Every so often, a story appears in the press about an animal found alive after a (failed) euthanasia procedure. These reports are often disturbing, as the companion animal-usually a dog-is commonly discovered in the cold-storage unit of the facility where the procedure took place. This brings to mind images of being trapped in a freezer, suffering unimaginably, wondering what new torment will come next. How can this happen?
To answer the question, it is necessary to give an explanation of how most euthanasias are performed. Currently, the vast majority of euthanasia is done via injection. A quantity of a rapid-onset barbiturate, usually pentobarbital, is administered intravenously, resulting in the cessation of heart function. Occasionally, the solution is given in the abdominal (intraparitoneal) cavity where it is absorbed gradually through the tissue surrounding the stomach and other organs.Both of these methods are predominantly painless outside of the initial stick from the needle.
Barbiturates are a class of drugs that increase the inhibitory function of the body’s nervous system. This means that the drug slows down the signals the brain sends to the rest of the body, such as the signals that tell the heart to beat. Given in sufficient doses, the signal shuts off completely. A sufficient dose is critical.
There are many ways to make a determination of death and confirm that euthanasia is successful. The only way to be sure is to wait for the remains to become rigid, the process called rigor mortis. This can take anywhere from 2 to 12 hours, and most facilities that perform euthanasia are not able to devote this amount of time to observation. In addition, many facilities euthanize at the end of the day for both pragmatic/logistical and psychological reasons.
Other methods include checking for breathing, heartbeat, and eye reflex (blink response). Finally, a check can be made for a deep pain response (a reflex, not an experienced pain) or a needle may be inserted into the heart muscle to observe any contraction. These final procedures are typically only performed after there are no signs of consciousness for some time. When an intracardiac insertion is performed, no solution is administered unless there is indication of heartbeat and all other tests have confirmed unconsciousness. An intracardiac injection to a conscious animal is very painful, and is illegal in some states.
All of these methods take time, something that is often in short supply where euthanasia is frequent. This is no excuse, however, for not making a diligent check for death. In most cases, though, these procedures clearly establish successful euthanasia, and the post-euthanasia exam is routine. So with all these safeguards, how do mistakes still happen?
The final answer is a combination of human error and the nature of the drug itself. A certain degree of skill is necessary to perform all of the checks described. Euthanasia technicians, and even veterinarians, vary in their abilities to perform these checks. Added to this, barbiturates can slow function to such a degree that heartbeats may be nearly imperceptible. Barbiturates inhibit signals to the body rapidly, but this onset is still in some sense gradual. In certain cases, heartbeats may only occur once or twice every few minutes. When the heart does beat, it is often unenergetically, and very quietly. This can give an appearance of death known to fool many professionals, thus the long list of safeguards. Yet there is no doubt that in a case of failed euthanasia, someone concluded that all biological function had stopped, and were tragically mistaken.
Recovery from this experience is very prolonged. Such a deep state of unconsciousness, one that imitates death, lasts many, many hours. While not impossible, it is exceedingly unlikely that any conscious suffering occurs in a euthanasia survivor. Conscious experience requires rapid communication in the nervous system, and this is only possible hours, sometimes days, after a large dose of barbiturates.
Euthanasia survival is exceptionally rare. While there are no statistics on the phenomenon, this can be asserted with confidence simply because of the nature of the drug. Barbiturates are a powerful substance and are administered in humans with great care. In euthanasia, they are given many thousands of times the dose that would be prescribed for any conceivable therapy. At such high quantities and concentrations, cases of survival are extraordinary. That we see them occasionally speaks not only to the need for qualified personnel to conduct euthanasia. It also demonstrates that for such an atypical incidence to emerge, even rarely, a dreadfully high number of euthanasias are completed. Sadly, pet overpopulation has made this the case.