Understand anesthetic risks in pets

Many people become hesitant when considering procedures that require general anesthesia for their pets. It is understandable that pet owners would be concerned about the risks of anesthesia, and they may even have known a previous animal (or human) that had complications from being anesthetized. Ultimately, however, a good understanding of risks and benefits can help make a more informed decision of whether or not to anesthetize a pet.

The obvious benefit of general anesthesia is to allow the veterinarian to perform painful and/or invasive procedures. The need for anesthesia may be extremely urgent in some cases (as with a bloated, twisted stomach), medically important although not immediately life threatening (as with a pet that has dental disease), or may even be considered more “elective” (as with spays, neuters, and the removal of benign lumps).

But it is not the benefit of anesthesia that is the sticking point for pet owners — it is the possible risk. No anesthetic procedure, no matter how “routine,” is completely safe. Thankfully, though, significant problems are very rare, and there are things that can be done to minimize any risks and increase the likelihood of a successful outcome.

Healthy pets are less likely to have anesthetic complications than unhealthy ones. “Health” in this sense is a broad sense of the term — appropriate weight, good diet, healthy organ function, lack of infection and strong immune system, for example.

Veterinarians may use a scale developed by the American Society for Anesthesiologists to determine a pet’s health status for anesthesia. This scale, developed initially for human patients, categorizes pets in five groups; the ASA 1 group is normal and healthy, while the ASA 5 group is severely sick or injured and will likely not survive without an operation. Determining the ASA status helps a veterinarian appropriately prepare for the details of the anesthetic plan.

An animal’s ASA status is determined by a few different factors. A physical exam is the first step; a thorough examination will detect physical abnormalities such as a heart murmur or enlarged lymph nodes. Animals undergoing anesthesia should have a recent blood panel to look for any internal health concerns. For young pets, this may be more of a “miniature” panel that assesses key parameters such as liver and kidney function. Older pets should have a more complete screen before considering anesthesia.

Other factors that may affect an animal’s ASA status include ongoing medical conditions (e.g., diabetes), the use of medications, and the results of other diagnostic tests (e.g., X-rays).

This is not to say that all ASA 1 pets will be guaranteed a successful anesthesia, or that pets in other ASA categories are destined to have complications. Every individual pet in every individual circumstance is different, and should be treated as such. Different medications in different strengths may be used, or surgical approaches might be changed, in pets with varying levels of risk.

Regardless of ASA status, all anesthetized pets need to have their vital signs monitored by a technician. This may include analyzing blood pressure, heart rate, breathing rate, blood oxygenation, and body temperature. Any changes in these parameters must be detected early enough to generate an appropriate response. Many problems can be managed by adjusting the anesthetic plan as needed.

Unfortunately, there are rare cases when animals have significant adverse effects from anesthesia, ranging from organ dysfunction to death. This can be a scary thought for a pet owner, even knowing that the vast majority of pets undergoing anesthesia do just fine.

Pet owners with concerns about anesthesia should talk with their veterinarian. There are several questions that they may want to ask: Will my pet have pre-anesthetic blood work? What risk category does my pet fall into? Will there be a dedicated technician monitoring anesthesia? What will be monitored? Will my pet have an intravenous catheter to provide fluids and allow quick access for injections in case of emergency? What are the downsides of not doing anesthesia? Do the benefits of anesthetizing my pet outweigh the risks?

This dialogue can hopefully help owners be prepared to make a truly informed decision about anesthesia on behalf of their pets.

— Keith Rode is a veterinarian at Woodland Veterinary Hospital and a graduate of UC Davis. For more information, call 530-666-2461.