Shock in Bactrian Camels During Capture and Chemical Immobilization
Camels were first domesticated between 3,000 to 3,500 years ago.1 The two-humped or Bactrian camel (Camelus bactrianus) once served as a primary means of transport between East and West, especially during the time of the Silk Road, the network of routes used by traders between Europe and Asia for more than 1,500 years. This was chiefly because they could carry more weight than horses or donkeys, needed less water and were able to thrive on tough desert plants.
Named after an ancient region in Central Asia, the word “Bactrian” was first used to distinguish this camel from the dromedary or Arabian camel (Camelus dromedaries), which has only one hump.1 According to fossil evidence, the ancestors of modern camels evolved in North America during the Palaeogene period and later spread to Asia, later becoming extinct in North America.2
Bactrian camels are one of the few animals that are native to the Gobi desert in north central China, where fluctuating temperatures, scarce food and water and rugged terrain create a difficult environment. The rugged nature of this range makes it difficult for other animals to survive there. As a result, Bactrian camels have few natural competitors or predators. This, and their adaptations to the harsh habitat allow them to obtain sustenance and protect themselves from wind, heat, and cold.
Bactrian camels forage throughout the day, eating a wide variety of plants. It has been reported that they will also eat meat and fish when plat foods are unavailable.1,2 Their two humps store between 30 to 50 pounds of fat, which allows them to survive with little food for extended periods of time. Like dromedary camels, Bactrian camels have evolved specialized blood cells which store fluids to help keep them in good health even when they are dehydrated.3
Bactrian camels usually gather in small groups of up to six animals as they migrate through the desert in search of food and water. While most Bactrian camels are domesticated, wild Bactrian camels still exist. These live in herds of about 6-20, although they occasionally aggregate in groups of up to 30 individuals. Herds typically consist of one alpha male, adult females and their calves.
Bactrian Camels and Shock as a Complication
The management of and research into Bactrian camels often requires chemical immobilization. Unfortunately, this can lead to a variety of capture‐induced risks while these animals are chemically immobilized, including shock.
Shock is a serious condition that is brought on by a sudden drop in blood flow throughout an animal’s body. It can be the result of a variety of conditions or circumstances, including extreme physical stress, trauma, disease, heatstroke, blood loss, allergic reactions or severe infection. When a camel is in shock, its organs are not receiving an adequate amount of blood or oxygen. If untreated, this can lead to permanent organ damage or death.
The processes surrounding capture and chemical immobilization can include extreme physical stress sufficient to induce shock in animals. The degree of risk is dependent upon factors such as species, sex, age, overall health, environmental factors, length of immobilization, the degree of stress involved in the capture/immobilization event itself and the specific chemical agents involved in immobilizing the animal.
There are two types of shock, and these that are divided into three categories. The two types of shock are:
Primary shock (traumatic shock). This type of shock develops immediately after injury, trauma or extensive surgical wounds during operation and massive handling of internal abdominal organs. It is of nervous origin, transient in nature, causing widespread capillary paralysis. In the case of wild or timid animals, due to restraining or compulsory exercise, this condition may develop.3
Secondary shock. This type of shock can be fatal due to its severity. In secondary shock, there is a disproportion between the volume of blood and volume of blood vascular space. Sufficient blood is not present to fill the blood vessels and to maintain the blood pressure leading to lack of availability of blood for pumping out through heart.3
The three categories of shock are:
Circulatory Shock. This happens when there is a decrease in effective circulating blood volume. This category is further divided into the three subcategories of cardiogenic, hypovolemic and distributive shock. Cardiogenic shock occurs when the circulating volume of blood decreases despite normal or increased blood volume. Hypovolemic shock occurs when blood volume is decreased through hemorrhage, third space fluid distribution, or dehydration. Distributive shock occurs when the body is unable to maintain the vasoconstriction of blood vessels.4
The remaining two categories of shock are hypoxic shock and metabolic shock. Hypoxic shock results from impaired oxygen delivery to cells, while metabolic shock involves cells that have become unable to utilize oxygen for energy production.4,5 In this context, the types of shock discussed will be the subcategories of circulatory shock and hypoxic shock, which are the most likely to be brought on due to capture and/or immobilization events.
How Shock Occurs in Camels
The drugs that produce sedation and anesthesia in camels also compromise cardiovascular stability by producing dose-dependent impairment of cardiac function, vascular reactivity and autoregulatory responses.5 Hemoglobin is found within red blood cells and carries oxygen to tissues. Normally, the amount of oxygen delivered to the cell is 2 to 4 times the amount required, depending on the tissue, which ensures an adequate supply.5 However, if tissues are not adequately perfused with blood, the oxygen fails to get to the cells, regardless of the oxygen content in the blood.6
Significant changes in the mean arterial pressure (MAP) trigger changes in heart rate.4,5 An increase in MAP causes vasodilation and bradycardia, while a decrease produces tachycardia and vasoconstriction.2 While anesthesia-related depression of cardiac function and arterial vasodilation are adverse effects that are well-recognized as contributing to anesthetic risk, far less emphasis is generally placed on effects impacting venous physiology and venous return.5
Approximately 70% of an animal’s total blood volume is represented by venous circulation and is a chief contributor to stroke volume and cardiac output.6 Vasodilation is the primary cause of hypovolemia produced by anesthetic drugs. It is often associated with increased venous compliance, decreased venous return, and reduced response to vasoactive substances.4 Contingent upon factors such as patient status and monitoring, a state of relative hypovolemia can remain clinically undetected for protracted periods of time.4-6
Despite their size, camelids (camels, llamas and alpacas) are often agreeable when it comes to handling, thus sedatives and anesthetics are used to provide immobility and analgesia with minimal difficulty. General anesthesia techniques are similar to those for ruminants and horses.1,2 Monitoring core body temperature is essential in camel anesthesia,4 and it is recommended that camels be orotracheally intubated for procedures lasting more than 20 minutes.8
Diagnosis and Treatment of Shock in Bactrian Camels
Clinical signs of shock in Bactrian camels can include any combination of the following:
- Marked hypotension
The treatment of shock must focus on increasing oxygen delivery to the tissues. This can be done by providing supplemental oxygen, increasing effective circulating volume, increasing hemoglobin concentration and increasing cardiac output with stimulants.5,7 If possible, an intravenous catheter may be placed for vascular access. If venous access cannot be established, an intraosseous catheter can be placed. Oxygen supplementation, when available, also provides benefits to the camel experiencing shock. This can be accomplished via flow-by oxygen, mask, nasal cannulas or an oxygen cage.6
In the area of fluid therapy, lactated Ringer’s solution, Normosol-R, and Plasma-Lyte are the preferred choices for resuscitation, as these have been shown to cause fewer complications as well as decrease the risk of mortality4 as compared to other options.
The use of hypertonic saline is also a popular option for increasing vascular volume. This increases plasma osmolarity, pulling water into the vascular space from the interstitial space, thereby expanding plasma volume. It should be noted that hypertonic saline has unwanted side effects, such as a transient, dose-dependent increase in sodium and chloride.4,5 The administration of blood products is an also important adjunct for the treatment of shock.5
2Kulkarni, M.D., et. al. Clinico-Pathological aspects of Shock. Veterinary World, Vol. 2(4):163-165, April 2009.
4Noel-Morgan, J., Muir, W. (2018) Anesthesia-Associated Relative Hypovolemia: Mechanisms, Monitoring, and Treatment Considerations. Frontiers in Veterinary Science, Vol. 5 (53).
5Haller G, Laroche T, Clergue F. Morbidity in anaesthesia: today and tomorrow. Best Pract Res Clin Anaesthesiology (2011) 25(2):123–32.
6Steadman J, Catalani B, Sharp CR, Cooper L. Life-threatening perioperative anesthetic complications: major issues surrounding perioperative morbidity and mortality. Trauma Surg Acute Care Open (2017).
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.
Our pharmacists are also encouraged to develop strong working relationships with our veterinarians in order to better care for veterinary patients. Such relationships foster an ever-increasing knowledge base upon which pharmacists and veterinarians can draw, making both significantly more effective in their professional roles.
The information contained in this blog post is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the medications shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular medication. You should consult your veterinarian about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the medications to diagnose, cure or prevent disease. Medications compounded by NexGen Pharmaceuticals are prepared at the direction of a veterinarian. NexGen Pharmaceuticals compounded veterinary preparations are not intended for use in food and food-producing animals.
NexGen Pharmaceuticals, LLC does not recommend, endorse or make any representation about the efficacy, appropriateness or suitability of any specific dosing, products, procedures, treatments, services, opinions, veterinary care providers or other information that may be contained in this blog post. NEXGEN PHARMACEUTICALS, LLC IS NOT RESPONSIBLE NOR LIABLE FOR ANY ADVICE, COURSE OF TREATMENT, DIAGNOSIS OR ANY OTHER INFORMATION, SERVICES OR PRODUCTS THAT YOU OBTAIN THROUGH THIS BLOG POST.