For physical exams as well as nutritional, reproductive or veterinary research projects physical restraint devices can be very valuable.
Numerous institutions have constructed permanent physical devices to restrain their rhinos when necessary. These physical restraint devices are also called chutes. In general, it is highly recommended that institutions modifying rhino exhibits or constructing new ones incorporate a physical restraint area or device into their design considerations. Several physical restraint designs are effective for rhinos. In general, major restraint chute design considerations include strength, durability, type and function.
It should be noted, that available space and animal’s size and disposition vary across institutions and should be individually addressed. Both captive managers and researchers emphasise that the general restraint area should be an active component of daily rhino management. Methods to accomplish this vary. A restraint chute or restraint area can be designed so that the rhinos must pass through it to exit the barn into the yard. If rhinos are fed indoors, part of the feed can be offered in the chute area. Rhino chutes should be manufactured out of steel or a combination of steel and steel-reinforced wood. Steel-strength aluminium has also been used. Aluminium is lighter and more manoeuvrable than steel, as well as potentially less stressful to rhinos because of lower sound properties than steel. It is important to give the rhino time to get used to the chute so that it is calm and relaxed while being restrained. Depending on the temperament of the individual this may take many months to accomplish.
Restraint chutes: Permanent pass-through indoor restraint chutes are especially effective for rhinos. The chute should allow restraint of the animals when it is passing through in either direction so that shifting routine of the animal is not interrupted. The width of the chute should limit side-to-side movement while still allowing the animal to comfortably lie down. However, animals can become wedged in tight-fitting chutes if the side cannot be released. To alleviate excessive forward movement of the animal when it lowers its head, two vertical bars that push in from sides of the chute to the shoulder of the rhino may be utilised. Quick release of these shoulder bars often relieves agitated animals without having to release them completely.
High-walled chutes: High-walled chutes or bars over the top keep the animals from climbing or rearing up. Horizontal bars in the chute’s entry gates and sides are hazardous for examiners when the animal lies down. Vertical bars on the sides can trap researchers’ arms if the animal can move forward. If the animal’s movement forward and side-to-side mobility can be limited, vertical bars or walls on all sides are recommended. The distance between these bars along the sides of the chute should be great enough to prevent the animal’s foot from becoming wedged if the animal rolls on its side in the chute. For researcher safety, this distance can be divided with removable vertical bars.
Closed chute: A closed chute is another option that has been used successfully. A typical closed chute has both front and back gates. The back gate restricts the rhino’s movement by sliding forward. The hind end of the rhino is supported by a v-design that prevents it from lying down. This design also allows additional safety for the staff while working with the animal. In many respects, a closed chute does not depend as strongly on conditioning of the rhinos as does a squeeze chute, though acclimation is recommended prior to attempting any treatments within the chute. The design of a closed chute might necessitate an outdoor location in most cases, thus the use of this type of chute may be limited by weather.
Free-stall chute: A free-stall chute can be used for animals more sensitive to a confined enclosure. The design of this type of chute allows the rhino to enter or exit at its will and thus may help to keep rhinos calmer during procedures. Because there is free access rhinos must be conditioned to target or stand still. A free-stall design can easily be incorporated into an existing pen or stall, indoor or outdoor. As stated, the open back of this type of chute allows the animal to enter and leave the structure at will. Protection of staff when working with the rhino is important, and a partial back wall constructed of vertical pipes allows staff to step out of the way.
Sliding gates: Sliding gates are safer than swinging doors because rhinos may slam swinging doors. A rectangular opening in these gates for performing palpation should not pin the arm of an examiner when the animal is shifting. The distance between the vertical sides of this rectangular opening must be wide enough for researcher safety while still limiting the space through which a rhino could squeeze. Also the horizontal bottom bar of this rectangle should be only a few inches from the ground, as animals frequently lie down. Solid doors on the outside of these gates can be used to stop rhinos, as they may attempt to charge even small openings. Additionally, good lightning and accessible electrical sources are useful. Guillotine gates are not recommended.
Immobilisation: Besides early crate training prior to transportation, immobilisation offers a fairly simple way of crating a rhino. The usual pre-immobilisation should be observed for any procedure requiring the use of chemical immobilisation/tranquilisation agents. For rhinos, etorphine (M-99, Large Animal Immobilon) remains the drug of choice although several alternatives are available. The duration of immobilisation without administration of an antagonist may range from 30 minutes to two hours. Other drugs used for immobilisation in combination are butorphanol, detomidine, xylazine and ketamine.
Following crating, all rhinos should be held for 24 hours at the loading location for observation, or accompanied by a veterinarian during transport. This is necessary because renarcotisation is common in hoofed animals, especially rhinos, given opioids. Trained personnel should be present to administer the correct reversal agent(s) in the likely event of renarcotisation. Any other complications of crating can be managed more easily and effectively in-house rather than en route.
Several principles should be followed to increase the safety of chemical restraint procedures for both the animals and personnel:
When applicable, antagonists to the restraint drugs should be prepared prior to the initiation of the procedures and should be available for rapid administration.
Careful monitoring of the patient (auscultation, ECG, pulse-oximetry, etc) will help to rapidly identify problems should they develop and allow early intervention.
The large size of an adult rhinoceros may result in further complications during anesthetic procedures. Efforts should be made to maintain the animal in sternal recumbancy when possible to minimize respiratory complications, and if the procedures is to last more than 30 min. efforts should be made to “pad” the area under the animal (with mattresses, inflated inner tubes, straw/hay bedding, etc.) to minimise the effects of pressure on the limbs.
The kind of catching/restraining that is preferred is physical restrain or chemical restrain. When a rhino is being caught/restraint risk of injuring the horn needs to be taken into account.