Advanced life support (ALS)
- Post resuscitation care
The first stage involves establishing an open airway, providing assisted ventilation, and performing chest compressions. If the camel’s pulse becomes absent or weak, all administration of immobilizing drugs must be ceased and external cardiac massage should be initiated. In most cases, veterinary patients can be ventilated with a bag-valve mask,5,9 although this may not be available under field conditions.
Venous access can be established by using such methods as intraosseus catheter placement and venous cutdown, in which a small opening is created in a vein to allow passage of a needle or cannula.5 Epinephrine at 0.2 mg/kg (concentrated at 1/10,000) should be given IV or intracardially (IC) while cardiac massage continues. If the camel fails to respond, 0.1 ml/kg IV or IC calcium chloride may be given. In the absence of a response, the epinephrine and calcium chloride may be re-administered with 10-20 mEq IV or IC sodium bicarbonate.6-8
Dromedary camels that are restored to a perfusing cardiac rhythm may experience rearrest, especially if the original cause of the CPA event has not been identified. Therefore, resuscitated patients usually should have cardiovascular and ventilatory support during the period following CPA.9
6Pablo L.S. Current concepts in cardiopulmonary resuscitation. World Small Anim Vet Assoc World Congr Proc:2003.
8Ball, L. Camel Anesthesia. Wiley Online Library, 25 July 2014.
9Kreeger T., Arnemo, J., Raath, J. Handbook of Wildlife Chemical Immobilization, International Edition, Wildlife Pharmaceuticals, Inc., Fort Collins, CO. (2002).
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