Wounds in Eld’s Deer During Capture and Chemical Immobilization

Deer are known as cervids (family Cervidae) and belong to the order Artiodactyla, which are hoofed mammals with an even number of toes on each foot. They are also members of the suborder Ruminanti; like cattle, they are ruminants, or cud-chewing plant-eaters. ^3,4 There are seven species of deer that are native to North America, with numerous sub-species and others that have been introduced. They range from northern Canada through Central America, and from the east coast of the North American continent through the west coast.

The Eld’s deer (Rucervus eldii) is a tropical species of deer that is native to the lowland forests of southeast Asia.³ Due to hunting and habitat conversion, populations of this deer have significantly declined in their native range and are now severely fragmented. Today, Eld’s deer occur in several protected areas throughout their former range and have been introduced into numerous other countries as game animals.

There are three subspecies of Eld’s deer:

• The Sangai (Rucervus eldii eldii) of northeast India. Once widespread in the Manipur Valley, this subspecies was declared extinct until it was rediscovered in Keibul Lamjao National Park.
• The Thamin (Rucervus eldii thamin) of Myanmar and western Thailand. This subspecies was once distributed widely in the central plains of Myanmar, but is now reduced to two major populations.
• The Siamese Eld’s Deer (Rucervus eldii siamensis) of Indochina and China’s Hainan Island. This subspecies once roamed Thailand, Laos, Cambodia, Vietnam and Hainan.⁴

The Eld’s deer is a large deer that is considered graceful in appearance. Similar in size to white-tailed deer, Eld’s deer differ somewhat in body type. Their legs are long and thin, and they have slender bodies with a large head and ears. Their rough coats change color with the season. In summer, they are reddish-brown, and dark brown in winter. Stags often have darker coloring than hinds (females) and have a thick mane of long hair around the neck.³

For food, Eld’s deer graze and browse on wild fruits and cultivated crops such as rice, lentils, corn, peas and rape from nearby fields. Rucervus eldii thamin has been reported to eat the fruits of various woody plant species, and also eat forbs and grasses in these areas.⁵ The Eld’s deer is often associated with areas that are seasonally burned, since they are often found eating new grasses as they emerge after a burn.³ Their feeding may vary seasonally with food availability and with reproductive considerations; during rut, males often experience a decline in body weight, probably due to a decrease in their food intake.

While Eld’s deer are usually solitary, they will form large groups or herds on occasion as an adaptation to avoid predators. These larger groups decrease the risk of predation, both by increasing the chance that a predator will target other animals rather than a lone individual, and by the increased vigilance for predators which can be provided by all members of the group.⁴ The most common predators of Eld’s deer are tigers and leopards.³

As is the case with most cervids, Eld’s deer mothers hide their fawns in underbrush immediately after birth. They usually give birth during the cool-dry season when the flood waters have receded and vegetation has begun to grow, which provides the young with shelter and helps to conceal them.⁵ Fawns are weaned after 4 to 5 months, which allows them to have sufficient time to increase their mobility and ability to travel with the herd.^3,4

Risks for Wounds in Eld’s Deer

Capture events carry inherent risks to wildlife regardless of species or the method of capture used. These risks are often more pronounced when dealing with larger species such as deer and other hoofstock in the field. During capture/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 of the listed 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.

One complication that is sometimes considered less serious than others, but which must be considered, is that of wounds incurred during capture events. These can occur as a result of a deer attempting to flee prior to immobilization, as it loses physical coordination during take-down after darting or, rarely, from the darts themselves.⁶

Physical injuries are one of the most common threats to wild Eld’s deer. In some cases, animals can incur severe injuries that kill them directly. In others, their injuries can affect them in ways that are indirectly fatal. Injuries 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 compromised state or with chronic pain.⁷

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

Treating Wounds in Eld’s Deer

Most injuries connected with capture events in Eld’s deer and other large hoofstock are experienced when an animal attempts to flee human pursuers,⁶ 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 other causes.

Cleaning the wound is the first step in addressing the situation. 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 lacerations can be flushed with povidone-iodine diluted with saline, and should generally not be sutured to allow for drainage.⁶ 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 is gentle to tissues and does not force bacteria deeper into the wound, but it does not debride as well as high-pressure irrigation, which can be performed with a pressurized fluid bag or a large syringe with an 18-gauge catheter.^6,7 For suturing more superficial wounds that have been cleaned, a veterinarian should perform the procedure.

Eld’s 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.⁸

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