Wild Cat Offers Lessons on Taming Anesthesia Risks

Image: Arizona Game and Fish Department

“Macho B,” who a week ago became first Arizona jaguar to be captured and fitted with a tracking collar, was euthanized on March 2nd as a result of illness according to an Arizona Game and Fish media release. Biologists tracking the big cat became concerned about his health when the jaguar’s activity level decreased. He was re-captured and transported to the Phoenix Zoo for care and testing. Tests at the zoo revealed kidney failure, which is common in aging cats, and Macho B was euthanized due to a poor prognosis after he failed to respond to treatment.

While Macho B’s death is a tragic setback for jaguar research in Arizona, this event reminded me and Dr. Burns of why we have set our personal standard of care so high when it comes to anesthesia. Macho B was a special cat; he’d been photographed by trail cameras on numerous occasions over more than a decade and was well known to those researching borderlands jaguars. Our patients are special, too, and at PPH we do all we can to minimize the risks of general anesthesia.Biologists and wildlife veterinarians are limited in what they can do to ensure that a 120-pound jaguar can be anesthetized as safely as possible. Fortunately, we don’t have those same limitations with pets.

When a veterinarian is aware of pre-existing health problems, anesthesia can be safely performed in almost any patient by carefully choosing drugs for that individual, providing proper supportive care, and monitoring each patient both during and after anesthesia.PPH performs pre-anesthetic lab tests on every patient undergoing general anesthesia. Although Macho B was probably in the early stages of kidney failure before he was caught and anesthetized for examination and the placement of the tracking collar, neither biologists nor veterinarians could have known this from just looking at him. The anesthetic agents used, while safe in healthy wild cats, likely caused a drop in blood pressure that resulted in additional injury that his kidneys simply couldn’t compensate for.

When we’re aware of unseen medical problems, we can adjust our choice of anesthetic agents to reduce the stress placed on compromised organs. PPH stocks and uses several different anesthetic agents for precisely this reason.Like most wild and zoo animals undergoing anesthesia, Macho B probably received just one or two anesthetic drugs. While easy to administer, so-called “single agent anesthesia” virtually guarantees that relatively high doses of this agent must be used to achieve the desired effect. The use of multiple drugs (“balanced anesthesia”) tailored to each patient allows a veterinarian to minimize the side effects of each individual drug, resulting in a safer overall anesthetic event. That’s why PPH starts with a dose of sedatives and pain relievers for nearly all anesthetic cases. This sedation and pain relief allows us to use smaller doses of the stronger general anesthetic agents and minimize the side effects that are an unavoidable part of any anesthetic.

While biologists were likely observing Macho B’s heart rate and breathing, it would be nearly impossible to monitor other important vital signs, such as blood pressure, exhaled carbon dioxide, and blood oxygen saturation under field conditions. Monitoring of anesthetic cases at PPH starts with a direct observation by a living, breathing, well-trained, and experienced veterinary technician whose sole responsibility is monitoring the patient’s health. At her fingertips is monitoring equipment that tracks blood pressure, carbon dioxide, blood oxygen levels, ECG/heart rate, and body temperature. This level of monitoring helps us detect even minor changes in the patient and respond appropriately before a problem arises.

That’s the key to safety, really: preventing minor concerns from becoming serious problems. And that’s why PPH provides care such as IV fluids and temperature support for every anesthetic patient. With very rare exceptions, our patients’ response to anesthesia is predictable. Anesthetic drugs decrease heart rate, respiratory rate, and blood pressure. Breathing gas anesthetics carried by cold, compressed oxygen cools the patient. Supportive care such IV fluids and warming devices help offset changes we should already be expecting. In the rare event of an emergency, the IV catheter is our “lifeline” for the administration of potentially life-saving drugs.

Finally, while Macho B was on his own once he began to stir after anesthesia, direct monitoring continues well beyond that point at PPH. A veterinarian or technician is at each pet’s side until their protective swallowing reflex returns after anesthesia, and they are housed in a warm, dimly-lit hospital ward that’s clearly visible from all areas of our treatment room until fully recovered and ready to go home.

General anesthesia carries risks. Though it’s a special case, Macho B’s story is a sad reminder of that fact. The good news is that we can minimize anesthetic risks in pets by fully evaluating their health prior to anesthesia and using this information to carefully plan balanced anesthesia for each individual patient. Once anesthetized, PPH’s patients are directly observed by a trained staff member and the most important vital signs are monitored using state-of-the-art equipment. After anesthesia, all patients are in plain sight from our treatment area and under observation until they go home. Helping our patients “snooze” safely and soundly through procedures requiring general anesthesia allows our entire team to sleep better at night. We hope it does the same for you.

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