Is anesthesia safe?

[BostonRott]

Based on concerns voiced in another thread regarding the safe use of anesthetics in pets, here is some info, found easily on the web.

An article written for pet owners, followed by two literature cites regarding anesthesia morbidity and mortality.

Is Anesthesia Safe?


Veterinarians anesthetize animals on a daily basis. At least once per week in any clinic, a pet owner expresses concern about anesthesia: Is it safe? Will my pet survive the procedure?

Modern anesthesia is very safe. The risk of a pet dying under anesthesia is less than 1%. The rare patients that are lost under anesthesia are generally emergency surgeries, when the patient's condition is extremely critical. The risk of a pet dying under anesthesia while undergoing a routine spay, neuter, dental or mass removal is extremely low, but this risk can be affected by the anesthetic drugs used and the monitoring of the patient.

Can you imagine an anesthesiologist in a human hospital using ether or chloroform in the 21st century? Of course not. But, unfortunately (and surprisingly), there are no standards of care for veterinary anesthesia, and some clinics are still using out-of-date techniques. Here is a list of questions to ask your veterinarian the next time your pet is scheduled for an anesthetic event:

1) Is pre-anesthetic blood work run? All patients, not just the old or sick, should have basic pre-anesthetic blood tests performed checking the blood sugar, kidney values, and red blood cell count. Many animals will require more extensive pre-anesthetic blood work. Even in animals under one year old, blood work will occasionally detect abnormalities that could affect anesthesia.

2) Are intravenous fluids administered during anesthesia? Many drugs used for general anesthesia tend to cause blood pressure to decrease. Intravenous fluids will combat this decrease. In addition, if there are any adverse reactions under anesthesia, an intravenous catheter allows immediate administration of emergency drugs.

3) Is the pet's body temperature maintained during and after anesthesia? All animals, especially cats and small dogs, lose a lot of body heat under anesthesia. The resulting hypothermia can slow the anesthetic recovery. Anesthetized pets should be placed on a recirculating warm water pad and/or under a warm air blanket. Conventional heating pads are risky because they can cause burns.

4) Is the pet intubated, and what anesthetic gas is used?
Intubation means that the patient has an endotracheal tube placed through the mouth and into the trachea, through which gas anesthetic is administered. The endotracheal tube allows controlled respirations if the patient is not breathing well on his or her own, and prevents accidental inhalation of stomach contents if the pet vomits under anesthesia. Virtually every surgical procedure done in dogs and cats requires intubation and gas anesthesia. The modern gas anesthetics are halothane, isoflurane and sevoflurane. Methoxyflurane is out-of-date.

a. What pain control is used? Surgery hurts! It doesn't matter if the patient is a human, a dog, or a guinea pig. Analgesia is the relief of pain, and in modern anesthetic protocols we strive for pre-emptive analgesia (blocking the pain pathways before the painful procedure starts), and balanced anesthesia (trying to block the pain pathways from as many directions as possible).

5) What monitoring techniques are used? It is critical to monitor the patient's vitals while under anesthesia to ensure that the respiratory and cardiovascular systems are functioning well, and to ensure that the patient is not under too lightly or too deeply. Most important is that someone besides the surgeon (who is occupied) is monitoring the heart rate, respiratory rate, and anesthetic depth.

Additional commonly used monitoring techniques include:

An electrocardiogram (EKG) to monitor the heart rhythm for arrhythmias.
A pulse oximeter to monitor the percentage oxygenation of the blood, which should be close to 100%.
A machine to monitor the blood pressure.
A machine (apnea monitor or capnograph) to monitor the respiratory rate and carbon dioxide level.
Another concern many pet owners have is the cost of anesthesia: Why is it so expensive? Why does Dr. X charge $300 for a dental while Dr. Y down the street only charges $100? As you can see, modern anesthesia involves a lot of equipment and expertise, and this unfortunately costs money. Cutting corners by not intubating patients, not keeping patients warm, or skimping on pain medications and monitoring can save money, but the price is decreased comfort and safety for your pet.

by Laura McLain Madsen, DVM

Date Published: 1/11/2004 5:41:00 PM

Source: http://www.veterinarypartner.com/Content.plx?P=A&A=1607
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This study shows a 0.1% mortality rate in a large study conducted in Canada. That equates to 1 in 1000. When looking at "adverse effect" data, realize that this can include things such as vomitting and other relatively benign adverse effects.

J Am Anim Hosp Assoc. 1998 Jul-Aug; 34(4): 325-35.

Morbidity and mortality associated with anesthetic management in small animal veterinary practice in Ontario.

Dyson DH, Maxie MG, Schnurr D.

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Canada.

During 1993, 66 small animal practices participated in a prospective study to evaluate the incidence and details of anesthetic-related morbidity and mortality. Considering a total of 8,087 dogs and 8,702 cats undergoing anesthesia, the incidences of complications were 2.1% and 1.3%, respectively. Death occurred in 0.11% and 0.1% of cases, respectively. Logistic regression models were developed and showed that a significant odds ratio (OR) of complications in dogs was associated with xylazine (OR, 91.5); heart rate monitoring (OR, 3.2); American Society of Anesthesiologists (ASA) 3, 4, or 5 classification (OR, 2.5); isoflurane (OR, 2.4); butorphanol (OR, 0.35); technician presence (OR, 0.26); acepromazine (OR, 0.24); ketamine (OR, 0.21); and mask induction (OR, 0.2). Complications in cats were associated with ASA 3, 4, or 5 classification (OR, 5.3); diazepam (OR, 4.1); intubation (OR, 1.7); butorphanol (OR, 0.45); and ketamine (OR, 0.17). Cardiac arrest in dogs was associated with xylazine (OR, 43.6) and ASA 3, 4, or 5 classification (OR, 7.1). Cardiac arrest in cats was associated with ASA 3, 4, or 5 classification (OR, 21.6) and technician presence (OR, 0.19). This paper reports the incidences of complications and cardiac arrest in small animal practice and identifies common complications and factors that may influence anesthetic morbidity and mortality. This information may be useful in comparing anesthetic management practices.

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This study shows that puppies born via c-section have a higher survival rate as compared to naturally whelped pups (c-section puppies are exposed to anesthesia). The mortality rate in the dams is 1%.

J Am Vet Med Assoc. 1998 Aug 1; 213(3): 365-9.


Perioperative management and mortality rates of dogs undergoing cesarean section in the United States and Canada.

Moon PF, Erb HN, Ludders JW, Gleed RD, Pascoe PJ.

Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401, USA.

OBJECTIVE: To describe dogs undergoing cesarean section in the United States and Canada, to determine perioperative management, and to calculate survival proportions. DESIGN: Multicenter prospective case series. ANIMALS: 3,908 puppies from 808 dams. RESULTS: Survival rates immediately, 2 hours, and 7 days after delivery were 92, 87, and 80%, respectively, for puppies delivered by cesarean section (n = 3,410) and 86, 83, and 75%, respectively, for puppies born naturally (498). For 614 of 807 (76%) litters, all puppies delivered by cesarean section were born alive. Maternal mortality rate was 1% (n = 9). Of 776 surgeries, 453 (58%) were done on an emergency basis. The most common breeds of dogs that underwent emergency surgery were Bulldog, Labrador Retriever, Boxer, Corgis, and Chihuahua. The most common breeds of dogs that underwent elective surgery were Bulldog, Labrador Retriever, Mastiff, Golden Retriever, and Yorkshire Terrier. The most common methods of inducing and maintaining anesthesia were administration of isoflurane for induction and maintenance (n = 266; 34%) and administration of propofol for induction followed by administration of isoflurane for maintenance (237; 30%). CLINICAL IMPLICATIONS: Mortality rates of dams and puppies undergoing cesarean section in the United States and Canada are low. Knowledge of mortality rates should be useful to veterinarians when advising clients on the likelihood of puppy and dam survival associated with cesarean section.

[Burnsway]

Thanks Gretchen. That is actually one of the sites I did come across. I didn't post it because its stats are actually higher then the 1 in a thousand stats I posted and as you mentioned in the other thread you have to be careful on a board like this not to scare the poop out of people.

Kind of like the vaccination stuff. People need to use common sense in decisions they make for their dogs.

But I sure would hate to be the one who pushed and pushes someone responsible to have the surgery and then their dog died...:(

But I also would hate to be the one that said hey just be responsible and forget the surgery and 3 months later we are helping them whelp a litter of mutts....

I do feel people deserve to know the risk of both sides though.

[BostonRott]

Exactly. People need to make informed decisions, based on scientific facts, not "I heard that......"

Nothing in medicine is without risk. However, understanding what the realistic odds of danger are, understanding your dog's current health status,and how that fits the odds, and understanding the risks of disease if not treated...........then a responsible decision can be made.

[brunie's mom]

I've known people killed in car accidents!! Does this mean I will never drive because there is a chance I can get killed??? NO !!! Chances are that you will not.
It's the same with giving anesthetic to animals. There are chances...but there are always chances in life.
I worked as a vet tech for many years...and assisted in countless surgerys...I do not remember losing one cat or dog that was having routine surgery such as spay/neuters (they are both done very quickly)..neuters not more then 10 minutes (it's the shaving that takes the longest) and spays 20 minutes for immature animals. They are not under very long.

When we did have dogs die was when owners did not bother to spay or neuter their animals...because they were afraid/scared, etc...and then one day the poor old female has closed pyometra (infected uterus). So the old dog must have anesthetic while a mass infection is going on and old. Same with the old male dogs...one day the owner realizes that their male can barely produce a stream of urine or is straining for hours to have a bowel movement. By this time the poor dog's prostate is huge and the only treatment is neutering. This is when things can get very dicey and when they can die.

Most vets now days do blood work ups before giving anesthetic...this helps to tell if the dog can take the anesthesia.

Honestly...I had very little pitty for owners crying over their sick dogs when emergency surgery had to be done. All of this is preventable if the dog is neutered/spayed at an age before the problems start.

Gina