Cardiac Arrest in Bactrian Camels During Capture and Chemical Immobilization
The Bactrian camel (Camelus bactrianus) is native to central Asia. While domesticated Bactrian camels number in the millions, there are said to be less than 1,000 of these animals left in their native range in Mongolia. Bactrian camels can reach seven feet in height and weigh up to 1,500 pounds.1 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.1,2
Overall, camels are one of the most well-recognized and iconic species, but what distinguishes the Bactrian camel from its western cousin the dromedary camel (Camelus dromedarius) is that the Bactrian camel has two humps, while the dromedary (or Arabian) camel has only one.
Contrary to popular belief, a camel’s humps don’t store water; they actually store fat, which the camel uses as an energy source when food is scarce. Bactrian camels are grazing animals that subsist on grasses, leaves, and shrubs, but they can also process thorns, salty plants and dry vegetation that are indigestible to other herbivores. This adaptation enables the Bactrian camel to survive in areas of sparse vegetation. They can go for extended periods of time without drinking water, but when they do drink, they can consume up to 30 gallons in one sitting.2
The camel’s adaptations to life in the desert are well-known. The Bactrian camel’s long eyelashes and elongated nostrils (which they can close) protect them from blowing dust and sand. Their split, partially prehensile lips allow them to forage vegetation that would be inaccessible to other large herbivores. They have specialized blood cells which allow them to survive periods of dehydration,3 and their thick coats change with the seasons, being shed during the summer months.
In the wild, Bactrian camels form herds of up to 30 individuals led by a single breeding male. Males that do not find mates often gather in single-sex bachelor herds. Pregnancy in camels lasts for 11 months, with calves being born in March and April. Juvenile camels mature after about five years, and individuals typically live up to five decades.
Camel Chemical Immobilization and Cardiac Arrest
Veterinarians and wildlife management personnel are regularly called upon to chemically immobilize Bactrian camels for medical treatment, research and other management functions. The varying protocols and dosage variations for immobilizing drugs present an increased 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.4 Unfortunately, the mechanism of opioid action increases the risk for respiratory and cardiac depression and arrest. Monitoring core body temperature is essential in camel anesthesia,4,5 and it is recommended that camels be orotracheally intubated for procedures lasting more than 20 minutes.6
Cardiac arrest, or cardiopulmonary arrest (CPA) is described by a complete failure of the respiratory and circulatory systems. The resulting lack of oxygen transport can quickly cause 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 Therefore, prompt cardiopulmonary resuscitation is essential.
Both Bactrian and dromedary camels have been highly domesticated over the last 3,500 years; thus, the effects of capture stress tend to be less than they would be in wild hoofstock species. That said, capture and/or chemical immobilization can still result in CPA events 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)6 or a variety of comorbidities. Early signs of an impending CPA event may 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; fixed, dilated pupils or changes in mucous membrane color.
Responding to Cardiac Arrest in Bactrian Camels
Cardiopulmonary cerebral resuscitation in Bactrian camels involves three stages:
- Basic life support (BLS),
- Advanced life support (ALS)
- Post resuscitation care
Stage 1 involves establishing a clear airway, providing assisted ventilation, and performing chest compressions. If a camel’s pulse becomes absent or weak, all administration of immobilizing drugs must be ceased and external cardiac massage should be initiated. Veterinary patients can usually be easily ventilated with a bag-valve mask,6,8 the caveat being that this may not be available under field conditions.
In Stage 2, the veterinarian can establish venous access 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.6 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. If there is still no response, the epinephrine and calcium chloride may be re-administered with 10-20 mEq IV or IC sodium bicarbonate.5-7
Camels that are restored to a perfusing cardiac rhythm may experience rearrest. This is particularly likely if the original cause of the CPA event has not been identified. Stage 3 involves providing resuscitated patients with cardiovascular and ventilatory support during the period following CPA. Inducing mild hypothermia after resuscitation from CPA decreases cerebral oxygen demand and has been shown to improve outcomes.8
5Pablo L.S. Current concepts in cardiopulmonary resuscitation. World Small Anim Vet Assoc World Congr Proc:2003.
7Ball, L. Camel Anesthesia. Wiley Online Library, 25 July 2014.
8Kreeger T., Arnemo, J., Raath, J. Handbook of Wildlife Chemical Immobilization, International Edition, Wildlife Pharmaceuticals, Inc., Fort Collins, CO. (2002).
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.
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