If your dog is facing surgery that requires anesthesia, there is nothing unusual about wondering if some dogs are more sensitive to anesthesia than others. In fact, according to many veterinary surgeons, this is a very common question. Today, thanks to the efforts of many breeders to create breeds with specific characteristics, there are now more than 170 different recognized breeds of dog in the U.S. alone. Despite the incredible number of different breeds, veterinary experts agree that while there is significant concern regarding sensitivity to anesthesia, there is only one breed that has been found to actually have a natural anesthesia sensitivity, and that is greyhounds.
Having said this, you should be aware that while a specific breed may not actually have a true anesthesia sensitivity, any use of anesthesia may require specific conditions. In part, this is the fault of human beings. We have invested decades in customizing dogs through breeding and genetic engineering. While this may have created what some might call the "perfect" breed, doing so has created unique physiologic, anatomic, and metabolic characteristics. In turn, this may have a significant impact on how a particular breed will react to anesthesia.
So many times, people take their dogs in for surgery, only to tell their vet that their breed is "sensitive" to anesthesia. This could be Chihuahuas, bulldogs, Great Danes, and virtually any breed in the country. Far too many people labor under this myth and put their dog at risk of not getting the surgery they need or making life unnecessarily difficult for the surgeon. The reality is that sensitivity to anesthesia in dogs is far more myth than it is a reality.
The facts behind this myth are a little hard to trace, but just like people, some dogs react to anesthesia a little differently than others. Does this mean they are sensitive to anesthesia? Quite possibly, but then so are some people. At the same time, it does not mean that the entire breed suffers from the same sensitivity. But this is how so many different rumors get started, even those that have little to no basis in scientific fact.
Rather than sensitivity to anesthesia based on breed, the size of the dog is more of a factor. For example, if you give the same amount of anesthesia to a Chihuahua you would use for a Great Dane, you might kill him. On the converse side of the coin, if you gave the Great Dane the same dosage as you would a Chihuahua, the Great Dane would still be wide awake for his surgical procedure.
Many, if not most, vets have had at least one patient who has told them their dog is too old for anesthesia. The reality of this is that age plays a very small role in deciding whether or not to anesthetize your dog. As long as your dog passes all of the preliminary workups, there is no reason why he cannot undergo anesthesia and the subsequent surgical procedure.
Your vet will conduct blood tests, x-rays, ultrasounds, and a full physical exam as needed to ensure your pup is healthy enough for surgery. Your vet will custom tailor the amount of anesthesia and the method used to meet the age and health of your four-legged friend. If things look complicated, the vet may call in a board-certified anesthesiologist for a consultation.