Anesthesia Death


Anesthesia death and reactions

Question: Dr. Richards, I sold some people a puppy with a neuter contract and they had him neutered at about 6 month. He was a small Bichon. He had an allergic reaction to the anesthetia, according to the post, and died. Every vet that I have asked said that there is no way to predict or test for this. Would it make any difference if they had waited until he was older? Is there no way to test for this? They have just bought another puppy and
obviously want to avoid this happening again. We are both very leary of having surgery. Carol

Answer: Carol-

It is very hard to predict reactions to anesthesia. The anesthetic death rate in pets is higher than in humans, almost certainly because we do not have dedicated anesthetists in the surgery room during veterinary surgeries, in most cases. It is more difficult to accurately monitor blood pressure in pets than it is in humans and blood pressure is probably the earliest indicator of problems with anesthesia in many patients. Due to this difficulty in monitoring, though, it is not common practice for blood pressure to be monitored in pets. Pulse oximetry is used to monitor surgery by many veterinarians and while this is a good practice, it doesn't always
allow early recognition of trouble. Continuous monitoring of patient temperature is also helpful and is often available. It is unusual for surgical anesthesia to be monitored by a another veterinarian and extremely unusual for a practice to have a board certified anesthesiologist monitoring patients. So when a crisis occurs, the veterinarian doing the surgery suddenly becomes both the surgeon and the anesthetist, with crises in both areas. This results in an inability to do a really good job dealing with either the surgery or the anesthesia --- and the result is that veterinary patients have a higher death rate from anesthesia. This is not an allergy to anesthesia, nor is it even a particular sensitivity, in many cases. Something unforeseen happens, such as a slight sensitivity to anesthesia, or a drop in blood pressure due to surgical manipulations, or surgical blood loss --- and a downward spiral in patient stability results. In many instances in veterinary surgery the first visible sign of this is cardiac or respiratory arrest, since there is no one monitoring the patient to pick up on the more subtle signs that occur earlier. Cardiac or respiratory arrest is a bad point to be starting the process of dealing with the problem. It is the inability of our profession to provide dedicated anesthesiologists, primarily due to cost factors, that leads to this problem. The end result is that in the only big study I know of examining anesthetic risk, the anesthetic death rate in pets was about 1 in 400. In humans, the anesthetic death rate is lower but the cost of surgery is dramatically higher, due in part to having a dedicated anesthetist.

So what can a pet owner do? We have an odd circumstance at our practice, in that my wife and I run a practice together that could be run by one veterinarian. So we have the luxury of having a veterinarian on hand to
monitor anesthesia during surgery. I believe that this has helped our anesthetic success immeasurably. Only one client in the entire time I have been in practice has asked me to provide an anesthesiology specialist. We were not able to comply with that request but we were able to offer the services of a second veterinarian to act as anesthetist, an option that many practices could probably provide if the request was made. It would cost extra but I think the expense would be worthwhile. Prior to the time my wife graduated from veterinary school we had two very good certified veterinary technicians who monitored our surgeries. This worked well, too --- but the technician has to be dedicated to the anesthetic procedure for best success. It is reasonable to ask for this type of care as long as you are willing to pay for the services of the second veterinarian or the technician, if the cost is not already factored in to the surgery and anesthesia (as it is in our practice).

So while I know that there are some patients who are just sensitive to anesthesia and may get into trouble, including dying, despite the best efforts of the attending veterinarian(s), there is also no doubt that many anesthetic deaths in pets could be avoided if the standard of care included dedicated anesthesiologists who were monitoring patients closely enough to identify problem situations before they became crisis situations. Since this isn't standard practice, you have to ask for this sort of service if you want it --- and you have to be willing to pay extra to get it.

Evaluation of blood chemistry values and blood cell counts prior to surgery may help to avoid anesthetic problems in a small number of pets. Many times pets that have anesthetic problems have normal lab values prior to surgery, though.

Size is a factor in anesthetic deaths, primarily because it is easier to chill a smaller patient during surgery and because the smaller the patient, the more critical minor variations in measuring anesthetics becomes. I am not sure if waiting several months in a small breed dog would make all that much difference since the patient would still be small, though. There appear to be no significant survival advantages, from an anesthetic standpoint, between surgery at four to six months and older, based on studies of early spay and neuter procedures.

Once a client experiences an anesthetic death, it can be very hard to convince them that anesthesia is usually successful, for obvious reasons. 1 in 400 odds are pretty good, but this can be improved upon and if enough clients are willing to pay extra to have better odds, it will be improved upon.

Mike Richards, DVM

Anesthesia Death

Q: I brought my 1 1/2 year old male chihuahua to my vet last Saturday for a castration. I did not know that he was supposed to go without food or water from 8:00 PM the evening before. I brought him into the office early the next day. When they asked me that question (whether he had food or water) I answered honestly and offered to bring the dog back the next day. They told me that it wasn't necessary and took the dog anyway. They told me to come back the next day to pick him up. They next day, when I went to pick him up, they told me he had died while they were preparing him for surgery. The Dr. told me that he went into cardiac arrest. The surgery was never performed because he died first. When I noted the time on his chart, it indicated that surgery was attempted shortly after we left him there. This was not what I understood was going to happen. I am naturally bitter over this, especially since there was no attempt to contact me when it happened and the fact that he was operated on so shortly after we left him there. The dog was in perfect health (he has flown to Paris France from Los Angeles). We just got a health certificate for him from the same vet 1 1/2 months ago. What I want to know is, have veterinarians been taken to litigation for malpractice? How frequently do dogs die undergoing surgery for castration? I'm considering bringing this veterinarian to court if it's possible. I just want to make sure that this doesn't happen to someone else. I feel that my pet died of either fright or an overdose of anesthesia. Either one of these causes was totally preventable in my opinion. Thanks a lot. Joe in Riverside CA

A: Joe- I am sorry to hear of the loss of your Chihuahua. There is a broad range of possible problems leading to the death of a young pet when anesthesia is induced. Some of these problems are hidden and are very difficult to detect in advance of anesthesia. However, there is the possibility of a mistake made during administration of anesthesia whenever an death occurs in conjunction with anesthetic use.

No one that I know of keeps any form of accurate statistics on the percentage of surgical or anesthetic deaths in veterinary medicine. This is unfortunate, because anesthetic protocols vary widely in veterinary medicine, partly due to the lack of good statistics about which anesthetic combinations work best. It is very hard to even guess at mortality rates since there are so many potential anesthetic combinations. In addition, some of the "safer" anesthetic combinations as judged from the standpoint of whether the patient lives or dies are highly suspect as far as analgesia goes. Meaning that they may not provide as much pain relief as we might want when doing surgery. This is always a trade-off but the ideal anesthetic would provide complete long lasting pain relief during and immediately after surgery and still be very safe during surgery. At present, there is not an agent that I know of that produces both very safe anesthesia and very potent analgesia. Some vets opt for more analgesia and some for less risk of death.

I do not believe in withholding water from patients prior to surgery other than the time they spend in our hospital immediately prior to surgery. I suspect that withholding water may cause more problems than it prevents but do not have any proof of this, either. The importance of withholding food varies according to the anesthetics used, as well. We do recommend not feeding patients prior to routine surgeries. However, we do a lot of emergency surgery and many of these patients have eaten shortly prior to surgery. So far this has not caused significant problems in our practice. I can not remember an anesthetic death related to vomiting in the surgical or post-surgical period.

With all of this said, there is still room for questioning the cause of the death of your pet. This is natural and you should be able to discuss it with your vet. The best option is to ask for a time to discuss the anesthestic and surgical procedures and review what happened. This can be hard for owners even when the relationship with their veterinarian is very good. It is often the best path to real resolution of the concerns owners have, though. Since there does seem to have been some communication lapse with your vet you may need to pursue this through a third party. In general, I think it makes more sense to contact the veterinary board in your state than a lawyer. They have the expertise to review the case and detect problems in procedure and they have a means for disciplining a veterinarian if necessary. They may conclude that there were no preventable problems which would hopefully help to set your mind at ease, as well. You do have the right to contact a lawyer and pursue a lawsuit. Veterinarians are sued for malpractice over the loss of pets and livestock. I am not a lawyer but it is my impression that in most states you can only sue for the actual value of the pet which does limit the impact of a lawsuit on a veterinarian since most pets have fairly low purchase prices.

You are correct that fright contributes significantly to the risk of anesthetic death. This is a difficult problem in veterinary medicine since it is harder to reassure our patients than it human patients, or at least we have few options in doing so since we can not talk to them. The release of adrenaline and other physiologically active compounds during fearful episodes sensitizes the dog to the effect of some anesthetics and can lead to heart arrhythmia and death. I am not sure this is an avoidable problem in all instances but we do take measures, including pre-operative sedation, to try to lessen this effect.

It may be hard to accept this at this time but I am nearly certain that many of the anesthetic deaths in young patients are due to pre-existing problems that are difficult to detect prior to anesthesia. Chief among these is probably cardiomyopathy which sometimes causes sudden death in adolescent or young adult humans, without anesthesia as a complicating factor. There are many other possible problems, including metabolic enzyme deficiencies, cardiovascular abnormalities other than cardiomyopathy, central nervous system disorders and sensitivity to anesthetic agents that are difficult to detect even with preoperative labwork and good physical examinations. There is also no doubt in my mind that many anesthetic deaths do occur as the result of human error in decision making, carrying our the anesthetic procedure or monitoring the anesthetic patient. One of the problems with being human is that mistakes are an inevitable part of our existence. Differentiating between a vet who is generally very careful but makes one mistake resulting in the death of a pet and the vet who is careless about errors is difficult to do, based on one case. I know of no easy way to do this.

I am familiar with the difficulty accepting an anesthetic death on a personal basis outside of my practice experience. It is very hard to come to grips with. It may help a great deal to discuss this with your vet. If you can not do that, you have the options of reporting the problem to the veterinary board in your state or pursuing a malpractice claim. The resulting investigations may set your mind at ease or may result in actions that do help prevent recurrence of the problem if there was a significant problem in the handling of the case.

Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...