Chemical Immobilization of White-Tailed Deer

White-tailed deer (Odocoileus virginianus) are the smallest members of the North American deer family, and are found from southern Canada to South America. Favoring wooded areas, the home range of a White-tailed deer is usually less than one square mile. Typically, deer collect in family groups of a mother and her fawns. When a doe has no fawns, she is usually solitary. Male bucks may live in groups consisting of three or four individuals, except in mating season, when they remain solitary.¹

The White-tailed deer is an herbivore that usually follows well-used trails to its feeding areas, and feeds in the early morning hours and in the late afternoon.² A deer's diet changes depending on its habitat and the season. White-tailed deer eat green plants in the Spring and Summer. In the fall, they eat corn, acorns and other nuts. In the winter, they eat the buds and twigs of woody plants. Usually mating in November in the northern parts of their range and in January or February in the southern parts of their range, females have one to three fawns about six months after mating.¹ Fawns are reddish-brown at birth with white spots that help camouflage them. They can walk at birth and forage for food a couple of days later, and are weaned at about six weeks of age.

The White-tailed Deer mother leaves her fawns well-hidden for hours at a time while she feeds. If she has more than one fawn, she will often hide them in separate places. While they are waiting for their mother to return, the fawns lay on the ground with their heads and necks stretched out flat on the ground, which makes it more difficult for predators to find them.¹ Female fawns may stay with their mother for two years, with young males leaving after a year.

Human Habitats and Deer Management

In some areas, deer overpopulation is a problem. While wolves and mountain lions used to be the chief predators of white-tailed deer and helped keep their population under control, due to hunting and human development there are far fewer wolves and mountain lions left in most regions of North America.¹ Without these natural predators, deer populations can sometimes grow too large for their environment and deer can starve to death. In rural areas, hunters help control deer populations, but in suburban and urban areas, hunting is typically not allowed and deer populations can grow out of control.

Other factors can affect deer populations. Disease and parasites like lice, mites and roundworms can weaken or kill deer. Young deer and old deer often get sick and die, especially in Winter, which can be a dangerous time for deer. Their long narrow legs and pointed hooves make it hard for them to move in snow and ice and it is easier for predators to catch them.¹

Today, White-tailed deer and humans are living closer to each other because of human development and growth in deer and human populations. Because humans and deer often share a habitat, this can give rise to problems for both. When a deer's habitat becomes smaller because of human development, deer will often eat food from gardens. Deer need to cross roads to look for food and water and are often struck by cars. Humans can also contract Lyme Disease from the deer tick, which poses a public safety risk.

Chemical Immobilization of White-Tailed Deer

Thus, White-tailed deer management often requires that animals be immobilized for capture, handling, or transport.³Many wildlife immobilization techniques exist, including chemical immobilization with remotely delivered anesthetic agents. The most suitable immobilizing agents should be easy to administer, have a high therapeutic index, require only small volumes for remote delivery, provide short induction times, be reversible, and exhibit no long-term effects.⁴Currently however, few drug combinations meet these criteria for White-tailed deer.

Since the refinement of modern chemical immobilization techniques for wildlife began in the 1950s, the related drug protocols have undergone many changes and improvements. Since single agent drugs rarely provide the ideal combinations of smooth, rapid induction, recovery and other factors, drug combinations are in ongoing development in the field of chemical immobilization of wildlife.

Some wildlife veterinarians and managers have widely employed the combination of the traditional agents xylazine and telazol, antagonized with tolazoline for the immobilization of White-tailed deer. Quite often, animals exhibit significantly longer and more variable induction and reversal times than desired using this combination.^2,4

Custom Compounds for Chemical Immobilization

More recently, the combination of medetomidine and ketamine (M/K), antagonized with atipamezole has come into use. MK is available from veterinary custom compounding pharmacies as a premixed formulation that was developed to provide veterinarians and wildlife handlers with a field-tested immobilization anesthesia option that can be effectively used to immobilize a broad range of exotic animal species. Medetomidine provides superior pain relief and muscle relaxation to other compounds employing α-2 adrenergic agonists, while ketamine supplies an effective paralytic.⁵ In combination, the two provide safe, smooth induction times and excellent recovery results. It is important to understand however, that the level of anesthesia being administered with MK is a deep sedation, not to be confused with other sedations that are moderate.

For White-tailed deer, the preferred route for the administration of MK by remote delivery is via intramuscular injection. The aim is to hit the animal in a specifically-selected site, causing injection into vascular tissue and facilitating rapid absorption of the drug. Not all areas of an animal's body are equally well-suited for injection by remote delivery; thus, the injection site should be carefully chosen.

The neck is generally a suitable site for large animals with muscular necks, such as deer. Care should be taken to avoid hitting the jugular vein, the upper neck and the head. The ideal injection site is the trapezius muscle mass at the upper base of the neck. This injection site is also suitable for species such as elk, moose, buffalo, bear, the equids and larger antelopes, rhinoceros, hippopotamus and elephant (if the ears can be avoided). Animals with slender necks, such as gazelle, gerenuk, giraffe and impala should not be darted in this area.⁴

As mentioned above, atipamezole is the ideal reversal agent for the MK formulation. This is also available in kit form(with the medetomidine/ketamine formulation) from some veterinary custom compounding pharmacies in the appropriate concentration. Atipamezole is an α2-adrenergic antagonist that competitively inhibits α2-adrenergic receptors, thereby acting as a reversal agent for α2-adrenergic agonists such as dexmedetomidine and medetomidine. Atipamezole reduces sedation, decreases blood pressure, increases heart and respiratory rates, and reduces the analgesic effects of α2-adrenergic agonists.⁵

NexGen Pharmaceuticals is a veterinary compounding pharmacy that offers a variety of specialized MK formulations and kits that are ideal for the chemical immobilization of White-tailed deer. Their MK Kit covers a broad range of field work and sedation applications and offers a smooth induction and quick recovery times. This kit is recommended for fawns and smaller does.

Each MK Kit contains:

Vial 1 (30mL) - Medetomidine HCl 5mg/mL + Ketamine HCl 150 mg/mL

Vial 2 (30mL) - Atipamezole HCl 20 mg/mL (Medetomidine Reversal - 1mL Atipamezole to Every 1mL MK)

NexGen’s MK2 Kit provides longer and deeper sedation, an extended working time and quick recovery. This formulation is recommended for larger-bodied deer and bucks, and for scenarios where longer working times and/or multiple procedures are required. Caution should be taken when ambient air temperature exceeds 82 degrees Fahrenheit, as there is a high risk of hyperthermia if the animal gets too hot while under sedation.

Induction Time: 8 - 9 Minutes
Working Time: 60+ Minutes
Reversal/Recovery Time: 8 - 9 Minutes

Each MK2 Kit contains:

Vial 1 (30mL) - Medetomidine HCl 10 mg/mL + Ketamine HCl 200 mg/mL

Vial 2 (30mL) - Atipamezole HCl 20 mg/mL (Medetomidine Reversal - 2mL Atipamezole to Every 1mL MK2)

Finally, the MKB Kit by NexGen is intended for fast and smooth induction due to a lower ketamine concentration and faster reversal times. Here, a benefit of using these sedations is the ability for the animal to recover on its own if the handler does happen to lose the animal after darting it. This kit is recommended for free-range capture scenarios where there is a risk of losing the animal post-injection.

Induction Time: 3 - 5 Minutes
Working Time: 10 - 15 Minutes
Reversal Time: 5 -9 Minutes; Standing 15 Minutes

Each MKB Kit contains:

Vial 1 (10mL) - Medetomidine HCl 10mg/mL + Ketamine HCl 50 mg/mL + Butorphanol Tartrate 25 mg/mL)

Vial 2 (30mL) - Atipamezole HCl 20 mg/mL (Medetomidine Reversal - 2mL Atipamezole to Every 1mL MKB)

Vial 3 (10mL) - Naltrexone HCl 25 mg/mL (Butorphanol Reversal - 1mL to Every 1mL MKB)

¹animaldiversity.org.

²VP Walsh & PR Wilson (2002) Sedation and chemical restraint of deer, New Zealand Veterinary Journal, 50:6, 228-236, DOI: 10.1080/00480169.2002.36318.

³Monteith, K., et. al. Immobilization of White-Tailed Deer With Telazol, Ketamine, and Xylazine, and Evaluation of Antagonists. The Journal of Wildlife Management 76(7):1412–1419; 2012.

⁴Kreeger T., et. al. Handbook of Wildlife Chemical Immobilization, 3rd ed. Wheatland, WY, 2007.

⁵Plumb’s Veterinary Drugs.

About NexGen Pharmaceuticals

NexGen Pharmaceuticals is an industry-leading veterinary compounding pharmacy, offering sterile and non-sterile compounding services nationwide. Unlike other veterinary compounding pharmacies, NexGen focuses on drugs that are difficult to find or are no longer available due to manufacturer discontinuance or have yet to be offered commercially for veterinary applications, but which still serve a critical need for our customers. We also specialize in wildlife pharmaceuticals, including sedatives and their antagonists, offering many unique options to serve a wide array of zoo animal and wildlife immobilization and anesthesia requirements.

Our pharmacists are also encouraged to develop strong working relationships with our veterinarians in order to better care for veterinary patients. Such relationships foster an ever-increasing knowledge base upon which pharmacists and veterinarians can draw, making both significantly more effective in their professional roles.

Disclaimer

The information contained in this blog post is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the medications shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular medication. You should consult your veterinarian about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the medications to diagnose, cure or prevent disease. Medications compounded by NexGen Pharmaceuticals are prepared at the direction of a veterinarian. NexGen Pharmaceuticals compounded veterinary preparations are not intended for use in food and food-producing animals.

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