Dehydration in Camels During Capture and Chemical Immobilization
Inhabiting the desert areas of western Asia and central and east Asia, camels are even-toed ungulates comprised of two main species: the dromedary camel (Camelus dromedaries, or the Arabian camel) and the Bactrian camel (Camelus bactrianus). The Bactrian camel has two humps and is native to east Asia, while the dromedary camel has a single hump and lives in the warmer areas of western Asia and Arabia.
The ancestors of modern camels evolved in North America during the Palaeogene period and later spread to Asia, subsequently becoming extinct in North America.1 Most of the estimated 14 million dromedary camels alive today have been domesticated. There are approximately 1,000 wild Bactrian camels in China and Mongolia, with several million more domesticated Bactrian camels in east Asia.
Camels were first domesticated 3,000 years ago.2 They were used extensively as pack animals on the Silk Road, the network of routes used by traders between Europe and Asia for more than 1,500 years because they could carry more weight than horses or donkeys, needed less water and were able to thrive on tough desert plants. Today, camels are still used for milk, meat and as pack animals.
Adult camels stand about 6 feet at the shoulder and approximately 7 feet at the hump. They can run up to 40 miles per hour at a sprint, and sustain speeds of up to 25 miles per hour.3 Camels have an upper lip that is split in two with each part being independently mobile. This allows them to forage in harsh conditions. They also have a three-chambered rather than a four-chambered digestive tract.1,3 Camel humps store up to 80 pounds of fat, which camels break down into water and energy when food is scarce.2,3
Camels and Chemical Immobilization
The chemical immobilization of camels is sometimes required for medical examination, blood sample collection, and animal identification. Research in this area itself 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
There are a number of common stressors attendant to the chemical immobilization of 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—stimuli or agents inducing stress—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 in immobilization events. The physical stress of capture and/or attempts to escape during capture on the part of an animal certainly 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.
The effects of acute stress during capture can include 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, acidosis; in severe cases, this can lead to neurological/myocardial dysfunction, multi-organ failure, capture myopathy and death.5,6
While most camels have been acclimatized to human handling and tend to be far less prone to capture stressors, there are still camels in the wild. Additionally, dromedary camels were introduced into Australia in the 1840's to assist in the exploration of the inland continent. Today, there are over one million feral camels in the rangeland ecosystems of Australia.7 These animals are causing significant damage to the natural environment as well as having a negative social, cultural and economic impact across their extensive range.
By way of monitoring and management, radio-collared camels are now being used to enhance population control programs. This involves immobilizing individual camels, attaching telemetry collars, and releasing the collared animal to re-join its herd. The collared individuals are subsequently tracked via GPS and communications satellites.7
Dehydration in Camels
All animals require water to ensure their bodies are working properly. It is so important that essentially all bodily functions require it 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.8 The camel’s maintenance of fluid, electrolyte and circulatory homeostasis when dehydrated is believed to be dependent upon hormonal factors. Yet, despite their unique evolutionary adaptations, camels can ultimately suffer the ill effects of dehydration like other animals.
While dehydration may seem like a minor concern compared to some surgical complications, inasmuch as it can lead directly to cardiac arrest, dehydration is potentially quite dangerous. Electrolytes are minerals that naturally occur in all animals, 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 An animal’s natural activities—breathing, urinating, and defecating, as well as simple evaporation—can all cause it 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 Camels
The dynamics of dehydration are based in the distribution of fluid and water in the body. Total body water (TBW) comprises approximately 60% of an animal’s body weight. Approximately 67% of TBW is found inside the body’s cells; this is referred to as intracellular fluid (ICF). The remaining 33% of TBW is the extracellular fluid (ECF), which comprises:
- Interstitial fluid, which 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, which comprises synovial joint fluid, cerebrospinal fluid, bile, and the fluid in the linings of the peritoneal cavity, pericardium, and pleural space (~2% of TBW)5
A simple 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 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. In both human and veterinary practices, 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 Camels
Monitoring core body temperature is essential in camel anesthesia,6,9 and intubation has been widely recommended for any anesthetized camel that needs to be transported or anesthetized for greater than twenty minutes.9 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 is very common in veterinary medicine and allows practitioners to restore intravascular volume, correct dehydration, and administer IV medications quickly.6 While perioperative fluid therapy under many field conditions may be impractical, fluids should always be available in the case of dehydration when chemically immobilizing 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).
8Ali 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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