Much like in human medicine, the age of an animal patient can have an important influence on surgery and recovery. Older veterinary patients may present with significant comorbidities seen less commonly in younger patients, such as obesity, diabetes, and cognitive decline, or systemic issues, such as bone loss, as well as heart, kidney, and liver disease.
Indeed, according to Natasha Olby, VetMB, PhD, DACVIM (Neurology), professor of Neurology and Neurosurgery at the North Carolina (NC) State University College of Veterinary Medicine in Raleigh, N.C., organ dysfunction is a primary concern in determining whether a patient is able to withstand anesthesia and the rigors of surgery.
“If we feel they’re safe for anesthesia, we feel comfortable proceeding with the procedure,” Dr. Olby says. “But we will always worry about recovery because there is less reserve in an older animal.”
Frailty a concern
In recent years, Olby adds, a greater focus has been placed on evaluating a patient’s frailty.
“We’re not necessarily looking at the patient’s chronological age,” she explains. “Instead, we’re asking how much physiologic reserve does this patient have? Frailty is a standard in human medicine, and we’re seeing it used more in veterinary medicine, whereby the practitioner quantifies the net effect of numerous age-related things that may be affecting the patient. We call it a frailty phenotype, or a frailty index.”
“Rather than looking at an animal’s chronological age and saying, ‘This dog is 14 years old so we shouldn’t do surgery even though it is otherwise in great health, and everything looks fine,’” Olby continues, “we should be summarizing what its physiologic reserves are going to be like, because surgery in itself is always dictated by how much reserve the patient has. With age, you see an erosion of reserve, but it happens at different rates in different animals.”
Denis Marcellin-Little, DEDV, DACVS, DACVSMR, professor, Surgical and Radiological Sciences at the University of California, Davis (UC Davis), routinely performs complex orthopedic surgeries on a wide variety of species. Age, he says, can have a dramatic impact on a geriatric animal’s bones, which, in turn, can influence a veterinarian’s surgical plan.
One of the biggest concerns, according to Dr. Marcellin-Little, is risk of fracture during a procedure.
“We often perform hip replacements, and there is evidence that the risk of a fracture during implantation of the stem into the femur increases after eight years of age,” he says. “There is a bit of a downward slope in bone quality after eight to 10 years of age. We have to start making an effort to understand the quality of the bone more when we plan procedures that will rely on that bone over a long period of time.”
Marcellin-Little notes the various adjunctive options available to surgeons to reinforce bones, including surgical repairs to make aging bones more stable despite loss of bone quality, and biological approaches, such as bone morphogenetic protein 2 (BMP-2), which assists in the development of new bone.
The type of procedure can also determine the degree of influence a patient’s age may have on surgery. The more invasive the procedure, the more rehabilitation would be needed to recover function, and the harder it would be to recover if the patient has become frail, Olby says.
“Major orthopedic surgery on an animal that has already lost a lot of muscle because of frailty, for example, will result in a more difficult recovery,” she explains. “[Additionally], while it’s not surgery, annual dental cleanings are commonly performed under anesthesia, which can pose a risk in older patients. But bacterial infections in the mouth also carries a risk. The question becomes: at what point does the risk of surgery outweigh the benefit?”
Challenges of recovery
For geriatric patients, recovery from surgery can often be as challenging as the procedure itself. While incisions usually heal well, certain health issues, such as diabetes or hyperadrenocorticism, may adversely impact healing or increase risk of infection, Marcellin-Little says. The effect of age on bones, organs, and internal systems may cause healing to take longer, too.
“We build a safety margin into our activity oversight plans for older patients,” Marcellin-Little explains. “We worry a bit if there is a major metabolic problem or liver disease, or if the patient is immunocompromised. We still do surgery on immunocompromised patients, we’re just super cautious about their risk of infection.”
Further, older patients are much more likely to have osteoarthritis and muscle loss and, therefore, be less mobile, Olby adds.
“The more impacted the patient is, the harder it is to recover and regain mobility after surgery, no matter what the surgery is,” she says. “One beneficial approach is to perform rehabilitation ahead of surgery to increase the patient’s reserve or mobility.”
That said, a geriatric patient’s species is rarely a factor when considering the impact of age on surgical decisions.
“There are species differences, but I don’t think we could say clearly, this species ages better than that species,” Olby says. “A surgeon should evaluate comorbidities, the disease requiring the surgery, etc., for each individual patient.”
She offers the example of a 16-year-old cat with a meningioma—a type of cancer that can be a good candidate for surgical removal.
“It sounds terrible to suggest brain surgery on a geriatric cat, but, as long as they don’t have other conditions that make anesthesia too risky, such as severe kidney disease, they can bounce back from the surgery very quickly,” Olby says. “If you put the same scenario in a dog, it would be a little different, but more because meningiomas are more difficult to remove completely in dogs rather than anything to do with age.”
Misconceptions
Community practitioners and owners often have misconceptions when it comes to performing surgery on a geriatric patient. One of the most common is it is pointless to perform surgery on older animals because they are at the end of their lifespan.
“The truth is every animal lives its own lifespan, so it’s more important to assess a patient’s frailty,” Olby says.
Likewise, a heart murmur may also cause a veterinarian to advise against surgery due to concerns around anesthesia. In these scenarios, Olby advises a more thorough cardiac evaluation, as many animals with a heart murmur are not yet physiologically affected.
“Sometimes practitioners can be very black and white when it comes to surgery,” Marcellin-Little adds. “They tend to say ‘yes’ or ‘no’ for surgery rather than modulating the procedure or recovery. To say ‘no’ to surgery is often a suboptimal decision. Aging is a complex spectrum, as is surgery and recovery.”
Marcellin-Little’s surgical experience ranges from dogs and cats to two koi with scoliosis, a unique case study he wrote about with Olby and others.1 His advice to practitioners who may be thinking of including surgery among their services—especially on older patients—is to trust their own judgement when determining if a patient is a good candidate, but to not hesitate to reach out
when necessary.
“If you have specific concern, discuss it with a more experienced colleague, or consider a referral,” Marcellin-Little says. “Just play it safe.”
“Sometimes a surgical procedure may look a little complicated beforehand, but if it helps prevent a catastrophic complication, it’s generally worth it,” he adds.
Don Vaughan is an award-winning writer who frequently writes about veterinary-related topics.
References
- Stabilization of scoliosis in two koi (Cyprinus carpio) by P D Govett, N J Olby, D J Marcellin-Little, D S Rostein, T L Reynolds, G A Lewbart. Vet Rec. 2004 Jul 24:155(4):115-9. Doi: 10.1136/vr. 155.4.155.