Dehydration in Bactrian Camels During Capture and Chemical Immobilization
Camelus bactrianus, or the Bactrian camel, inhabits parts of central Asia and western China. These animals are set apart from their more western-ranging relative, the dromedary camel (Camelus dromedarius), in that Bactrian camels have two humps on their backs, whereas dromedary camels have only one.1 Both Bactrian camels and dromedary camels are large animals with an average height of 7 feet. Males weigh 900 to 1,400 pounds; females are about 10% smaller and lighter. Bactrian camels are also noted for their shaggy coats, which they shed during the summer months.
Camels were widely employed as pack animals on the Silk Road, the network of Eurasian trade routes that was active from the second century BCE until the mid-15th century. This was because they could carry more weight than horses or donkeys, needed less water and were able to thrive on tough desert plants. Dromedary 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
Bactrian camels have a double row of long eyelashes that block the harsh winds which 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 also be closed to shield against dust and sand.
Like dromedary camels, most Bactrian camels alive today have been domesticated. There are however, herds of wild Bactrian camels in China and Mongolia. Wild Bactrian camels live in herds of about 6 to 20, although they sometimes gather in groups of up to 30 individuals. Herds typically consist of one alpha adult male leading adult females and their calves. Bactrian camels are not territorial; occasionally, 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.1
Both camel species are polygynous, meaning that the dominant male in a herd will mate with any of the females in the herd. The Bactrian camel's breeding season takes place in March and April. The calves are fully mobile within the first 24 hours after birth. Calves in the wild are typically weaned within the first two years.1,3
Bactrian Camels and Chemical Immobilization
The chemical immobilization of Bactrian camels is sometimes required for medical examination and/or treatment, identification and other management functions. Research in this area has revealed that the physiological and behavioral effects of capture are as important as the direct risks of injury or death of an animal.4,5
Despite their high level of domestication, there are a number of stressors involved in the chemical immobilization of Bactrian camels that can, in some cases, lead to complications during or after an anesthetic event. The overall health of an individual animal (which might be poor, and in some cases the very reason for its capture) is also a factor affecting the potential for complications during and after anesthesia.
In general, these stressors fall into four categories:
- Physiological: Heavy exercise, hemorrhage, hyperthermia, shock, pain, infection
- Physical: Trauma/surgery, intense heat/cold
- Chemical: Hypoxemia, acid-base imbalance, anesthetic drugs
- Emotional: Anxiety, fear6
Chemical immobilization agents are represented by the third category, although elements of the other three are often included when chemical immobilization takes place. The physical stress of capture and/or attempts to escape during capture on the part of an animal constitute physiological stress; surgical and even environmental conditions can bring about physical stress, and anxiety and fear are nearly always a component to some degree in a capture scenario.
Acute stress during capture can lead to spikes in adrenaline, cortisol levels, heart rate, blood pressure, respiration, metabolic rate, blood glucose, lactic acid and body temperature, while bringing about a decrease in pH and a redistribution of blood within the organs. The effects of capture and anesthesia can activate the fight-or-flight response, HPA-axis activation, hyperthermia, respiratory depression (hypoxemia), lactid acid build-up and acidosis. In severe cases, this can lead to neurological/myocardial dysfunction, multi-organ failure, capture myopathy and death.5,6
Dehydration in Bactrian Camels
All animals require water to ensure their bodies are working properly. This is so important that essentially all bodily functions require water to remain operative. If an animal loses more water and electrolytes than it is taking in, it will begin to dehydrate and its health will quickly deteriorate.
It is well-known that camels are able to survive without water for long periods compared to other species. The camel's physiological adaptation to the desert environment is due to adaptations that allow minimal use of evaporative cooling, low urinary output and an ability to extract water from undigested feed. Camels also have the ability to change their body temperature according to changes in the ambient temperature in order to save water.
The literature states that camels can tolerate a loss of water corresponding to 30% of their body weight when dehydrated, where other mammals can die from circulatory failure when their water loss exceeds 12% of their body weight.7 It is believed that the camel’s maintenance of fluid, electrolyte and circulatory homeostasis when dehydrated is dependent upon hormonal factors. Yet, despite their unique evolutionary adaptations, camels can still suffer the ill effects of dehydration like other animals.
Dehydration may seem like a minor concern compared to some surgical complications, but inasmuch as it can lead directly to cardiac arrest, it is potentially quite dangerous. Electrolytes, which are transported via the water in an animal’s body, are naturally-occurring minerals, and they are essential for proper health. Electrolytes are comprised of sodium, chloride, and potassium, and facilitate the movement of nutrients into cells, aid in muscle function, and help regulate nerve activities.5,6 Normal activities—such as breathing, urinating, and defecating, as well as simple evaporation—can all cause an animal to lose fluids. When an animal eats and drinks, the lost water and electrolytes are replaced. If the animal’s fluid intake becomes less than what they are losing, dehydration will occur.
Understanding Dehydration in Bactrian Camels
The dynamics of dehydration are based on the distribution of fluid and water in the body. Total body water (TBW) comprises approximately 60% of any animal’s body weight. An estimated 67% of TBW is found inside the body’s cells, and this is referred to as intracellular fluid (ICF). The remaining 33% of TBW is extracellular fluid (ECF), which comprises:
- Interstitial fluid; this bathes cells and tissues (~24% of TBW)
- Plasma (the liquid portion of blood), which constitutes most of intravascular volume (~8%–10% of TBW)
- Transcellular fluid (e.g., synovial joint fluid, cerebrospinal fluid, bile, and the fluid in the linings of the peritoneal cavity, pericardium, and pleural space: ~2% of TBW)5
An approximate formula for the distribution of fluids in the body is the 60:40:20 rule: 60% of an animal’s body weight is water, 40% of body weight is ICF, and 20% of body weight is ECF.5,6
Dehydration in Bactrian camels can be caused by hyperthermia, chronic vomiting or diarrhea, excessive urination or wound drainage. Due to the stressful nature of capture and chemical immobilization events, they have been known to bring about dehydration. To prevent dehydration in both human and veterinary surgeries, IV fluids are usually administered prophylactically, depending on the nature of the procedure. Veterinarians often provide fluid therapy to patients for many reasons, including correction of dehydration, expansion and support of intravascular volume, correction of electrolyte disturbances, and encouragement of appropriate redistribution of fluids that may be in the wrong compartment (e.g., peritoneal effusion).5
Treating Dehydration in Bactrian Camels
Monitoring core body temperature is essential in camel anesthesia,6,7 and intubation has been widely recommended for any anesthetized camel that needs to be transported or anesthetized for greater than twenty minutes.8 During anesthetic/immobilization events, hydration status can be assessed using various tests. One of the easiest to perform is a skin tent test to check the turgor (moisture level) of the skin. To do this, the skin over the thorax or lumbar region is pulled away from the back. In a well-hydrated animal, the skin immediately returns to its normal resting position. If the tent formed remains standing, it is a likely indication of dehydration. If there is evidence of dehydration in a camel during a procedure, all administration of immobilizing drugs must be immediately suspended. Fluid therapy should begin in the form of lactated Ringer’s solution or 0.9% saline, IV, SQ or IP.5
Perioperative IV fluid therapy will allow the veterinarian to restore intravascular volume, correct dehydration, and administer IV medications quickly.6 While the administration of perioperative fluid may be impractical under field conditions, fluids should always be available in the case of dehydration when chemically immobilizing Bactrian camels.
4Laricchiuta P, De Monte V, Campolo M, Grano F, Iarussi F, Crovace A, Staffieri F. Evaluation of a butorphanol, detomidine, and midazolam combination for immobilization of captive Nile lechwe camels (Kobus magaceros). J Wildl Dis. 2012 Jul;48(3):739-46.
5Brivio F, Grignolio S, Sica N, Cerise S, Bassano B (2015) Assessing the Impact of Capture on Wild Animals: The Case Study of Chemical Immobilisation on Alpine Ibex. PLoS ONE 10(6): e0130957.
6Kreeger T., Arnemo, J., Raath, J. Handbook of Wildlife Chemical Immobilization, International Edition, Wildlife Pharmaceuticals, Inc., Fort Collins, CO. (2002).
7Ali M.A., et. al. Responses to dehydration in the one-humped camel and effects of blocking the renin-angiotensin system. PLoS One. 2012;7(5):e37299. doi: 10.1371/journal.pone.0037299. Epub 2012 May 18. PMID: 22624009; PMCID: PMC3356281.
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