The canine cancer conundrum: Insights into screening and detection

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Cancer is a reality that many dogs and owners must confront. Although cancer is often associated with old age, findings from recent studies have shown the median age of a cancer diagnosis in dogs is approximately 8.8 years, when many dogs still possess the energy and mischievousness of their puppy years.¹

As veterinarians know all too well, cancer does not discriminate. Veterinarians play a pivotal role in this journey. The importance of their work extends beyond the clinical environment because they have the power to educate, empower, and support pet owners in making informed decisions about their pet’s health.

With this responsibility in mind, navigating through the vast landscape of canine cancer testing might feel overwhelming. Yet by delving deeper into these tests, their evaluation, and their far-reaching impact, veterinarians can elevate their quality of care. Grasping this knowledge enables veterinary professionals to effectively relay these options to pet owners, strengthening the veterinarian-client bond and preserving the pet parent’s bond with their dog.

Consider Buddy, a spry 9-year-old chocolate Labrador retriever who trotted into the veterinary clinic for a routine checkup. He showed no outward signs of illness, and his vibrant energy belied his age. However, due to his breed and age, both of which statistically put him at a higher risk of developing cancer, his veterinarian suggested a cancer screening test alongside routine blood work.²

Navigating the conversation around cancer—a topic often laden with panic and anxiety—was challenging for Buddy’s veterinarian. Cancer can evoke strong reactions from pet owners and veterinarians alike. However, the power to detect, manage, and potentially change the course of the disease begins with screening. And to wield this power effectively, open dialogue about testing is necessary, even if uncomfortable.

When the results came back, they pointed to a suspicion of cancer, and confirmatory diagnostics unmasked early-stage lymphoma. The news was a bitter pill to swallow, but the veterinarian was not without hope. Early detection paved the way for swift treatment decisions, and Buddy was soon on a therapeutic plan designed to provide the best possible outcome.

It’s important to acknowledge the reality that not all stories have a happy ending like Buddy’s. However, it is precisely in this uncertainty where the importance of early detection tests emerges. Despite pet owners becoming increasingly receptive to preventive care for common illnesses,² the specter of cancer still casts a daunting shadow. The weight of a potential cancer diagnosis can often make pet owners averse to seeking out these tests. Yet veterinary professionals must remember that the goal of early-detection tests isn’t to confirm fears, but rather, to equip everyone with knowledge.

Early detection is a 2-pronged concept. On one hand, it means identifying cancer before any clinical signs emerge. On the other hand, it involves catching disease in its early stages. Although we’re still gathering robust data on the prognosis of dogs with cancer that is detected presymptomatically, compelling evidence shows that catching cancer early improves the outlook. For instance, findings from a retrospective study focusing on dogs with stage I and stage II splenic hemangiosarcoma reveal a significant difference in prognosis: Dogs with stage I disease had a median time to progression almost twice as long as those with stage II disease (338 vs 151 days, respectively).³

Now let’s draw some parallels with human medicine. Recent data suggest that early-stage detection and diagnosis in humans paves the way for more timely surgical interventions and resections compared with late-stage diagnoses.⁴

Why does this matter? Simply put, early intervention reduces the risk of death from cancer. This shows us the invaluable role that early detection plays—a goal within our reach through regular cancer screening tests that benefits both ends of the leash.

If you’ve ever felt like you’re searching for a tennis ball in a field full of frisbees while trying to understand technical terms in canine cancer screening, you’re not alone. Let’s make sense of one often-used term: liquid biopsy.

A liquid biopsy is a noninvasive test that picks up on cancerous mutations or changes using a bodily fluid sample, usually blood. It’s like the newer, better model compared with the traditional, invasive tissue biopsy. It’s easier on the wallet, more flexible, and readily available. But how do we know whether a liquid biopsy is accurate? Enter 2 critical factors: sensitivity and specificity. This dynamic duo is the compass for determining the reliability of the test.

Sensitivity and specificity: The pillars of accuracy

Imagine searching for red apples in a large basket full of various fruits. Sensitivity is akin to the ability to find all the red apples. If your method of searching is highly sensitive, you will find all the red apples without missing any—meaning fewer false negatives. However, if your method isn’t sensitive enough, apples might be overlooked, mistaking them for other fruits.

Specificity, on the other hand, is like your ability to correctly exclude all the fruits that are not red apples. A method with high specificity will correctly identify all the nonapples, resulting in fewer false positives—meaning you are less likely to mistakenly identify a different fruit as a red apple.

Understanding the balance between sensitivity (not missing any red apples) and specificity (not mistaking other fruits for red apples) is crucial in interpreting the efficacy of a test. It is equally important for veterinarians to communicate this balance effectively to pet owners when discussing the benefits, limitations, and possible outcomes of cancer testing.

The outcomes of canine cancer screening tests can be thought of as pieces of a puzzle because they are valuable and informative but not the whole story. Instead of delivering a definitive diagnosis, these tests are best considered in concert with physical examinations and other blood work. They lay the groundwork for veterinarians to establish a baseline for pets’ health—a reference point that becomes invaluable when detecting irregularities.

Such a nuanced understanding forms the backbone of conversations with
pet owners about cancer screening results. These dialogues, although delicate, are where veterinarians, as trusted advisers, demonstrate their empathy. Highlighting that the results are guideposts rather than final destinations can be challenging but opens an opportunity for strengthening the bond of trust through honest and transparent communication.

This role of veterinarians becomes even more pivotal when we consider the emotional toll these discussions can have on all parties involved. The onus is on every member of the veterinary team to ensure a supportive working environment—fostering respect for interpersonal relationships, effective stress management, and open communication.

As the team presents a unified front, their primary focus remains the best interest of the pets in their care. Guiding pet owners, managing expectations, and bolstering resilience form the cornerstone of their shared commitment—a future where every dog stands a fighting chance against cancer.

Devin DeVoue is a seasoned marketing manager at Volition Veterinary and a dedicated member of Chestnut Hill College’s board of directors. With more than a decade of experience working with veterinarians, he brings a unique blend of expertise and passion to his role. Outside work, he cherishes quality time with his rescue pit bull, Ava.

References

1. Rafalko JM, Kruglyak KM, McCleary-Wheeler AL, et al. Age at cancer diagnosis by breed, weight, sex, and cancer type in a cohort of more than 3,000 dogs: determining the optimal age to initiate cancer screening in canine patients. PLoS ONE. 2023;18(2):e0280795-e0280795. doi10.1371/ journal.pone.0280795
2. Treggiari E, Borrego JF, Gramer I, et al. Retrospective comparison of first-line adjuvant anthracycline vs metro- nomic-based chemotherapy protocols in the treatment of stage I and II canine splenic haemangiosarcoma. Vet Comp Oncol. 2020;18(1):43-51. doi:10.1111/vco.12548
3. New data from Banfield Pet Hospital reinforces the power of preventive veterinary care. News release. Banfield Pet Hospital. October 14, 2021. Accessed May 27, 2023. www.banfield.com/en/about-banfield/newsroom/press-releases/2021/new-data-from-banfield-pet-hospital-reinforces-the-power-of-preventive-veterinary-care
4. Raoof S, Clarke CA, Hubbell E, Chang ET, Cusack J. Surgical resection as a predictor of cancer-specific survival by stage at diagnosis and cancer type, United States, 2006-2015. Cancer Epidemiol. 2023;84:102357. doi:10.1016/j.canep.2023.102357