As the veterinary industry continues to improve and innovate, access to better care throughout an animal’s life has increased pets’ overall life expectancy. As such, the senior companion animal demographic has drastically grown, and currently sits at 44 per cent of the total pet population. This shift makes understanding and implementing senior-specific care for aging patients more important than ever.

In January of 2023, the American Animal Hospital Association (AAHA) published a set of recommendations for working with senior pets.¹ The resource—titled, 2023 AAHA Senior Care Guidelines for Dogs and Cats—breaks down care into two lists:

• diagnostic tests; and
• recommended frequencies and diagnostic approaches by body system.

In addition to specific testing and treatment guidelines, AAHA also advocates for special accommodations for clinics’ grey-muzzled patients, including extra time during appointments, the offer of resources about common conditions and end-of-life care, and inclusive marketing campaigns, featuring photos and stories of older pets.

Tracking important biomarkers

Regular diagnostic testing of senior dogs and cats, as suggested by AAHA, can help veterinarians detect and begin treatment for health conditions before clinical signs present. Specifically, regular tests able to provide early indication of common conditions in senior pets include Thyroxine (T4) and NT-proBNP—two biomarkers that have been proven to indicate potential problems within the thyroid and heart, respectively.

Elizabeth Rozanski DVM, DACVIM, DACVECC, defines a biomarker as a “measurable substance in an organism that changes in response to a condition or exposure.” Indeed, biomarkers serve as an internal alarm system, giving veterinarians access to the inner workings of an animal through a small blood or serum sample. When levels are irregular, additional diagnostic testing can be performed to determine specific conditions within what could trigger that specific biomarker’s variation.

“Screening of senior pets without symptoms is likely to help detect changes earlier, which leads to a longer quality of life,” explains Jennifer Mathis, DVM, CVPP, a veterinary dental specialist practicing in Des Moines, Iowa.

To detect potential health concerns even earlier, Dr. Mathis recommends utilizing quantitative in-clinic biomarker testing for both T4 and NT-proBNP. Getting numeric results at the point of care while the patient is still present allows veterinarians to make treatment decisions and act on them immediately. This method also avoids the cost, wait times, and potential sample degradation associated with reference labs.

In addition, once a patient has been formally diagnosed, biomarkers can be an invaluable monitoring tool to gauge the overall effectiveness of treatment. If the levels are not behaving in an ideal way, veterinarians can quickly change the course of treatment to further increase quality of life (QoL). In-clinic testing can also be used for monitoring to provide updates on the treatment’s effectiveness in real time.

Monitoring thyroid conditions with T4

Among the key biomarkers to monitor in seniors is T4. This is a major thyroid hormone that regulates metabolic rates and activity in various organs in both dogs and cats. Testing T4 levels is often used along with other diagnostic measures to detect canine hypothyroidism, as well as feline hyperthyroidism (i.e. the most common endocrine disease impacting geriatric cats). Decreased T4 levels can point to hypothyroidism and increases can indicate hyperthyroidism.

While AAHA’s guidelines recommend annual testing in dogs, Mathis cautions that annual T4 testing in senior dogs can lead to a misdiagnosed hypothyroidism case, given that decreased T4 levels can be indications of other conditions, as well. Instead, she recommends testing thyroid stimulating hormone (TSH) in dogs for the initial hypothyroidism diagnosis and using T4 testing to monitor dogs that have already been diagnosed.

Meanwhile, per the guidelines, senior cats are at an increased level of urgency for T4 testing, with annual screening “strongly recommended” by AAHA. Mathis agrees with this suggestion.

“For senior cats, T4 testing is underrated and needs to be done annually,” she says. “Cats commonly get hyperthyroidism as they age, which is diagnosed and monitored through T4 testing. The sooner hyperthyroidism is detected, the better the outcome before it causes secondary renal issues.”

In addition to performing regular testing, veterinarians should be aware of the clinical signs of both canine hypothyroidism and feline hyperthyroidism; unfortunately, however, these common diseases present non-specific symptoms, and thyroid conditions may not be the go-to diagnosis. Notably, though:

• If a dog is exhibiting lethargy, mental dullness, weight gain, or weakness, these things could be due to decreased metabolism as a result of hypothyroidism.

Conversely:

• If a cat is losing weight or showing signs of polyphagia, polyuria/polydipsia, or hyperactivity, these symptoms could indicate an overly increased metabolism from hyperthyroidism.

Any of these symptoms—particularly if they are presenting in a senior animal—warrant TSH or T4 testing to determine if the thyroid is the underlying cause.

Tracking heart failure with NT-proBNP

According to Dr. Rozanski, NT-proBNP tests track levels of natriuretic peptides, which are released with the biological goal of helping return the heart to a normal state when an animal is experiencing atrial stretching.

Given NT-proBNP has been proven as both stable and reliable, quantitative NT-proBNP testing can be used to indicate both the presence and severity in cats with hypertrophic cardiomyopathy (HCM) and dogs with myxomatous mitral valve degeneration (MMVD).

Diagnosing heart disease in cats can be particularly challenging.

“Cats are liars,” Rozanski says. “Some cats can come in with no murmur but have severe heart disease, and some cats have severe murmur and no heart disease.”

This lack of correlation between clinical heart disease signs and presence of the disease itself further asserts regular biomarker testing as a critical method to determine a feline’s HCM status—particularly since the disease becomes more prevalent and common with age. If a feline patient has elevated NT-proBNP levels, Rozanski recommends an echocardiogram to see the full extent of any heart disease and damage before pursuing treatment.

Dogs, by comparison, are generally easier to diagnose. The presence of a murmur is a fairly reliable indication of heart disease with the severity of the murmur being a solid clue into the extent of the disease; however, it is not a perfect correlation. Both Mathis and Rozanski have had canine patients with no detected murmurs that were later diagnosed with heart disease. Unfortunately, in many cases like this, missing the initial opportunity for early detection and intervention can lead to more rapidly decreasing QoL and earlier heart failure than if treatment had been implemented.

Given the occurrence of these cases, early detection of heart disease requires more than clinical symptom evaluation. Indeed, regular NT-proBNP testing, especially as a dog gets older, helps ensure heart disease is caught and treatment is initiated as soon as possible.

Getting the whole picture before anesthesia

In addition to annual testing, AAHA recommends determining NT-proBNP levels before an anesthetic event; however, Mathis encourages veterinarians to also include thyroid monitoring in their pre-anesthesia checklist. Her practice is largely focused on dental care, which includes annual anesthetic procedures for both dogs and cats. To ensure anesthesia is being administered as safely as possible, Mathis utilizes an array of in-clinic quantitative biomarker tests, including canine TSH, canine and feline T4, and canine and feline NT-proBNP.

“In-clinic testing makes me feel much better about my anesthesia planning prior to procedures, and I love that the results are so fast,” she says. “Dogs and cats need annual anesthetic dental procedures, so annual testing of all parameters as suggested in the guidelines is not only good for baseline values, trend monitoring, and organ or disease status, but is also helpful as pre-anesthetic lab work leading into a dental procedure.”

“Changes in NT-proBNP levels can greatly change an anesthetic treatment plan, so I recommend testing for all ages prior to anesthesia in dogs and cats,” Mathis continues. “A hyperthyroid cat could also be an anesthetic issue, so knowing the thyroid status in a cat prior to anesthesia is helpful.”

Understanding the full picture of an animal’s health is crucial before administering anesthesia at any age; however, the growing prevalence of heart and thyroid conditions that can further increase the risk of going under anesthesia as an animal gets older makes testing—even in cases without clinical signs—a necessary step.

Providing a longer, happier life

Care for senior pets is multi-faceted. In addition to these crucial biomarker tests, AAHA encourages veterinarians and owners to work together on additional medical adjustments, behavioural management, awareness of comorbidities, and environmental modifications.

Many owners believe pets will, inevitably, degrade physically, mentally, and behaviourally as they age, but this does not have to be the case. As the veterinarian, your role, as laid out by AAHA, “includes providing medical care and support to senior pets to maintain their quality of life, as well as supporting and educating clients on proper senior animal care and addressing any misconceptions about the aging process.”

Additionally, per the guidelines, aging is not a disease. Every year of an animal’s life means more time bringing joy to its family—even if this joy looks a little different than it did in the puppy stage. Understanding the nuances of care for senior dogs and cats and acknowledging the natural changes that come with age can be the best way to “test” longevity boundaries and give these families even more years of love with their pets.

Randy Knick, MBA, is president of Bionote USA, a medical diagnostics research and development company. With more than 30 years of market experience, Knick leads Bionote USA utilizing his professional experience in the United States, Latin America, Australia, Canada, and the Caribbean, along with an extensive history in government sales.

References

¹ The American Animal Hospital Association, 2023 AAHA Senior Care Guidelines for Dogs and Cats: aaha.org/aaha-guidelines/2023-aaha-senior-care-guidelines-for-dogs-and-cats/home

² See, “Getting the Most of Your Baseline Lab Work: The Role of NT-proBNP in Wellness and Risk Assessment” webinar, presented by Elizabeth Rozanski, DVM, DACIM, DACVECC (via bionote.com/events)