Dog Anesthesia Risks of Death

Researchers studied more than 157,000 cases of dogs requiring general anesthesia/sedation between 2010 and 2013 and reported the risk of death in dogs. That published study includes insights into the relative risks based on dogs’ age, health status, type of procedure (including spay/neuter) and even nose length. It’s supposed to be reassuring, but even an experienced dog mom like me learned a lot. Don’t miss the context and warn of a possible overestimation of the risk at the bottom of the page.


Risks of canine anesthesia

Statistics on anesthesia risks in dogs

Basically, the headline is that the risk of dogs dying from general anesthesia or sedation in general is about 100 in 100,000 or slightly more.

This is how the detailed data breaks down. If the 157,318 verified cases:

  • 159 dogs died within 48 hours (0.10% or 100 out of 100,000)
  • 219 dogs died within 2 weeks (0.14% or 140 out of 100,000

Anesthesia Risks in Dogs Data Graph 1 - shows 378 deaths among 157,318 dogs requiring anesthesia or sedation for a procedure

Anesthesia risks in castrated/neuter dogs

When researchers looked specifically at neutering surgeries, the data showed that only 8 out of 89,852 of these surgeries resulted in the death of a dog:

  • 5 within 48 hours
  • 3 within 2 weeks

Data on anesthesia risks in dogs - shows 8 deaths in 89,852 spay/neuter surgeries

Anesthesia Risks in Dogs – Age

Compared to dogs 0.5 to 1.5 years old, older dogs are at higher risk of anesthesia:

  • Dogs aged 5 to 7 years are 4.9 times more likely to die.
  • Dogs aged 7 to 9 years also face a 4.9 times chance of death.
  • Dogs over the age of 9 have a 12.8 times risk of death.

Statistics on anesthesia risks in dogs - show that dogs over the age of 5 years are at a higher risk of death
Anesthesia risks for dogs - graph showing which dogs have higher or lower risks

What about race and other factors?

The study found that some breeds face a higher — or lower — risk of death from anesthesia. For example:

  • rottweiler are 8.1 times more likely to die from anesthesia – poor Rotties! Remember how high your risk of bone cancer is too?
  • West Highland White Terriers are 5.4 times more likely to die from anesthesia
  • BUT … Cocker Spaniels have much lower odds (only 0.1)
Length of a dog’s nose and anesthetic risks in dogs

While other studies have reported higher anesthetic risks for dogs brachycephalic breeds (dogs with smoothened faces), this “found no significant difference between mesocephalic and brachycephalic breeds.” Mesocephalic means noses of medium or normal length.

However, dolichocephalic Dogs (those with long skulls and noses, like Greyhounds, Collies and Great Danes are faced with higher chances of anesthesia risks in dogs (3.7-fold probability).

Health Status Ranking

The American Society of Anesthesiologists scores each health status of the patient. That’s not surprising Dogs with a score of III or higher are at greater anesthetic risk to dogs than other dogs. In these cases, the surgeries or diagnostic procedures that require anesthesia or sedation are likely to be more invasive and urgent. And the researchers found that “more urgent procedures were associated with a higher likelihood of death.”

  1. ASA health status I means a normal/healthy patient.
  2. ASA health status II denotes a patient with mild systemic disease.
  3. ASA health status III denotes a patient with severe systemic disease.
  4. ASA health status IV denotes a patient with a severe systemic disease that poses a continuing threat to life.
  5. ASA Health Status V means a patient in an incurable condition who is unlikely to survive without surgery.
Anesthesia risks for dogs - as a health status chart

Which surprised me

Even after living with dogs my whole life I guess I’ve always felt that once dogs recovered from surgery they would be fine. And I’m relieved to say that I’ve never had a dog die from anesthesia.

However, the study looked for death within 48 hours and within 2 weeks, and that surprised me. I stop worrying long before then. I don’t see anywhere in the paper showing how many dogs fell into these time of death categories, but the paper mentions searching for these causes of death:

  • euthanasia
  • cardiorespiratory
  • Gastrointestinal
  • neurological
  • kidneys
  • Unclear, but not euthanasia

While the overall likelihood of death related to anesthesia is indeed low, based on this article, I know that when rare things happen to your dog, they FEEL NOT RARE. I learned this when we lost our original canine heroine (Lilly) to a rare rabies vaccine reaction.

The study found a higher risk (8.5 times greater than likelihood) of having dental procedures within 48 hours. That seems absurd to me. BUT on the plus side, they found that minor soft tissue surgery had a lower probability (0.3) than even diagnostic procedures.

Risk of anesthesia in dogs Quote from study - possible overestimation

Context and Cautions

In the section where the authors list possible study limitations and the like, they specifically state… “Limitations of the current study related to possible overestimation of risks of death associated with general anesthesia/sedatives and possible misclassifications of both cause of death and risk factor data and this finding was derived from the cause of death and clinical records. It is possible that further detailed postmortem examination/autopsy may have excluded a portion of the dogs classified as cases in the current study.”

In an interview, one of the co-authors said he hopes the information “can help owners deal with those fears [of anesthesia] if you understand the real anesthetic risk, it’s not that high: 14 deaths per 10,000 dogs.”

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