Injuries caused by snares
Injuries caused to tigers caught in poacher’s snares are often both severe and life-threatening unless the trapped animal is detected and given appropriate veterinary care without delay. In field conditions this is a considerable challenge as detection can take several days and appropriately trained personnel are rarely on-hand to conduct a rescue. As a result, snare injuries generally carry a poor prognosis, which worsens as the interval between capture and rescue increases. Unfortunately, this has become a significant problem in most tiger range countries.
It is self-evident that considerable effort should be put into prevention and snare clearance. Given that the speed of detection and rescue is critical in achieving a positive outcome, it is also evident that as there will be a need to train non-veterinary staff to conduct rescues rather than relying on qualified wildlife vets always being available.
Snares are lengths of line comprised of a noose and a free-running eye which entrap an animal’s leg, neck, or body by constricting around the body part and biting in under pressure, preventing the animal from escaping. Neck snares have a noose set for the animal’s head to enter – as the head moves forward, the noose tightens. Foot snares are placed horizontally on the ground and are designed to close on an animal’s leg to restrain it. In both cases, the snare is anchored (usually to a tree) to prevent the captured animal escaping. Here the term ‘snare’ refers to the whole assembly, whereas the term ‘noose’ specifically refers to the catching part. Many different types of snare are used by poachers, but snare nooses of at least 4mm diameter braided steel cable are generally required to restrain a tiger. There have been incidents of tigers being caught in rope snares or 2mm braided steel snares, but these are the exception (Pickles, pers. Comm. 2020).
The strongest form of snare is composed of a single material, such as a single cable from the noose to the anchor point and this is more generally the case with tiger snares. However, this is both expensive and heavy to carry into a forest, so poachers may compromise and use the steel cable only for the noose itself with a short length of running line tied to an anchor line made from a different material.
As a snare noose can tighten without limit, the more an animal struggles the tighter the noose becomes. Snares are generally non-selective and therefore tigers can be caught in snares set for other species such as deer or wild boar. Tigers are caught in both neck snares and foot snares.
(It should be noted that Aldrich foot snares used to capture large carnivores when resolving human-tiger conflict situations or for research purposes such as radiocollaring are designed to minimise injury to the captured animal. The extent to which the noose can close is limited and wildlife biologists are mindful about limiting the trauma and pain caused. Further, these snares are generally checked on a very regular basis to reduce the time a tiger is caught in one.)
Physical injuries and related disease conditions caused by snares:
Most tigers that have been caught in a snare will be suffering from one or more of a wide range of medical problems, including physical trauma and more general or systemic conditions. The extent and severity of all these problems are related to the length of time a tiger is restrained in the snare – the longer a tiger remains in a snare the more its life is in danger.
Physical injuries: These are caused directly by the progressive tightening of the snare noose, from the animal’s attempts to chew through the snare, and by trauma on surrounding objects in attempts to escape.
- A noose tightening around any part of the body will lead to restriction or elimination of blood supply to the area (“ischaemia”) eventually resulting in necrosis of the affected tissues. (The term “necrosis” means the death of body tissue – an irreversible injury.) A tiger’s reaction to being caught in a snare is generally to fight against the restraint, but the more it attempts to pull away the tighter the snare noose becomes, biting into and through the skin and underlying tissues. In leg snares, constant tugging may even cause the noose to shear away flesh, in some cases stripping it down to the bone which may subsequently fracture. In extreme cases the animal succeeds in tearing its own foot off in the struggle. In the case of a tiger snared around the neck, damage can occur to the vital structures such as major blood vessels, nerves, trachea, larynx and oesophagus, and vigorous struggling may lead to death by asphyxiation.
- Tissue necrosis caused by ischaemia is not a quick process, developing over ~ 72hrs. Therefore, if a tiger is released from a snare and immediately freed because no serious injury is evident, it is possible that necrosis of the body part affected may develop during the following few days when it is no longer under observation. (This scenario is only likely in tigers that are rescued within 24hrs of being trapped in a snare). Necrotic tissue is very prone to secondary infection with bacteria or maggots which itself could lead to the death of the animal days or weeks after release. Careful consideration should be given to what damage a snare could have caused when considering immediate release.
- Attempts to chew through either the snare noose or anchor cable can result in significant fracturing of teeth and laceration of gums. This is not only painful, but even if the tiger is released successfully from the snare broken teeth may affect its ability to catch prey in the future.
- In their attempts to free themselves from a snare, tigers can injure other parts of their body on surrounding objects.
- Haemorrhage into the lungs and heart muscle may result from vigorous escape attempts due to severely elevated blood pressure.
Systemic problems: Even if the wounds caused directly by the snare are not life-threatening, there are more general conditions that often are. Therefore, unless these problems are addressed at the same time as physical injuries, the chances of successful rescues are low.
- Dehydration and shock
- Lowered blood glucose and starvation (especially in smaller or young individuals)
- Hypo- or hyper-thermia
- Open wounds can rapidly become infected by bacteria and/or maggots. In cases of severe infection, terminal septicaemia may develop.
- Although many species are prone to developing capture myopathy (potentially life-threatening muscle damage caused by extreme muscular exertion) when caught in snares, reports of this condition in large carnivores are rare. However, damaged muscle and its break-down products could contribute to the death of a tiger in the days or weeks after release from a snare.
- Severe stress and pain are likely to be experienced by a snared tiger.
- Females may be prevented from returning to dependent offspring, who will subsequently die of starvation.
Approach to the snared individual & assessment of situation:
The assessment of the situation is one of the most critical phases of a rescue and requires careful thought and in-field planning. A bad approach can lead to a bad outcome for the injured tiger and reduce the chances of a successful rescue. NB: Tigers caught in snares are extremely dangerous.
Before approaching the tiger, it is helpful to collect some information/ history from local community members such as when the tiger was snared, who snared it, whether anyone has attempted to free it, etc.
Then proceed as follows:
- When a snared tiger is encountered keep well back out of view of it to reduce struggling.
- Nominate a responsible and suitable person to be the incident controller (usually the team leader). This person will take control of the situation until its resolution. They will make the decisions about how the rescue proceeds, if it should be aborted, and when additional assistance will be required.
- Minimising further stress to the snared tiger is a key principle throughout the rescue.
- Establish a 50 m perimeter around the animal into which no-one is allowed without the instruction of the incident controller.
- The incident controller should establish communications with appropriate headquarter staff if applicable.
- Two people (usually the incident controller plus one other armed at least with a flare to be used in case the tiger breaks free of the snare and poses a danger to staff) go carefully & quietly forward to assess the situation – level of danger to staff, condition & size of tiger, is the tiger weak or strong? (depressed/moribund or active and alert?), approximate body weight & age, gender, extent of injuries, etc. Much of this can be achieved with binoculars. When approaching a snared animal keep quiet and try to avoid the tiger charging against the snare – it will only make the damage worse. If it does respond in this way, back off to a greater distance. It is extremely important to establish whether the tiger is still held securely in the snare and that the anchor cable is still anchored to a fixed point. It is quite possible that a snared tiger could break the anchor cable and move away, only to collapse nearby. In that case the snare noose will still be around the cat’s foot / neck etc, but the cat will not be held by the anchor cable. Such a tiger is an extremely dangerous animal despite appearing to be in a weakened state.
- The two people retreat and a plan of action should then be worked out with all the team. The chances of a successful outcome can be considered at the same time.
- Planning the rescue must include consideration of the following aspects:
* The urgency of the situation
* Whether additional resources and/or manpower are required, and their availability. This might include veterinary equipment, consumables, and expertise. However, a rapid response is always essential, and delays in responding will only make the prognosis worse.
* If the site at which the tiger has been snared is not appropriate for conducting the necessary veterinary procedures a nearby location must be identified and means to move the animal safely to it sourced.
* If the animal needs to be transported over a longer distance (eg to a rehabilitation centre), arrangements will need to be made, and a transport cage sourced or constructed. Personnel at the animal’s destination should be prepared to accept the animal with a suitable enclosure, food and water.
- Be prepared to intervene early if the animal’s health deteriorates while waiting for all resources to be assembled – though this must not compromise human safety.
- If possible and without stressing the tiger further, consideration should be given to providing an accessible source of water to reduce dehydration.
- To prevent further stress, struggling and injury, it is essential to prevent anyone unnecessarily approaching the snared tiger (for example: local people, journalists, rescue team members) at this stage. Protect the animal at all times from poachers if waiting for help to arrive.
- Everybody involved with the rescue must be clear what their role is and be well-briefed by the incident controller about what to do and when to do it.
- In nearly all cases darting will be required. The incident controller should thoroughly brief the person who is to perform the darting, anaesthetic drugs and darts must be carefully prepared and the dose rate calculated based on the animal’s estimated weight. Prior to administering the drugs, the dose rate should be checked by another competent person.
- Prepare intravenous fluids, resuscitation and other veterinary supplies prior to darting. (include emergency drugs – doxapram, adrenaline etc, and the consumables needed for fluid therapy).
- Anaesthetise & treat as below. Do not approach the animal until fully anaesthetised or sedated.
- If possible, take photographs and document each incident in writing for training and prosecution purposes. Do not use flash until tiger is anaesthetised – it will only cause more stress.
Given the wide range of direct and indirect problems caused by snares, it is not surprising that successful treatment is not straightforward. The treatment of snared tigers must always address both the physical injuries and the systemic problems, but the simple fact is that although some snare injuries can be treated successfully, many cannot.
A rapid response is essential, which requires trained and suitably equipped rescue teams. Delays in responding reduce the chances of success. A live snared tiger is an emergency and they rarely survive removal from the snare if they have been trapped in it for many days.
Ideally, wounds are treated at the field site and medical treatment is given to counter shock/dehydration, infection, tissue swelling and pain, following which the cat is released. However, this is likely only possible in a minority of cases in which the injury caused by the snare is relatively minor, and the tiger has not been in the snare for much more than 48hrs.
Other cases may require first aid in the field (fluids, wound care, etc), followed by removal to temporary rehabilitation facilities to recover over < 14 days or so. This short-term period of captivity would be used to discover whether the injuries sustained are fully understood, and to provide more specialist veterinary care where necessary. Unfortunately, suitable facilities are rarely available or sited within a practical distance. If this is the case, treatment must be attempted in the field. If in-field treatment is not likely to allow the tiger to be returned to the wild successfully (eg: if loss of a front foot is evident or inevitable), euthanasia or permanent removal into captivity may need to be considered.
The following approach to treatment is suggested:
- Anaesthetise: It will be necessary to anaesthetise any tiger caught in a snare. As tigers that have been caught in a snare for any length of time are likely to be suffering from a degree of dehydration and even shock, medetomidine-ketamine is not recommended as the anaesthetic induction agent. Lowering of blood pressure and consequent reduction in the blood flow through the kidneys, plus the respiratory depression caused by this combination could compromise the animal further. Combinations of medetomidine and Zoletil, or Zoletil alone are recommended. Lower doses of anaesthetics should be used than are appropriate for routine tiger anaesthesia if the cat has been in the snare for longer than 24hrs. (Lists of anaesthetic drugs, equipment and consumables can be found here and as downloadable pdf’s at the end of the page.)
- Once anaesthetised safely, the first priority is to secure the tiger for the safety of the team. Hobbles should be considered.
- A full clinical examination is desirable to determine the extent of both physical and systemic problems. A rectal temperature must be taken.
- Counter shock & dehydration: Establish an intravenous drip using lactated Ringers and give at least 20mls / kg lactated Ringer’s solution rapidly. More may be required in cases of shock. Where an IV line cannot be set up, it is still worth giving the fluids subcutaneously although this is far less effective. Do not give more than 100mls fluid subcutaneously in any one location. Intravenous solutions containing glucose solutions may be necessary if the snared tiger is a cub.
- Address hypothermia or hyperthermia.
- Remove the snare, clean the damaged tissue and assess the extent and severity of injuries. (Remember to remove all components of the snare from the site and retain for later investigation) Equipment will be needed for snare removal including pliers and steel cable cutters.
- The treatment of physical injuries is much the same as for other wounds.
- If only minor local damage has been caused by the snare (eg: swelling of the foot or other part distal to the snare loop due to obstruction of superficial veins with no laceration of the skin) treatment can consist of removing the snare and medicating with non-steroidal anti-inflammatory / analgesic drugs and long-acting antibiotics. If no other medical problems are identified the tiger may be released. These cases are rare and will likely only be seen if the tiger is removed from a snare within 24hrs.
- Minor skin wounds should be thoroughly cleaned with a diluted antiseptic scrub such as “Betadyne” (an iodine preparation) after clipping away the fur around the injury. Make certain that all clipped hair has been removed. If no antiseptic scrub is available, use 0.9% salt solution (~ 2 teaspoons of table salt in I litre cooled boiled water). Spray antiseptic iodine on the area after drying.
- More serious snare injuries where the snare noose has cut through the skin and underlying tissues need critical assessment. Obviously necrotic tissue (see picture above) will not heal and will decay over the following days. The foot is therefore lost and the tiger effectively becomes 3-legged. Although debridement (the removal of dead tissue by surgical or non-surgical means) is the standard therapy for necrosis, removal of significant amounts of necrotic muscle, tendon, nerve and bone from a foot will not restore function, and again the foot is lost. If no blood supply can be identified to a foot below the snare it is likely to become necrotic even if it is not evidently so when examined. Severe snare injuries involving a front foot with evidence of necrosis or impending necrosis are generally unsuitable cases for successful return to the wild.
- Snares injuries around the neck often carry a better prognosis than around a foot if vital neck structures are not damaged (blood vessels, nerves, oesophagus, trachea, larynx). Treat any wounds around the neck as below.
- Clean any other wounds and assess. Minor abrasions and superficial wounds can simply be sprayed with antibiotic solutions.
- If wounds require suturing, clean area thoroughly with diluted “Betadyne “, and suture the wound with simple, individual stitches using a dis-solvable suture material such as “Vicryl”. Use a surgical kit to do this and make all attempts to keep the wound, the instruments and the suture as clean as possible during the procedure. Spray the area with antiseptic iodine after completing the wound repair. These stitches will dissolve in a few days. Beware of fractures in the affected foot – these carry a poor prognosis.
- In all cases give long-acting, broad-spectrum antibiotics. Long-acting preparations of penicillins, tetracyclines and cephalosporins are available and suitable for use in tigers. See Drug Formulary
- In all cases there is likely to be a degree of swelling distal to the snare’s noose. Give carprofen (“Rimadyl”) at 2mg per kg by subcutaneous injection. This is a potent anti-inflammatory and provides a degree of pain relief lasting < 48hrs. DO NOT USE OPIOID PAIN KILLERS EVEN IF THEY ARE AVAILABLE.
If a tiger dies during the rescue attempt, or is euthanased, necropsy by a veterinary pathologist is recommended.
Snare injuries in tigers generally carry an extremely poor prognosis, which worsens as the interval between capture and rescue lengthens. Rescue attempts need to be made as quickly as possible, and rescue teams must be equipped and trained to deal with these situations without delay.
Perhaps in the future, development of temporary, mobile field rehabilitation facilities could be explored as an option to provide more comprehensive veterinary care of tigers that cannot be returned to the wild immediately after rescue.