While customized monitoring and drugs should be provided for every patient, those falling into the geriatric category—in the last 25 percent of their life expectancy—require extra precaution as underlying health conditions may be more prevalent.
Veterinary specialists say senior patients in need of a procedure that requires anesthesia should not be passed off as too old to handle sedation or anesthesia based on age alone. Yet the misconception accounts for one of the top three concerns with using anesthesia.
"Owners are reluctant to care for the engine because they assume the body will go bad and they fail to care for the body because they think the engine will go,” Harvey continues. "If nothing is being cared for, it will surely fall apart.”"When veterinarians and pet owners think age is an obstacle to necessary maintenance, it reminds me of mistakes made with older cars,” says Ralph Harvey, DVM, M.S., Dipl. ACVA, associate professor of anesthesiology at the University of Tennessee College of Veterinary Medicine in Knoxville and an AAHA anesthesia task force member.
According to the recently released American Animal Hospital Association (AAHA) Anesthesia Guidelines for Dogs and Cats, pre-anesthetic patient assessment and preparation is key to initiating a smooth anesthetic procedure, while monitoring will allow for immediate action if any issues occur during the procedure.
"A trained veterinary technician is ideal under any anesthetic procedure,” says Richard Bednarski, MS, DVM, Dipl. ACVA, of the College of Veterinary Medicine at The Ohio State University in Columbus, chair of the anesthesia guidelines task force. "A veterinarian can’t effectively concentrate on the procedure and anesthesia. A technician needs to be able to recognize any deviation from the norm and know how to act.”
While some procedures can only be performed under anesthesia, even those that may be attempted without sedation often prove more stressful for the animal than a properly handled anesthetic procedure.
"If there are realistic alternatives, sure, one should consider them for any patient,” says Khursheed Mama, DVM, Dipl. ACVA, associate professor of anesthesiology at Colorado State University in Fort Collins, Colo. "However if the veterinarian is not comfortable sedating or anesthetizing a senior animal because of age-related concerns, he should consult with an anesthesiologist to determine an appropriate plan [vs. delaying it until the situation is worse]. And if that is not feasible in the practice environment, it might be worth referring that patient for its anesthetic care—as one would for challenging surgical or cardiac procedures.”
Experts say alanine transaminase, creatinine, urinalysis and specific gravity are the minimum tests that should be performed before administering anesthesia to a senior pet. Additional tests may be needed, depending on the findings. Additionally, owners should be told in advance about the associated financial investment, as advanced testing may be necessary.
"There is an increase in cost to care for senior pets, but that comes with an increase in safety,” Dr. Harvey says. "Sometimes an X-ray or ultrasound is needed to make sure anesthesia is safe for a patient. In addition to testing, a veterinarian must be in tune with an older patient’s psycho-social issues. Sometimes an older animal doesn’t do as well at the veterinary practice, away from its family and home. Considerations should be made to make the stay less stressful.”
Drug choice is different for senior animals versus those in their prime, experts say. A practitioner should look for a drug that facilitates a rapid, smooth recovery for senior patients.
"Selecting a drug that helps create a smooth transition from awake to asleep and asleep to awake is best,” Harvey says. "I prefer an opioid, multimodal approach to anesthesia that allows for good tissue perfusion.”
Harvey says that in addition to health concerns, some breeds may have higher sensitivity to anesthesia, such as sight hounds and possibly some lines of boxers. These concerns, along with a senior status, make blood work and a thorough physical exam mandatory before determining anesthesia qualification status.
"Older animals don’t metabolize as efficiently or quickly as younger animals,” Dr. Bednarski says. "Considering this point, a veterinarian will want to scale the dose back. When using acepromazine, dose at the low end of .02 mg/kg for a 13-year-old Labrador in need of a dental versus .1 mg/kg for a 1-year-old Labrador having a spay procedure. Also, a benzodiazepine like midazolam plus an opioid has minimal cardiovascular side effects–and can be considered a poor sedative for younger animals, but is good for use in senior pets as a pre-med tranquilizer.”
Heart rate and rhythm, blood pressure (direct or indirect), body temperature (rectal or esophageal), respiration (capnography) and oxygenation (pulse oximetry) are among routine physiological parameters that should be monitored in a senior patient.
"Supportive care should include intravenous fluids (and inotropes if necessary), external heat if necessary and mechanical ventilation if necessary,” Dr. Mama says. "That said, a patient that is doing poorly despite appropriate anesthesia drug selection, support and monitoring may need to be recovered (when the situation allows) so as not to exacerbate any underlying disease.
"Older patients are more likely to have concurrent disease or mild to moderate organ dysfunction that would require the routine anesthesia protocol be adjusted,” Mama continues. "A thorough pre-operative physical examination and blood work should help identify most of these and allow the veterinarian to provide appropriate care. For example, if one were to auscultate a heart murmur upon physical examination, further diagnostics might be suggested to determine the specific cause so that it may be managed appropriately.”
Mama notes that a regurgitant murmur is common in older dogs and is managed quite differently from a stenotic murmur. If an elevation in renal parameters is noted on the chemistry panel, management strategies might include pre-, intra- and post-operative intravenous fluid therapy, administration of diuretics, supportive drugs to ensure blood pressure is normal, etc.
Not all elderly patients will require additional or unique care, but identifying this ahead of time and planning for it when necessary is appropriate.
"My bias is that there are gaps in our knowledge with normal progression or deterioration and the variability one might see,” Mama says.
"It’s difficult to get knowledge regarding organ function over the life span of the animal,” Mama adds. "The other aspect is regarding management, and there is a need to educate the general veterinarian on options available to them to manage these patients. However, many practice situations are not conducive to this, or individuals don’t have the comfort level to manage patients appropriately.”
Because many more owned canines and cats are living to a senior age, better protocols have been formed for their care. AAHA, for example, also provides Life Stages Guidelines.
"Clients will expect their primary care practitioner to be able to meet the needs of their senior pet,” Bednarski says. "Because of this demand, there is a lot of continuing education available on senior pets for veterinarians and their staffs. There is no excuse not to be current.”
To watch a video of AAHA's anesthesia guidelines in action, click here.