MKM Kit Dosages & Usages
Chemical sedation and anesthesia are integral parts of veterinary medicine in the zoo setting. Even the most basic clinical examinations require sedation or anesthesia, since most patients in the zoo are either too nervous, too fast or too dangerous to examine without chemical immobilization. Most of the medications and equipment are familiar to veterinarians and animal handlers from domestic animal or human medicine, but often new combinations of medications or modifications to existing equipment will be essential.1
Before attempting to anesthetize an unfamiliar species, the zoo veterinarian will consider any anatomic or physiologic adaptations that might influence the anesthetic event.1 Then, the level of anesthesia required for the procedure should be considered. The vast majority of procedures performed in zoological settings are for loading, crating, or simple clinical exams, and for this a much lighter level of anesthesia may be used than for a surgical procedure. Very occasionally, chemical immobilization is required in zoos in instances of escaped animals. In these applications, drugs or drug formulations with fast induction are essential, but the recovery (with or without reversal agents) should be as safe and gentle as in the field or elsewhere.
Similarly, the likely duration of the procedure and the need for and possibility of prolonging the anesthesia should be considered.2 Logistics are important, particularly with heavy animals, and sufficient crates, ropes, machinery, and human power should be readily available, as should all equipment needed for the procedure as to avoid unnecessarily prolonging down time. An important part of planning is to inform the veterinarian’s support staff of what is going to happen and what is expected of them. Additional factors to be considered are climatic conditions and the demeanor of the patient.
Safety and Liability
Zoos have ethical as well as legal obligations to provide the requisite husbandry, medical treatment and nutritional programs for the animals in their care. Zoos in the United States are required by law to engage an attending veterinarian to provide veterinary care for the animal residents, and to assure that at least minimal standards of veterinary care are in place. These minimal standards have been set according to the Animal Welfare Act of 1966 and the subsequent amendments that are enforced by the United States Department of Agriculture (USDA).3 Maintaining standards of veterinary care requires professional oversight of all related facilities, including the supervision of the veterinary medical program by a licensed veterinarian with experience in exotic animal medicine.
The zoo’s attending veterinarian is typically involved in the overall management of zoo animals, including behavior, husbandry, nutrition, reproduction, exhibit design, and conservation programs. In the U.S., the Animal Welfare Act states that “Each zoo and aquarium shall assure that the attending veterinarian has appropriate authority to ensure the provision of adequate veterinary care and to oversee the adequacy of other aspects of animal care and use” (Animal Welfare Act, Title 9, Part 2.40). This being the case, the veterinarian is to a large extent responsible for the design, implementation, and maintenance of the veterinary care program for the zoo.
Any additional staff needed to support veterinary medical care programs will be predicated upon the size of the institution, the physical facilities, the number of animals, and the level of difficulty involved in maintaining resident species. Both professional and supporting personnel are essential in implementing those aspects of the veterinary medical program concerned with veterinary medical care. Zoos have been mandated to provide full administrative, technical and husbandry support for the zoo’s veterinary medical programs, with one full-time staff member at the institution being responsible for the medical care program.3 Establishing protocols for safely subduing animals that escape their enclosures falls within the parameters of these mandates.
The MKM Formulation for Exotic Animals
A wide variety of compounds are used to immobilize wildlife and exotic animals. In recent years, medetomidine/ketamine (MK)-based formulations have gained popularity among wildlife veterinarians and those practicing in the zoo setting. At the time of this writing, MK-based formulations have been used to successfully immobilize many exotic species, including large cervids and carnivores.
The MKM formulation by NexGen Pharmaceuticals is a premixed formulation 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. Also known as the “Escape Kit,” the MKM Kit is often used in zoos when an animal escapes from its enclosure. It has been used successfully on large carnivores (big cats, etc.), but is also good for routine doctoring.
Medetomidine (medetomidine hydrochloride) is a synthetic α-2-adrenoreceptor agonist with sedative and analgesic properties. Medetomidine is used by veterinarians as both a surgical anesthetic and analgesic. The pharmacological restraint and pain relief provided by medetomidine facilitates handling and aids in the conduct of diagnostic or therapeutic procedures. It also facilitates minor surgical procedures (with or without local anesthesia) and dental care where intubation is not required.
The pharmacologic effects of medetomidine include depression of CNS (sedation, anxiolysis), GI (decreased secretions, varying effects on intestinal muscle tone) and endocrine functions, peripheral and cardiac vasoconstriction, bradycardia, respiratory depression, diuresis, hypothermia, analgesia (somatic and visceral), muscle relaxation (but not enough for intubation), and blanched or cyanotic mucous membranes. Effects on blood pressure are variable, but medetomidine can cause hypertension longer than does xylazine. Medetomidine also induces sedation for a longer period than does xylazine. Sedative effects persist longer than analgesic effects.4
Ketamine is a fast-acting dissociative anesthetic that is often used in combination with a tranquilizer-sedative, usually a benzodiazepine or an α-2 agonist. Immobilizations with combinations including ketamine provide a rapid onset of action, immobilization within 10 min, and long duration (up to 2 hours). Ketamine provides excellent somatic analgesia, but poor visceral analgesia, and therefore it should not be used as the sole analgesic for procedures expected to cause visceral pain. When used alone, side effects include increased muscle tone, hyperthermia, excessive salivation, catecholamine release, and convulsions. Ketamine has no known antagonist; for this reason the use of a reversible drug in combination with ketamine for field immobilizations is commonly recommended.4
Midazolam has been used in veterinary patients principally for its sedative, anxiolytic, and muscle relaxant properties as a premedication (combined with other drugs) prior to induction of general anesthesia. When midazolam is used alone, sedation may be adequate in ruminants, camelids, rabbits, ferrets, and some birds; it does not appear to provide predictable sedation in dogs, cats, or horses as they may become sedated or dysphoric and excited. Cats may be more prone to developing an excited effect/disinhibition as compared with dogs.4
When used in combination with other drugs (eg, opioids, ketamine, acepromazine, dexmedetomidine), midazolam provides more reliable sedation. Midazolam used in place of diazepam as a premedication should be administered mg/mg for diazepam in the protocol. Midazolam IV, IM, or intranasal (but not per rectum) may be used to treat status epilepticus.4,5
The MKM formulation consists of medetomidine (3.3mg/ml), which provides superior pain relief and muscle relaxation to other compounds employing α-2 adrenergic agonists, ketamine HCL (150 mg/ml), which supplies an effective paralytic and midazolam (5mg/ml), for its superior muscle relaxant properties. In combination, these three agents provide a fast, safe induction and excellent recovery.
For those new to utilizing NexGen’s MK formulations to manage wildlife and exotics, it is important to understand the level of anesthesia provided with medetomidine/ketamine sedation. It is a deep sedation, not to be confused with other sedations that are moderate. For NexGen’s MKM formulation, reversal agents will be required. The MKM Kit includes the MKM formulation with accompanying reversal agents (and a manufacturer discount for purchasing the two in combination).
1Bertelsen, M. Anesthesia - The Tall and the Small, One Size Does Not Fit All. In: Proceedings NAVC Conference 2013 Small Animal.
2Nielsen, L. Chemical Immobilization of Wild and Exotic Animals. Iowa State University Press, 1999.
3Carpenter, N., et. al. Guidelines For Zoo and Aquarium Veterinary Medical Programs and Veterinary Hospitals, 6th Edition. In: American Association of Zoo Veterinarians 2016.
4Plumb’s Veterinary Drugs.
5Chinnadurai, Sathya & Strahl-Heldreth, Danielle & Fiorello, Christine & Harms, Craig. (2016). Best-practice guidelines for field-based surgery and anesthesia of free-ranging wildlife. I. Anesthesia and analgesia. Journal of wildlife diseases. 52. S14-S27. 10.7589/52.2S.S14.
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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