Zoo Animal and Wildlife Immobilization and Anesthesia
There is little difference between indigenous or exotic animals in a zoo setting versus in the wild, save for the inherent stressors involved in being in captivity. Whether dealing with a fox or a tiger in a zoo setting, these animals will periodically require veterinary care. As with wildlife in the field, some zoo animals may be handled with minimal or no sedation, while others will require full sedation in order to be evaluated and treated.
Whether or not an animal needs to be sedated is typically a function of the potential risks to the animal and its handlers associated with handling it, and the degree of invasiveness of the procedures involved. If there is a high probability that the animal will injure itself or its handlers during a procedure, it should definitely be sedated; of course, any substantially invasive procedures (such as surgery) must involve chemical immobilization.
Species-Specific Equipment and Protocols
All reputable zoos will have a veterinarian on staff or on-call to serve its inhabitants, and these will generally be veterinarians who have dedicated themselves to treating wildlife in a zoo setting. Veterinarians and wildlife specialists who work in zoo settings often devise novel procedures for restraining animals prior to restraint and treatment, due to the unique construction of enclosures and other animal habitats within the zoo. And of course, different species will require different types of equipment and procedures depending upon their size and temperament.
For example, hooved animals may require handlers to employ riot shields during the restraint process, while leg hobbles, blind folds, ear plugs, lassos and rubber balls for the tips of their horns may be needed for the animals themselves during immobilization. More docile hoofstock can also be trained to use training chutes and tamers so that standing sedations can occur.1
Smaller aggressive animals can sometimes be handled without full sedation, but may require measures such as a rabies pole, burlap bags, heavy leather gloves, towels or nets for restraint. These animals may also be put into an induction chamber or injected with a pole syringe if sedation is needed. Leather gloves, bird hoods, towels, garden gloves, nets and chutes are often used as restraint devices for avian species.1 Most reptiles can be handled using the same equipment as birds, including leather gloves, towels, tongs and snake poles or tubes for restraint.1
Some of the small to medium-sized primates can harbor zoonotic pathogens that are particularly dangerous for humans, although they pose no threat to the animal. Since primate species often bite when threatened, appropriate PPE must be worn by handlers at all times. This would include items like heavy leather gloves, masks, and face shields. Nets, induction chambers or squeeze cages are often used in these instances. Great apes can be particularly dangerous; unless they have been trained to cooperate with aspects of examinations, they may need to be immobilized via remote drug delivery.
Diagnostic Techniques in the Zoo Setting
While wildlife veterinarians are often significantly hampered in their ability to diagnose ailments of animals in the field without sedating and transporting them, the zoo veterinarian usually has all of the diagnostic capability of the veterinarian in a traditional practice setting.
Essential diagnostic techniques include a history of an animal’s health and a thorough visual and physical examination, the latter often requiring anesthesia (depending on the species). The ease of sample collection for laboratory testing (CBC, biochemical profile, serology, cytology); fecal examination for parasites; urine for urinalysis; and aerobic, anaerobic, fungal, and viral culture all depend upon species anatomic differences. Radiography and ultrasonography are commonly done. Endoscopy, laparoscopy, and minimally invasive surgery are used when indicated, with use of CT and MRI becoming more common.2 In general, nearly any technique used in a practice can be modified for use in zoo species.
Drug Delivery in the Zoo Setting
Many animals in the zoo setting can become quite tolerant of restraint and examination. In these cases, the animal may receive drugs just as any domestic animal would. In the case of new animals, or those that remain uncooperative, the use of a pole syringe or compressed gas projectors such as blowpipes, or CO2 rifles and pistols may be needed to administer drugs via remote delivery1
Drug administration in the zoo setting can be challenging. Oral medication has the advantage of minimal disturbance to the animal, but ensuring adequate individual intake may be a problem, especially when animals are housed in a group.2 Mixing sedation medications with food can be helpful. Oral antibiotics in hoofstock and other species can disrupt normal bacterial flora and lead to GI problems; oral sedative or anesthetic administration can result in variable onset, duration, and depth of effect because of inadequate consumption or delayed absorption. IM injections with a hand syringe can be difficult unless a restraint device or other means of physical restraint is used. Remote IM injections may be made by firing a projectile syringe from a dart gun. However, these injections may be painful and add the trauma of dart impact and injection, especially when delivering large volumes over long distances.2
There are few drugs that are approved for use in zoo species, but extra-label drug use laws allow drugs to be legally used in species for which they are not licensed. Providing quality medical care to zoo animals requires that medications be used without documented therapeutic benefit, dosage, treatment schedule, contraindication, and toxicity data in these species. Whenever possible, drug administration should be based on pharmacokinetic data.2
Anesthesia in the Zoo Setting
Many procedures routinely accomplished on domestic animals with minimal restraint require anesthesia of zoo animals for the welfare and safety of both animals and personnel. Before anesthesia of a zoo animal, the veterinarian should be familiar with the species and choice of anesthetic agent. Anesthesia records for the individual, other specimens of the same species in the collection, or published references for the species should be reviewed.2
A variety of factors influence an animal’s response to anesthetic drugs, including age, sex, stage of reproductive cycle, general nutritional status, and most especially mental state before drug administration. An excited animal usually requires more of a given drug; once anesthetized, it has a greater tendency to develop capture myopathy secondary to hyperthermia, respiratory depression, and acidosis.2
Airway Management. Once an animal is sedated sufficiently to be approached, evaluating the airway is one of the first priorities. Anesthesia often leads to hypoxia, so it is essential to make sure that the animal is breathing on its own.1 If the animal is breathing well on its own, for some procedures, an unsupported airway may be used, but for invasive procedures, most veterinarians will choose to intubate.
The Unsupported Airway. An airway is unsupported when the sedated animal is relying upon the viability of its own airway while under sedation. When the anesthetist is relying solely upon an unsupported airway, the neck should be extended and the tongue should be pulled forward and laterally out of the mouth. An unsupported airway presents the highest risk for aspiration, especially in ruminants. To decrease the chances of aspiration, the nose of the animal should be positioned lower than the larynx. This will reduce the possibility of gastrointestinal fluid passing up the esophagus while also allowing the oral cavity to passively drain.1
Endotracheal Intubation. Intubating can be difficult when dealing with unique species. A knowledge of the species’ tracheal anatomy is very important prior to a procedure. Birds and most reptiles have complete tracheal rings unlike mammals, who have C–shaped tracheal rings. This unique anatomy changes the type of endotracheal tube that may be used. For mammals, an endotracheal tube with an inflatable cuff should be used, whereas in birds and certain reptiles, a non-cuffed endotracheal tube must be used so the trachea isn’t damage by the inflatable cuff.1
Depth of anesthesia should also be monitored frequently throughout any procedure. If anesthesia is too light, staff members could be put at risk; if too deep, the animal may not recover. Every procedure performed on animals in a zoo setting should have a solid monitoring plan.
1Exarhos, B. Zoo Animal Anesthesia and Procedures. Michigan Veterinary Medical Association Journal, No. 324; March, 2012.
2Merck Veterinary Manual.
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.
Disclaimer
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.
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