Wounds in Axis Deer During Capture and Chemical Immobilization

Capture events carry inherent risks to wildlife regardless of species and the capture method used. These risks tend to be more pronounced when dealing with larger species such as Axis deer and other hoofstock in the field. During capture or chemical immobilization, these risks include such complications as capture myopathy, aspiration, dehydration, hypothermia, hyperthermia, respiratory depression and/or arrest and cardiac arrest.

Due to the reduced level of stress on wild animals resulting from chemical immobilization—as opposed to traps—and the refinement of drugs over the years, this has become the preferred method of immobilizing wildlife for research, study and wildlife management. Some complications can still come about as the direct result of chemical immobilization however, either due to inadvertent overdose, comorbidities or latent sensitivities in individual animals.

Wounds incurred during capture events may be considered less critical than some other complications, but these must still be seriously considered. Wounds can occur as a result of an animal attempting to flee prior to immobilization, as it loses physical coordination during take-down after darting or, rarely, from the darts themselves.¹

Physical injuries are among the most common threats to wild deer. In some cases, animals can incur severe injuries that kill them directly. In other cases, their injuries can affect them in ways that are indirectly fatal. Aside from human-related causes, these can come about as a result of many 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 compromised state or with chronic pain.²

When an animal suffers a wound during capture/chemical immobilization, ethics dictate that those undertaking the required research or wildlife management protocols make every effort to ensure that the animal is promptly treated so that it can make as complete a recovery as is possible.

Axis Deer Background

There are approximately 40 species of deer spanning the globe. While most of these are found in Asia, deer remain one of the most popular big game species in North America. Deer occur on all of the continents except Australia and Antarctica, although many species have been introduced outside of their original habitats as game animals. In all save one species of deer, only the males carry antlers; in the reindeer or caribou (Rangifer tarandus), both sexes have antlers.⁴ Antlers are usually branched and serve as sexual ornamentation as well as weapons during the mating season.

There are seven species of deer that are native to North America, with numerous sub-species. They range from northern Canada through Central America, and from the east coast of the North American continent through the west coast.

The native range of the Axis deer (Axis axis, also known as the chital deer) is the Indian subcontinent. It is a fairly large, spotted deer that was introduced into the southwestern U.S. in the early 1900s. Axis deer prefer sparse forested areas with adequate water and shade, tending to avoid rugged terrain.⁵

Axis deer are social animals that are usually found in herds ranging from a few individuals to more than 100 animals. Herd leaders are usually mature, experienced does. Unlike native North American deer, adult male Axis deer are normally found living with herds of young and old animals of both sexes. Like elk, rutting male Axis deer emit bugle-like bellows, and both sexes can generate alarm calls when threats are present.⁶

Axis deer reproduce in a manner that is said to be similar to that of domestic cattle. In the wild, mature bucks in rutting condition may be found throughout the year, with each buck apparently having an independent reproductive cycle which may not be synchronized with that of other bucks in the herd.^6,7 Females experience estrous cycles throughout the year, with each cycle lasting approximately three weeks. While pregnant females may be found year-round, most breeding lasts from mid-May through August.

Axis deer feed primarily on grass in fields near wooded or sheltered areas. They can be found in open areas during warm periods of the day, but are primarily active at dusk or dawn. Since they prefer warm weather, they tend to thrive in warmer areas, such as the state of Texas, where they have a robust and growing population.⁷

Treating Wounds in Axis Deer

Most injuries in Axis deer that are connected with capture events occur when an animal attempts to flee human pursuers,¹and 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. In some cases, an animal may need to be immobilized specifically for the treatment of a serious wound it has suffered due to other causes.

Cleaning the wound is the first step in addressing the situation. If the laceration is small and shallow, 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 generally not be sutured to allow for drainage.¹ The literature recommends high volume, high-pressure irrigation unless the tissue is very delicate. The suggested lavage volume is 50 to 100 mL of fluid per centimeter of wound area.

Low-pressure irrigation may also be used because this is gentle to tissues and does not force bacteria deeper into the wound, and it does not debride as well as high-pressure irrigation. Either may 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.

Axis deer receiving lacerations prior to or during an immobilization event should 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.²

Considering the risks associated with chemical immobilization, there is no way to guarantee that injuries in Axis deer will not occur, particularly under field conditions. The drug formulations currently available for immobilizing wildlife have been refined to a degree that eliminates much of the risk that existed years ago, however. With the right drug formulations, proper planning and safety precautions in place, capture teams can have the expectation of effective and incident-free chemical immobilization of Axis deer in most cases.