How To Evaluate Which Wildlife Drug Combination to Use

by | May 20, 2021

Dr. Mark describes creating new drug combinations for immobilizing lynx

Note: This blog article is a bit technical but it covers the basics for how to choose an immobilizing drug combination for a wildlife research or management program.

To learn more, register for The Foundations of Wildlife Chemical Capture which covers in detail the immobilizing drugs, drug delivery systems, drug dose calculations, and animal care.

As project veterinarian for a Colville Tribe lynx translocation program I’m recommending drug combinations for the project that possibly have not been used in lynx before.

I‘m not satisfied with the previous drug combinations that have been used for lynx. I want what is best for the animal and safe for the biologist. To come up with these new drug combinations, I utilized my 30+ years of experience as a wildlife veterinarian and the latest tools and practices.

canadian lynx

Developing a new drug combination required me to consider:

How practical is the drug combination for the biologists? They will be capturing lynx in harsh winter conditions.

  • Do they have to draw each drug up or will it be pre-mixed?
  • Do they have to calculate drug doses or can they follow an easy chart?
  • Are the volumes easy to work with and will the volumes be suitable for the drug delivery system they choose to use?
  • How long do the drug combinations cause the animal to be down for and how long do the biologists have to remain in the field?
Radio collaring a lynx in Alaska

How does each drug combination affect the animal?

  • Does it produce a strong anesthesia (unresponsiveness) so it is safe for the biologists?
  • Does it produce a safe anesthesia for the animal where temperature, pulse, and respiration values are within healthy ranges in this extreme weather?
  • Does it produce a short or long downtime?
  • Is the drug combination reversible so the biologist can wake the animal up as soon as processing is done or when there is a serious concern for how the animal is doing?
  • Is the recovery relatively smooth and easy for the animal?

So here’s what I came up with:

BAM and Ketamine

The drug combination BAM (Butorphanol, Azaperone, and Medetomidine) sold by Zoo Pharm is an exceptionally versatile drug for many different species. With small volumes, it produces a relatively quick induction (this is the time from drugging the animal to when they can be handled), a steady relaxed anesthesia, and BAM can be reversed at any time to produce a smooth and rapid wake up and full recovery. But not for lynx, bobcats, or there felids.

With lynx and bobcats (and other felids), BAM does not always produce a reliable anesthesia. Cats can suddenly wake up and biologists have been scratched and bitten.

One approach to produce a more reliable knockdown and safe anesthesia is to add a little ketamine. If there is too much ketamine, the animal wakes up with a horrible recovery that is tense and disorienting. But a small amount, i.e. a quarter dose, can improve BAM drug effects. One mountain lion project has had great success with BAM/Ket combination. See our previous blog article about a new drug combination for cougars by guest author, Bart George.

(There are great videos of tense ketamine effects in fisher and the smooth, quick recovery of BAM in a mountain lion in my Foundations chemical capture course.)

I have decided to recommend a low BAM dose for lynx, O.2 ml with 1/4th the ketamine dosage for lynx in a ketamine/xylazine drug combination. Please note that I am not providing the final doses or dosages because it has not yet been tested. This blog article is about the process of developing a drug combination for wildlife.

I am going to recommend two different drug combinations and determine which combination is safer for the lynx and most practical for the biologist. Here is the second drug combination.

Ketamine/Medetomidine with Butorphanol

A commonly used drug combination for lynx and bobcats is ketamine (an anesthetic) and medetomidine (a strong sedative). The drug combination is sold as a kit from Zoo Pharm. The shortcoming of this drug combination is that it often produces undesirable ketamine effects during recovery so the animal is tense, agitated, hypersensitive to stimulus, disoriented, and often struggling to stand or sit up.

Another shortcoming to this drug combination is that felids can occasionally wake up leading to human safety risks.

Vial of butorphanol

One of the best ways to cover up the ketamine effects and improve the reliability of the sedative is to add butorphanol (i.e. Torbugesic®) to enhance the medetomidine effects. It is widely recognized around the world (but less commonly in the US) that butorphanol will act synergistically to enhance the qualities of medetomidine (calm, quiet, relaxed), reduce the amount of ketamine needed, and overcome or coverup the negative ketamine effects. Adding butorphanol will keep the animal down, quiet, and relaxed until the ketamine is metabolized.

So, I am also recommending a ketamine/medetomidine/butorphanol drug combination for the lynx translocation program.

How Can We Evaluate Which Drug Combination to Use?

How can we determine if either or both drug combinations are safe and effective? How do we decide which to use?

  • We first carefully drug captive lynx in a controlled setting and continually monitor and document TPRs (temperature, pulse, and respiration) in addition to color of the gums and CRT (capillary refill time). There are great videos in the Foundations course showing how to monitor these vital signs.
  • We assess the “quality” of the anesthesia.
    • Does the drug combination produce a short or long down time?
    • Is it reversible or not reversible?
    • Are there good working periods of anesthesia when the animal is calm and unresponsive?
    • Is the animal tense or relaxed? Does the animal’s body move very little or is there a lot of twitching and movement (i.e. ketamine effects)?
    • Do the TPRs typically stay within healthy ranges?
    • How quickly can the animal recover with its head up and standing? How smooth and relaxed is the animal’s recovery?

We are going to look for programs with captive lynx who will test these drug combinations when they have a need to immobilize the animals. If/when we feel these drug combinations are safe, then we will ask the biologists to try these drug combinations with lynx in the field and be just as diligent with their patient monitoring and record keeping. There will be a post-capture assessment with every animal and we will continually evaluate our drug combinations and other protocols to produce the most effective chemical immobilizations that are safe for both people and animals.

Learn more about wildlife immobilizing drug combinations in my online course, “The Foundations of Wildlife Chemical Capture”.

If you are wildlife student who is knew to the profession, the Foundations course will give you a full understanding of how to conduct chemical captures with success and confidence. I offer a student discount for those enrolled in college.  Just contact me at [email protected] for a Student Discount Coupon.

If you are a seasoned professional the Foundations course will surprise you with practical field-based tools and techniques that will strengthen and improve your chemical captures.

Mark R. Johnson, DVM

Meet Mark R. Johnson, DVM

Wildlife Veterinarian, Instructor, and CEO of Global Wildlife Resources


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