Chemical Immobilization for Giraffes

The sedation and immobilization of giraffe (Giraffa camelopardalis) is a tricky proposition due to a combination of problems often encountered in such procedures that can result in mortality or morbidity to the animal.1 Giraffes have a unique anatomy and physiology, making them one of the most challenging species to safely immobilize. Their large size makes them difficult to handle and their characteristically long neck, if not controlled, can create a danger to itself and the capture team.

The chemical immobilization of giraffe dates back to the 1960s, when succinylcholine was used to paralyze animals.²Since then, many advances have been made in the refinement of drug combinations used; today, giraffes can safely be captured, walked into trailers and transported due to the dedicated work of researchers, wildlife managers and veterinarians in the field.

There is one species of giraffe (Giraffa camelopardalis) with nine subspecies currently recognized. There are three subspecies which are the most wide-ranging and typically encountered by wildlife managers, usually in sub-Saharan nations such as Kenya and Namibia:

Giraffa camelopardalis tippelskirchi - Commonly called the Maasai giraffe, this subspecies is native to central and southern Kenya.

Giraffa camelopardalis reticulate - Called the Reticulated or Somali giraffe, this subspecies is found in northern parts of Kenya

Giraffa camelopardalis rothschildi - The Rothschild, Baringo or Ugandan giraffe is usually found in protected areas of Kenya including Mt. Elgon, Ruma and lake Nakuru National Parks, Mwea national reserve and several private conservancies/facilities.³

The Giraffe: Safety and Capture Challenges

Immobilization in the giraffe is a challenge because of its unique anatomy and physiology. These present inherent problems during chemical restraint, including:

• The giraffe is a very large animal, with males weighing 790-1,400 Kg and females weighing 700-950 Kg. This limits effective physical control during the critical times of induction and recovery, and limits manipulation once the animal is down.
• If not controlled, the giraffe’s long neck can act as a lever arm, creating a danger to the animal and capture personnel. A poorly-positioned neck can also lead to airway obstruction and/or cramping of neck muscles, which has led to fatalities in the field.
• The giraffe’s long legs potentiate self-induced injury due to slipping during induction and recovery.
• Giraffes have an unfortunate tendency to regurgitate under the stress of capture and immobilization, which can lead to fatal aspiration pneumonia; further, the posterior position of the larynx in the pharynx hampers the draining of rumen and/or saliva. According to Kenya Wildlife Service, “[V]omiting can result from the increased intra-abdominal pressure occurring when the animal impacts the ground since the skin and muscles over the abdomen are very tense. A rumen bolus can on occasion be seen as it progresses up the neck in some giraffes receiving opioids just prior to or during recumbency.”
• Prolonged induction and/or recovery can lead to hyperthermia, myopathy and secondary trauma. While this is true of nearly all exotic mammal species, this is more pronounced in the giraffe, since this species has elevated systolic blood pressure in order to maintain adequate perfusion in the brain.
• The giraffe’s heart has high energy and oxygen requirements to maintain its high blood pressure. If breathing is impaired, even briefly, there is a pronounced danger for heart failure.
• The giraffe has a small respiratory tidal volume with a large dead space and relative small cardiac output during anesthesia. This results in a limited exercise tolerance and considerable resistance to air moving through the long respiratory tract. Thus, while an immobilized giraffe may appear to be breathing, it still may not be getting sufficient oxygen, putting it at risk for heart failure.
• The giraffe has the thickest skin of all ungulates; thus, darting needles must be long (over 50mm) and of sufficient bore gauge to effectively penetrate the skin.
• In most cases, a giraffe will stand up with difficulty after immobilization, especially if a tranquilizer has been used in the immobilization formulation. This potentiates risk factors for injury when the animal is released. (Kenya Wildlife Service, 2019)

While it may be self-evident at this point, the size of the giraffe features prominently in the success of any capture procedure, and smaller animals tend to have better a success rate than the larger adults, since the former are more easily immobilized and restrained.^2,3

Immobilization and Capture

While the immobilization and capture protocols for large wild animals share many similarities, the capture of giraffes is a complex and dangerous procedure, requiring the capture team to plan and organize the actions that the operation requires. It is critical that the capture is well-coordinated. Prior to darting a giraffe, the veterinarian must ensure that all equipment, blind folds, ropes, water and personnel are ready. He or she must also give instructions to the team including human safety issues to avoid any complications during the operation.³ Ideally, the capture team should have a chase vehicle that can get to the darted animal without any delays. If the capture is for translocation, the capture team must have a suitably designed field recovery crate for retrieval and short distance transport to the holding facility. Reversal drugs must be prepared ahead of time and be ready for administration immediately after the animal goes down.

Terrain is an important factor in capturing giraffes, with the ideal terrain being flat or open areas that will allow the capture team to physically bring down the animal when it is sufficiently anesthetized. Darting is typically executed from a vehicle or helicopter. In some cases, darting can be done on foot if the animal is approachable. Darting sites from a helicopter include the rump and back of the hind legs; from the ground (on foot or from a vehicle), the best sites are the shoulder and hindquarters.³ The neck should be avoided. Signs of induction include the giraffe attempting to flee at a markedly slowed pace, stumbling as it runs, holding the head high, drooping of ears and lifting of the muzzle.

The objective during any giraffe capture is to achieve a fast and efficient immobilization with a high dose of the opioid, which is reversed as soon as the animal is down. Longer immobilization times can result in hypoxia and death. According to Kenya Wildlife Service, thiofentanil can be used without a tranquilizer; azaperone can be used with care, as it cannot be reversed. Excessive doses may result in the animal being disoriented and ataxic after the opioid has been reversed. Etorphine and thiofentanil can be combined at a ratio of 20%:80%.³

For the immobilization of giraffe, the Handbook of Wildlife Chemical Immobilization (Arnemo & Kreeger, 2018) recommends thiafentanil (20 mg for males, and 14 mg for females). This can be supplemented with 5 mg of thiafentanil if needed. For reversal, the authors recommend naltrexone (200 mg for males, and 140 mg for females). Alternatively, etorphine may be used at 16 mg for males, and 12 mg for females. This may be reversed with naltrexone at 10 mg for each mg of etorphine given.⁵

Chemical Immobilization of Wild and Exotic Animals (Nielsen, 1999) recommends etorphine in total dosages of 5 to 6 mg with 20 mg of xylazine, or carfentanil in total dosages of 8 mg with 10 mg of atropine and 100 mg of xylazine. The author also reports that in some regions of Africa, etorphine in total dosages of 8 to 10 mg has been used in adult giraffe.⁴

Once the animal is down, the giraffe’s neck should be extended to ensure the airway. The neck should also be supported by at least two capture personnel, with the head maintained above the rumen and the nose pointed down to facilitate drainage of any rumen or pharyngeal fluids.³