TECHNIQUE

Intramuscular Injection of Bears  (Disease Investigation & Management - Treatment and Care)

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Summary Information
Type of technique Health & Management / Disease Investigation & Management / Techniques:
Synonyms and Keywords --
Description Bears may be injected intramuscularly by hand while restrained in a squeeze cage, or using a pole syringe, or using a projectile syringe (darting). (B64.26.w5, J1.15.w11)

Injection sites

  • For intramuscular injections it is important to be aware of the anatomy of bears, in particular the large quantities of subcutaneous fat which may be present over the rump and hind legs in adult bears, especially in hibernating species in late summer and winter, and in polar bears at any time of year. (B345.2.w2, D156.w2, D249.w10)
  • In Tremarctos ornatus - Spectacled bear, appropriate sites with adequate muscle include the shoulder muscle and the side of the neck. The rump is often quite bony, so it is necessary to use a lower site on the hind limb. (V.w99)
  • Administration into the neck, shoulder muscle or upper mid-back may be useful in large/fat adults, rather than into the hind quarters, since the subcutaneous fat layer is thinner, and it is more likely that the injection will reach muscle (which is highly vascularised in these areas). In smaller individuals (harder to hit accurately) or thin bears, injection into the rump minimises the risk of injury. (J1.21.w8, J1.25.w11)
  • The centre of large muscle groups that can drain infections and which the bear can reach to lick are preferred. (D249.w10) For remote injection:
  • Hind leg. (D249.w10)
    • If aimed too high, the needle can strike the bone or cartilage around the hip, or even the spine (backbone). (D249.w10)
    • Too far to either side of the leg and there is a risk of hitting the genitals, the anal canal, the femoral triangle (containing the femoral vein, artery and nerve), or the paunch. (D249.w10)
    • Not suitable in a fat bear, since there may be up to five inches (12.5 cm) of fat covering the muscle. (D249.w10)
    • The hind limb should be avoided in captive bears since there may be a lot of fat present resulting in the drug being deposited in the adipose tissue rather than muscle. (B123.19.w19)
      • Fat deposits over the rump and thighs may be several inches thick. (B16.9.w9)
      The distal (lower) muscle masses of the hind leg may be used, aiming towards the rear of the leg to make sure the femur is not hit. (B345.2.w2)
    • The distal (lower) muscle masses of the hind leg may be used, aiming towards the rear of the leg to make sure the femur is not hit. (B345.2.w2)
    • In Tremarctos ornatus - Spectacled bear, the rump is often quite bony, so it is necessary to use a lower site on the hind limb. (V.w99)
    • Note: in Ursus maritimus - Polar bear there may be a thick fat layer over the rump and thighs; needles at least 2.5 inches long are required if using this site. (D315.3.w3)
  • Shoulder - upper muscular area of the front legs. (D249.w10)
    • A preferred site for injection of captive bears is the triceps muscle area of the forelimb, dorsal to the elbow and caudal to the humerus and scapula. (B123.19.w19)
    • The shoulder is preferable to the rump as there is less fat over the muscle. (B16.9.w9, J1.21.w8)
    • Not too high or the dart may hit the scapular, and it will be hard for the bear to reach the wound to clean it.
    • If you hit too far back, the needle may enter the lungs or the body cavity. (D249.w10)
    • The shoulder is an appropriate site in Ursus maritimus - Polar bear. (B185.37.w37)
    • Note that there may be large fat deposits over the shoulders. (B345.2.w2)
    • This is an appropriate site in Tremarctos ornatus - Spectacled bear. (V.w99)
  • Upper neck - the heavy muscle mass at the top of the neck near the shoulder. (D249.w10)
    • The neck is preferable to the rump as there is less fat over the muscle. (B16.9.w9, J1.21.w8)
    • If too low, you may hit the jugular vein, carotid arteries or trachea (windpipe). (D249.w10)
    • Use a short needle to avoid reaching bone. (D249.w10)
    • Wait until the bear looks away, to minimise the risk of the shot hitting the eyes. (D249.w10)
    • Not suitable for use in young or skinny bears - use the hind quarters instead. (D249.w10)
    • Note the bear is not able to lick this site to clean it. (D249.w10)
    • The neck is an appropriate site in Ursus maritimus - Polar bear. (B185.37.w37)
    • The neck is a favoured site for darting Ursus maritimus - Polar bear. (D315.3.w3)
    • Darting into the neck given the fastest and most predictable response when darting wild polar bears. (B406.37.w37)
    • This is an appropriate site in Tremarctos ornatus - Spectacled bear. (V.w99)
  • In captive bears at short range, injection into the muscles of the forearm can be used, delivered by blowpipe; standard 5 cm 18 gauge or 19 gauge needles can be used. (B407.w18)
  • Note: The time to induction varies depending on the injection site. (B406.37.w37)

Injection methods

Hand injecting (in cubs, usually hand-held, a bear held in a net, or an anaesthetised bear)
  • Choose an area over muscle where the bear is quite clean. 
  • Trim the hair over the intended injection site.
  • Wipe the site with disinfectant.
  • Insert the needle into the muscle. Pull back slightly on the plunger and check if blood enters the needle hub or syringe. If it does, withdraw the needle and choose another site. If it doesn't, then continue.
  • Press down on the plunger to inject the drug.
  • Withdraw the needle.

(D249.w10, V.w5)

Pole injection (bear held in a squeeze cage, snare, culvert trap or other very small area, cubs, or if trained to accept this type of injection)
  • For a bear in a snare:
    • Once the cable is wrapped around a tree, approach the bear carefully, at an angle making it difficult for the bear to swat or bite. Stand quietly until the bear accepts your presence.
    • Gently touch the bear with the "wrong" end of the pole. Repeat this several times until the bear accepts this. If it continues to react aggressively, this option should be abandoned and remote injection used (see below).
  • Choose the muscle mass for injection.
  • Slowly move the pole syringe, with the needle uncovered, towards the bear.
  • Slowly and firmly insert the needle up to the hub and apply pressure to the pole to complete the injection.
    • Do not jab or jerk the needle, as it may break under the bear's skin.
  • Watch the injection site to check no drug is coming out.
  • (D249.w10)
Blowpipe injection (bear in a snare, culvert trap or small cage)
  • Make sure nobody is standing where they could be hit if the dart ricochets. (D249.w10)
  • Preferably steady the barrel by resting it on a solid object. (D249.w10)
  • Wait until the bear is in an appropriate position. (D249.w10)
    • If necessary, for a bear in e.g. a culvert trap, another person can tap or scratch on the side of the trap to distract the bear. (D249.w10)
  • If darting a bear in a culvert trap, take care not to actually stick the end of the blowpipe into the trap, since one blow from the bear could cause you serious injury. (D249.w10)
  • Aim for a large muscle mass. (D249.w10)
  • The shoulder or the rump are appropriate sites. (V.w6)
  • In captive bears at short range, injection into the muscles of the forearm can be used, delivered by blowpipe; standard 5 cm 18 gauge or 19 gauge needles can be used. (B407.w18)
  • Take a good mouthful of air before blowing. (D249.w10)
  • If using a gas-charged blowpipe, make sure the pressure is not too high if you are close to the bear. (V.w6)
Pistol injection (bear in a snare, culvert trap or small cage)
  • For a bear in a snare:
    • Approach carefully to within an appropriate distance (about 15 ft).
    • Extend your firing arm; preferably rest it on a solid object (e.g. tree or branch).
    • Be patient, wait until you can get a good shot before firing.

(D249.w10)

  • Use an appropriate gas pressure or cartridge power for the distance.
    • Excessive pressure or charge for the distance is likely to cause more muscle damage. (V.w6)
  • Do not shoot from too close if pressure/charge cannot be reduced. (V.w6)
Dart rifle injection
  • For free-ranging bears as well as those caught in a snare or confined within an enclosure.
  • Make sure that you are within an appropriate range for the rifle.
  • Use an appropriate gas pressure or cartridge power for the distance.
    • Excessive pressure or charge for the distance is likely to cause more muscle damage. (V.w6)
    • Do not shoot from too close if pressure/charge cannot be reduced. (V.w6)
  • Wait until the bear is in an appropriate position before shooting. 
  • Wait until it is possible to take a shot inside the proper distance. 
  • Wait for a broadside shoot whenever possible. This gives the maximum size of target areas and reduces the chance of the dart angling into a vulnerable area. (D249.w10)
    • Do not try to dart a bear that is facing directly towards you.
    • If it is quartering towards you (angled towards you), aim at the front of the shoulder muscles, or the upper neck, to minimise the risk of the needle glancing off the back of the foreleg muscles and into the body. If aiming for the hindquarters, shoot for the rear of the muscle group to minimise the risk of hitting the inside of the thigh of the other leg, and the femoral triangle. (D249.w10)
    • Aim hindlimb shots for the thigh rather than the rump, to avoid large fat deposits, and towards the rear of the leg to avoid hitting the femur. (B345.2.w2)
  • Wait until the bear is stationary. (D249.w10)
  • Think about the angle at which the dart will hit the target. (D249.w10)
  • A level ground shot is preferable to an upwards or downwards shot; it gives a larger target area. (D249.w10)
    • If shooting upwards at the bear, aim for the higher muscle groups to avoid the dart entering the underside of the body. (D249.w10)
    • If shooting downwards, aim for the lower muscle groups to avoid hitting the spine. (D249.w10)
  • If you cannot see the dart after it apparently hit the bear, note what your target area was; when the bear is immobile, check that area for a dart wound. (D249.w10)

(D249.w10)

Appropriate Use (?)
  • For a bear in a culvert trap: air-powered or CO2-powered pistol, lung-powered blowpipe, or possibly a jabstick. (D249.w10)
  • For a bear in a small cage:
    • Pole-injection (a jabstick) can be used if the bear cannot retreat out of reach.
    • Injection into the muscles of the forearm can be used, delivered by blowpipe; standard 5 cm 18 gauge or 19 gauge needles can be used for this injection site. (B407.w18)
    • Note: Using a lung-powered blowpipe or a CO2-powered blowpipe at a low pressure setting to dart a bear in a cage may be less stressful for the bear than having a human approach closely to hand-inject. (V.w6)
  • For a bear in a snare: 
    • For adult grizzly bears, a dart rifle fired at an appropriate distance, preferably with the bear unaware of the darter's presence.
    • For black bears and young bears: dart pistol or blowpipe; pole syringe if the bear can be closely approached. (D249.w10)
  • For free-ranging bears and those in a large enclosure, a dart rifle fired at an appropriate distance. (D249.w10)
  • Hand injection can be used for wild cubs-of-the-year in spring, and a pole syringe for injecting cubs-of-the-year in autumn (after their mother has been immobilised). (J1.25.w11)
  • Hand injection or jabstick injection may be used as appropriate if a captive bear has been trained by positive reinforcement training to allow this. See: Mammal Handling & Movement - Husbandry Training
Notes
  • Use sharp needles. Blunt needles are likely to fail to penetrate/bounce off the animal, particularly when using low pressures to dart at short distances. (V.w6)
  • Aim hindlimb shots towards the rear of the leg to avoid hitting the femur. (B345.2.w2)
  • Aim upper forelimb shots towards the front to avoid hitting the scapular spine. (B345.2.w2)
Complications/ Limitations / Risk
  • Practice is required before administering intramuscular injections with a remote injection system (blowpipe, dart pistol or dart rifle). 
    • It is important also to be familiar with the individual dart gun being used. (D249.w10)
    • Do not dart a bear using a gun you are unfamiliar with and have not had a chance to practice with - if that is the only gun available, it should be used by someone who is familiar with it. (D249.w10)
    • If using an unfamiliar gun, find the time to load some darts with water and practice; sight in the gun properly. (D249.w10)
    • Do not let anyone pressure you into a hurried shot; wait until the circumstances are right. (D249.w10)
    • Avoid using rifle at distances over 30 yards or pistols at distances over five yards. (D249.w10)
    • Wait until it is possible to take a shot inside the proper distance. (D249.w10)
Risks of injury to the bear
  • Physical injury, sometimes severe or even fatal, can occur when bears are darted. (P9.2004.w4, J40.32.w1, D249.w10)
  • Avoid darting cubs, yearlings and emaciated bears: the appropriate muscle masses are small and the chances of hitting the wrong place are large. (D249.w10)
    • Free-darting a cub carries a very high risk of mortality for the cub. (D249.w10)
  • Excessive pressure or charge for the distance is likely to cause more muscle damage. Severe muscle damage and subcutaneous necrosis can be a risk in any animal if an inappropriate (excessive) pressure of impact or charge is used. (V.w6)
  • Do not shoot from too close if the pressure/charge cannot be reduced. (V.w6)
  • Darts shot with heavy charges can embed into the muscle. Use lower-power charges (brown or green charges for the Palmer rifle, not the heavier red or yellow charges). Do not use gas powered rifles at too high a pressure. (D249.w10)

Inadequate injection

  • If short needles are used they may not penetrate through hair, skin and subcutaneous fat to muscle. (B16.9.w9, B64.26.w5, B185.37.w37, D249.w10, V.w6)
    • Injection into the fat may be ineffective. (B16.9.w9)
  • If blunt needles are used they may fail to penetrate, or may bounce off the animal, particularly when using low pressures to dart at short distances. (V.w6)
  • If dart velocity is inadequate, the needle may not penetrate through fur and fat to muscle. (B185.37.w37)
  • Adult bears, particularly males, may have thick fat over their hind quarters. This is true particularly for hibernating species, in autumn (fall) and for polar bears at any time of the year. Therefore, for intramuscular injections, particularly by darting, or fat bears, use the muscles of the shoulders or upper neck rather than the hind quarters. (B345.2.w2, D156.w2, D249.w10)
    • If you must inject into the hind quarters, a long needle is required. (D249.w10)
    • If the injection does not reach the muscle and the drug goes into fat, there will be no immediate effect. (D249.w10)
Risks of post-injection infection
  • Note: It should be assumed that a dart, particularly a powder-charged dart with a large-bore needle, will have inoculated surface bacteria into the animal. To minimise the risk that a debilitating abscess will form, give antibiotic cover as for a wound (e.g. procaine penicillin/benzathine penicillin, give 22,000 IU/kg of the benzathine penicillin G to ensure an adequate repository effect giving antibiotic cover for 5-7 days, subcutaneously or into the large muscles of the hind legs, with a large bore (18 gauge) needle, at no more than 5 mL per injection site). (B345.4.w4). 
    • Additionally, consider filling the dart wound with topical antibiotic from an intramammary infusion tube. (B345.4.w4)
Equipment / Chemicals required and Suppliers
  • Needles of the appropriate sizes.

    • A needle length of at least 7.5 cm (3.0 inches) is required to reach through the subcutaneous fat layer on adult bears. (B16.9.w9, B64.26.w5)
    • For Ursus maritimus - Polar bears:
      • needles 4.5 cm long for adults, 3 cm for cubs of the year. (J1.19.w10)
      • needles at least 4.5 cm long are recommended. (B185.37.w37)
    • For Ursus americanus - American black bear, needles 2.5-3.8 cm long, 16-22 gauge. (J1.15.w11)
    • Needles may be 18 gauge or 19 gauge. (B64.26.w5)

  • Syringes of the appropriate sizes for injection (or for loading drugs into darts).

  • Remote injection equipment and pole syringes, as required, including:

    • Dart rifle, dart pistol, blowpipe as appropriate.

    • Darts (appropriate for the dart gun/blowpipe and the drug(s) to be used.

    • Needles of an appropriate size of the species, age and body condition of the bear, and the muscle area to be darted.

  • Appropriate medication.

Expertise level / Ease of Use
  • This procedure should only be carried out by an individual with appropriate clinical training and practical experience.
    • In some countries a firearms licence may be required for use of remote injection equipment. See section below: Legal and Ethical Considerations
  • Practice is required before administering intramuscular injections with a remote injection system (blowpipe, dart pistol or dart rifle). 
    • It is important also to be familiar with the individual dart gun being used. (D249.w10)
Cost/ Availability
  • Hand injection is inexpensive unless expensive drugs are being used.
  • Remote injection systems vary considerably in their costs.
  • Note: Darts for remote injection may be home-made quite cheaply. However, commercially manufactured darts are more accurate and are preferable if available.
Legal and Ethical Considerations
  • Dirty needles and syringes must be disposed of properly (needles always into a properly marked sharps container. (D249.w10)
  • In some countries there may be legislation restricting the use of this type of technique to licensed veterinarians. For example in the UK: "The Veterinary Surgeons Act 1966 (Section 19) provides, subject to a number of exceptions, that only registered members of the Royal College of Veterinary Surgeons may practice veterinary surgery." (see: LCofC1 - RCVS Guide to Professional Conduct 2000 - Treatment of Animals by Non-Veterinary Surgeons).).
  • In some countries a firearms licence may be required for use of remote injection equipment.
    • e.g. in the UK, anyone possessing a blow-pipe, dart-gun etc. which can be used to discharge tranquillising drugs (i.e. for remote injection), must be authorised by a Firearms Certificate. This is issued by the police. (B284.5.w5)

Use of Drugs (Medication):

  • Many drugs are not registered/labelled for use in particular wildlife species and care should be taken in their use, with proper regard for possible toxic effects. Consideration should be give to relevant legislation regarding the use of drugs.
  • In any country, drugs are unlikely to be specifically licensed for use in bears. 
    • In Europe the prescription cascade must be followed, and the client's informed consent should be obtained, whenever a drug is used which is not licensed for use in a given species. (B284.5.w5)
    • In the UK, guidelines regarding the use of drugs are set out in the Royal College of Veterinary Surgeons Guide to Professional Conduct 2000: (see: LCofC1 - RCVS Guide to Professional Conduct 2000 - Choice of Medicinal Products).
    • In the USA, the Food and Drug Administration (FDA) regulates specific conditions for the use of drugs in animals and people. The Animal Medicinal Use Clarification Act of 1996 allows extra-label use of approved animal and human drugs under certain conditions, with extra-label use being allowed "in non-food-producing animals if the drug is approved by the FDA, is used by or on order of a licenced veterinarian, and there is a valid veterinarian/client/patient relationship." In food-producing animals (including game wildlife species), additional conditions for extra-label use include that there is no approved alternative drug for such use (or if there is, it is clinically ineffective), the veterinarian has established a substantially extended withdrawal period; the treated animal can be individually identified (e.g. with an ear tag or a collar) and assigned withdrawal times can be assured, ensuring no illegal residues. (B486.11.w11)
  • Additionally, many drugs used for immobilisation are controlled substances in many countries, and appropriate registration/licences, records etc. for the country in which the drugs are being obtained/used must be followed.
  • When highly potent opioids are being administered: 
    • The specific antagonist for humans (naloxone) must always be available and someone must be present who (a) can give the antagonist in the case of accidental human injection and (b) can give artificial respiration if necessary in the case of accidental human injection. 
    • If these drugs are to be used then telephone numbers for one or more local hospitals must be readily available.
  • Note that the laws regarding administration of medical treatment to accident victims, by personnel who may not be officially qualified, vary between countries. (B70.A1.w3, P1.2006.w3)
Author Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referee Suzanne I. Boardman BVMS MRCVS (V.w6)
References B16.9.w9, B64.26.w5, B70.A1.w3, B123.19.w19, B185.37.w37, B284.5.w5, B345.2.w2, B345.4.w4, B406.37.w37, B407.w18, D156.w2, D249.w10, J1.15.w11, J1.21.w8, J1.25.w11, LCofC1, P1.2006.w3, V.w5, V.w6, V.w99

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