Capture events carry inherent risks to wildlife regardless of species, and these risks are more pronounced when dealing with larger species such as deer and other hoofstock. During capture, these risks include such complications as capture myopathy, aspiration, dehydration, hypothermia, hyperthermia, respiratory depression and/or arrest and cardiac arrest.
One complication that is often considered less grave than others, but which may be serious nonetheless, is that of wounds incurred during capture events. Wounds can occur as a result of an animal attempting to flee prior to immobilization, as it loses physical coordination after darting or, rarely, from the darts themselves.1
In recent years, chemical immobilization has become the preferred method of capture (as opposed to nets, traps and other physical restraint) since it significantly reduces the stressors that can bring on the aforementioned complications, but some risks for complications still remain. Some of the listed complications can come about as the direct result of chemical immobilization however, either due to inadvertent overdose, comorbidities or latent sensitivities in individual animals.
In the wild, among the most common threats to wild deer are physical injuries. Animals occasionally incur severe injuries that kill them directly. In other cases, injuries can affect them in ways that are indirectly fatal. These can come about as a result of various events, such as evading predators, fighting for mates or territory and accidents. Even when an animal doesn’t die as a direct or indirect result of an injury, it can be left in a permanently debilitated state or with chronic pain.2
When an animal suffers a wound during a capture event (regardless of the method used for capture), ethical imperatives dictate that the team in the field makes every effort to ensure that the animal is promptly treated so that it can make a complete recovery.
The barasingha deer (Rucervus duvaucelii), also known as the swamp deer, is native to India. Formerly considered an endangered species, today there are fragmented populations in northern and central India, and the barasingha deer has been introduced into several countries as a game animal.3,4 In the United States, this deer may be hunted on carefully-controlled ranches and reserves.
In the 1960s, the total population of barasingha deer was estimated at less than 2,200 individuals in India and about 1,500 in Nepal. The losses leading up to this point were due to overhunting and the conversion of large grassland areas into cropland.4 The barasingha deer was brought back from the verge of extinction over several decades through breeding programs and conservation practices. These measures ultimately led to a substantial increase in the population.3
The barasingha deer differs from other deer species in India in that its antlers have more than three tines. It is from this feature that the deer derives its name, which loosely translates into "twelve-horned" in Hindi. Mature stags often have 10 to 14 tines, and some have been known to have up to 20 tines.5
The barasingha is a large deer with a shoulder height of approximately 45 inches and an overall length of nearly 6 feet. Stags can weigh from 350 to 630 lbs., and females weigh from 290 to 320 lbs. Some larger stags have even been reported as weighing up to 570 lbs.3 Its coat is woolly and yellowish-brown with white spots along its spine. Its throat, abdomen, inside of the thighs and beneath the tail is white, and its coat becomes a brighter orange-brown color in summer. Females are a bit paler in color than males, and the young have faint, light-colored spots.4
Barasingha deer are grazing animals, with a diet consisting of grasses and aquatic plants. During the day, they feed during the mornings and late afternoons. In India, herds comprise from 8 to 20 individuals; large herds may have up to 60 individuals. During the rut, barasingha deer will form large herds of adults. Their breeding season lasts from September to April, and fawns are born after a gestation period of 240 to 250 days in August to November.4,5
Most injuries in barasingha deer that are connected with capture events occur when an animal attempts to flee human pursuers,1 and the most common injuries suffered are lacerations. While remote drug delivery via the dart itself is unlikely to result in a serious injury, darting can on occasion result in minor lacerations. Finally, in some cases an animal may need to be immobilized specifically for the treatment of a serious wound it has suffered due to unrelated causes.
The first order of business in wound treatment is cleaning the wound. If the wound is a small, shallow laceration, this can be done by flushing with a commercial povidone-iodine or other scrub solution. More serious wounds can be flushed with povidone-iodine diluted with saline, and should not be sutured to allow for drainage.1 The literature recommends high volume, high-pressure irrigation unless the tissue is very delicate. The suggested volume for lavage is 50 to 100 mL of fluid per centimeter of wound area.
In cleaning a wound, low-pressure irrigation is gentle to tissues and does not force bacteria deeper into the wound, but it does not debride as well as high-pressure irrigation. The latter can be performed with a pressurized fluid bag or a large syringe with an 18-gauge catheter.2 For suturing more superficial wounds that have been cleaned, a veterinarian should perform the procedure.
Barasingha deer that suffer lacerations prior to or during an immobilization event should always receive systemic antibiotics to reduce the likelihood of infection. Procaine penicillin G combined with benzathine penicillin G is a common formulation is these instances. Long-acting oxytetracycine is also frequently used to treat hoofstock that have suffered lacerations.42
There is no way to guarantee that injuries in target animals will not occur when performing chemical immobilization, particularly under field conditions. However, the drug formulations currently available for immobilizing deer and other wildlife have been refined to a degree that eliminates much of the risk that existed years ago. When using the right drug formulations, and with the proper planning and safety precautions in place, capture teams can have the expectation of effective and incident-free chemical immobilization of barasingha deer in the majority of cases.