The technology at the heart of the study is the OncoK9 test, a multi-cancer early detection assay developed by PetDx and clinically available for dogs since 2021. The test exploits the biology of circulating tumor DNA: as cancer cells grow and die, they shed fragments of DNA into the bloodstream. These cell-free DNA fragments carry somatic genomic alterations, acquired mutations and chromosomal changes that are hallmarks of malignancy. Using next-generation sequencing on blood drawn from a jugular or peripheral vein, the assay reads these fragments, aligns the sequences against the canine reference genome CanFam3.1, and applies custom bioinformatics pipelines to distinguish cancer-associated signals from background genomic noise. A result is returned to the veterinarian within seven to fourteen days, typically as a binary call: Cancer Signal Detected or Cancer Signal Not Detected.

Enrollment began in December 2021 under two institutional animal care protocols spanning 24 clinical sites across the United States and Canada, a mix of 21 general practices, two academic institutions and one specialty center. In total, 725 presumed cancer-free dogs joined the study, most of them classified as being at increased risk for cancer based on age, breed or body weight. Dogs aged seven years or older were eligible regardless of breed, as were younger dogs belonging to breeds with elevated lifetime cancer risk, and the cohort ranged in age from 1.75 to 20.2 years with a median of 8.4 years. Golden Retrievers dominated the breed list with 68 enrolled dogs, followed by Labrador Retrievers, German Shepherd Dogs, Boxers and Rottweilers. At each routine follow-up visit, conducted annually or every six months depending on the protocol, dogs received a complete physical examination and a blood draw of 14 to 17 milliliters collected into specialized tubes that keep cell-free DNA stable at ambient temperature for a week, requiring no refrigeration or immediate processing.

The first interim analysis focused on the 419 dogs that had been enrolled for at least a year with two or more screening visits, or that had received a cancer diagnosis while on study, with a mean observation period of 422 days. Within this group, 51 dogs were newly diagnosed with cancer, 37 with definitive diagnoses confirmed by pathologist-reviewed histopathology or cytology and 14 with presumptive diagnoses. The most common anatomic locations of disease were the liver, skin, bone, heart, spleen, lung and lymph nodes, a distribution that underscores why genomic screening matters: many of these cancers arise deep within the body where physical examination alone cannot detect them until they are advanced.

The performance metrics of the liquid biopsy test paint a nuanced picture. Of the 51 cancer-diagnosed dogs, 29 received a Cancer Signal Detected result, yielding an observed sensitivity, or detection rate, of 56.9 percent. Specificity was strikingly high at 98.9 percent, meaning only four dogs out of 366 that remained cancer-free received a false positive result, a false positive rate of just 1.1 percent. The positive predictive value reached 87.9 percent, indicating that nearly nine out of ten positive screening results were followed by an actual cancer diagnosis, and the negative predictive value was 94.3 percent. Notably, these figures closely match the test’s performance in its earlier clinical validation study and in a retrospective review of more than 1,500 real-world clinical cases, a consistency the authors attribute to the use of independent training and testing sets during validation, a design strategy intended to guard against statistical overfitting and inflated performance estimates.

Perhaps the most consequential finding concerns how cancer was actually detected. Under conventional veterinary practice, only 12 percent of the cancers in this cohort, six of 51 cases, were caught preclinically through wellness examinations or routine care alone, a figure consistent with a prior retrospective audit of more than 350 dogs in which just 4 percent of cancers were detected at routine visits. When the NGS-based test was added, workups prompted solely by a detected cancer signal led to the preclinical diagnosis of 22 additional cases, lifting the preclinical detection rate to 55 percent, a 4.6-fold increase. Overall, the test accounted for 26 of the 51 cancer diagnoses, effectively doubling the total number of cancers found in the population during the study period.

The clinical pathway following a positive result proved efficient and accessible. Among the 29 true-positive dogs, 86 percent had their first detected signal at a regularly scheduled visit rather than an unscheduled sick visit, and once a positive result triggered confirmatory evaluation, cancer was typically diagnosed within weeks, with a median time to diagnostic resolution of 23 days. More than half of these dogs reached diagnostic resolution within one month, and 92 percent within six months. Critically, in 27 of the 29 true-positive cases, cancer was localized using the diagnostics recommended in the study’s confirmatory evaluation, comprehensive physical exam, routine laboratory tests, three-view thoracic radiographs and abdominal ultrasound, all procedures commonly available in general practice, with only two dogs requiring advanced modalities such as echocardiography or magnetic resonance imaging. Among the 20 definitively diagnosed true-positive dogs, 14 had localized disease confined to the organ of origin, suggesting the test can identify cancer early enough to offer a genuine therapeutic window.

The study also documented rare false positives and a meaningful fraction of false negatives. The four false-positive dogs all underwent substantial confirmatory workups, including laboratory testing, thoracic and abdominal imaging, and in some cases echocardiography, fine needle aspiration or computed tomography, and none was diagnosed with cancer during continued follow-up. The authors caution, however, that some apparent false positives could represent ultra-early detection: human studies have retrospectively identified cancer-derived DNA alterations in plasma three to four years before clinical diagnosis, and the earlier CANDiD validation study reported detecting tumor-associated alterations five months before a hemangiosarcoma diagnosis in one dog. Longer follow-up, they note, will be needed to adjudicate such cases. Among the 22 false-negative dogs, more than a third carried small skin tumors under two centimeters, masses that the test was never intended to replace physical examination or fine needle aspiration in evaluating, and detection rates are known to vary with tumor size, extent of disease and anatomic location, with aggressive cancers like lymphoma and hemangiosarcoma more readily detectable than anatomically isolated tumors of the bladder, prostate or central nervous system.

Owner and veterinarian acceptance of the screening program was overwhelmingly positive. Of 343 owners who responded to satisfaction surveys, average agreement scores with statements about the value of annual or semi-annual screening hovered around 9.3 to 9.6 on a 10-point scale, and 297 of 343 respondents said they were likely or very likely to pay for recommended screening. Veterinarians rated the clarity of the test reports and their usefulness in clinical management at 9.5 or higher on average, though the survey response rate among clinicians was small, with only 10 of 44 questionnaires returned. Safety data were equally reassuring: of 725 enrolled dogs, just 35 adverse events were reported in connection with blood draws, nearly all minor hematomas or bruising at the venipuncture site, and no adverse events occurred during diagnostic workups prompted by positive results.

The study is not without limitations, and the authors are candid about them. The interim analysis covers a relatively short observation window, and key questions remain unresolved, including whether the optimal screening interval is six or twelve months, whether earlier detection ultimately improves stage-specific survival, and how to account for owners who self-select into longer screening intervals. Because dogs lack a standardized national cancer registry analogous to the SEER program in human oncology, precise canine cancer incidence remains uncertain, making the prospectively documented 12 percent period prevalence in this predominantly high-risk cohort a valuable new data point. The study was funded by PetDx, the test’s developer, and PetDx employees participated in the research. Still, the investigators frame CLASSiC as a milestone: the first evidence that incorporating genomic liquid biopsy into regularly scheduled wellness visits can substantially increase preclinical cancer detection in dogs, achieved with a simple blood collection that any clinical practice can perform, and a foundation for the evidence-based screening guidelines that veterinary medicine has long lacked.

Subject of Research: Prospective cancer screening in dogs using next-generation sequencing-based liquid biopsy

Article Title: The Cancer Lifetime Assessment Screening Study in Canines (CLASSiC): interim results of the first prospective cancer screening study in dogs using next-generation sequencing-based liquid biopsy

Article References: Flory, A., Gray, S., McLennan, L. M., Rafalko, J. M., Marshall, M. A., Wotrang, K., Kroll, M., Flesner, B. K., O’Kell, A. L., Cohen, T. A., Ruiz-Perez, C. A., Sandford, E., Clavere-Graciette, A., Phelps-Dunn, A., Motalli-Pepio, R., McCleary-Wheeler, A. L., Nakashe, P., Cristobal, M. A., Anderson, P., … Grosu, D. S. (2026). The Cancer Lifetime Assessment Screening Study in Canines (CLASSiC): interim results of the first prospective cancer screening study in dogs using next-generation sequencing-based liquid biopsy. Veterinary Oncology, 3(1), Article 12. https://doi.org/10.1186/s44356-026-00062-7

Image Credits: AI Generated

DOI: 10.1186/s44356-026-00062-7

Keywords: canine cancer, liquid biopsy, next-generation sequencing, cancer screening, multi-cancer early detection, cell-free DNA, veterinary oncology, OncoK9, preclinical detection, CLASSiC study, prospective study, pet health

Covering nearly 500 domestic feline tumor samples sourced from five different countries, this study entailed extensive DNA sequencing performed on tissues originally collected for diagnostic purposes by veterinarians. The collaborative effort drew on expertise spanning the Wellcome Sanger Institute, the University of Guelph, the University of Bern, and other leading institutions, heralding a new era of transdisciplinary cancer research. By meticulously analyzing mutational signatures and identifying key cancer-driving genes, the team uncovered striking parallels between the oncogenomes of cats and humans, reaffirming the evolutionary conservation of tumorigenic mechanisms.

Among the pivotal findings is the recurrent mutation in the FBXW7 gene within over half of the feline mammary tumor samples. FBXW7 encodes a crucial component of the ubiquitin-proteasome system, responsible for targeting oncogenic proteins for degradation, and its disruption is well-documented in human breast malignancies as correlating with poor prognosis. The discovery that a similar mutational event occurs prevalently in cats not only reinforces shared molecular pathways but also implicates FBXW7 as a critical oncogenic driver across species.

Further analysis revealed a constellation of driver mutations consistent across diverse tumor types including hematologic, osseous, pulmonary, cutaneous, gastrointestinal, and central nervous system neoplasms. These results emphasize a conserved oncogenic blueprint underlying multiple cancers despite species differences, underscoring the potential influence of common environmental carcinogens impacting domestic animals and their human companions alike. The overlap in mutational landscapes speaks volumes about the co-evolution of cancer biology in shared habitats.

Of particular translational significance, the research team investigated therapeutic susceptibilities in cat mammary tumors harboring FBXW7 mutations. Remarkably, in ex vivo tissue assays, certain chemotherapeutic agents demonstrated heightened efficacy against mutated tumors. Although these findings are preliminary and require clinical validation, they pave the way for precision oncology approaches in feline patients, setting the stage for novel interspecies therapeutic strategies. This cross-pollination of insights hints at a promising “One Medicine” paradigm, wherein veterinary and human oncology can mutually inform and accelerate drug discovery and patient care innovations.

The concept of ‘One Medicine’ champions integrated research that transcends traditional disciplinary boundaries, facilitating a continuous exchange of knowledge between human and veterinary medicine. This international study exemplifies that ethos, demonstrating how comparative oncology can unravel shared genomic drivers of cancer, identify therapeutic targets, and enable the development of treatment modalities applicable to multiple species. Evidence from feline tumors brings invaluable perspectives that could refine human cancer therapies and vice versa, reinforcing the interconnectedness of mammalian health.

Dr. Geoffrey Wood, a pathobiology professor at the University of Guelph and co-senior author, reflects on the transformative potential of this genetic resource. “Before this, the genetic architecture of feline cancers was a complete mystery. With this dataset, we have opened a black box and now hold the keys to detailed molecular understanding that can directly inform diagnostics, prognostics, and therapeutic design.” His insight illustrates the momentum gained in veterinary oncology by harnessing cutting-edge genomic techniques long established in human medicine.

Complementing Dr. Wood’s emphasis, Dr. Sven Rottenberg from the University of Bern highlights the novelty of the drug response data: “Access to a vast repository of donated tissues enabled us to perform unprecedented assessments of chemotherapy efficacy against genetically defined tumor subtypes. This high-resolution pharmacogenomic profiling was simply not feasible before and represents a significant leap for translational research in cats.”

The data also have profound implications for accelerating the detection and management of aggressive malignancies in domestic cats, which remain a leading cause of mortality among pets. By elucidating the molecular drivers of these cancers, veterinarians may soon leverage precision diagnostic tests to stratify patients according to risk and predict therapeutic responses with greater accuracy, improving clinical outcomes and quality of life for feline patients.

Moreover, these insights echo far beyond feline health, as domestic cats frequently share environments with their owners, encountering similar carcinogenic exposures. Identifying shared mutagenic agents and understanding their mechanistic roles across species has the potential to refine public health interventions aimed at mitigating cancer risk in humans and animals alike.

The study further opens the door to innovative clinical trial designs that incorporate domestic cats as biomedical models. Given their spontaneous tumor development and diverse genetic backgrounds, cats may serve as invaluable intermediaries between rodent models and human trials, enhancing predictive validity and facilitating safer, more effective anti-cancer therapeutics.

Looking ahead, the authors envision an exciting future where the integration of oncogenomic data with clinical veterinary practice ushers in an era of precision feline oncology, parallel to advances realized in canine cancer treatment. This will necessitate continued investment in genomic infrastructure, inter-institutional collaborations, and the expansion of biobanking initiatives to capture the heterogeneity of feline cancers worldwide.

This transformative body of work, partly funded by EveryCat Health Foundation, CVS Group, Wellcome, the Natural Sciences and Engineering Research Council of Canada, and the Swiss National Science Foundation, represents a milestone in both veterinary and comparative oncology. By unveiling the oncogenome of the domestic cat, it equips the scientific community with a robust foundation to confront cancer with unified resolve across species boundaries.

Subject of Research: Animal tissue samples
Article Title: The oncogenome of the domestic cat
News Publication Date: 19-Feb-2026
Web References: http://dx.doi.org/10.1126/science.ady6651
Image Credits: University of Guelph
Keywords: feline cancer, oncogenome, FBXW7 mutation, comparative oncology, precision medicine, veterinary pathology, domestic cat tumors, cancer genetics, chemotherapeutic efficacy, One Medicine approach

Charles A. Maitz, an associate professor of radiation oncology at the University of Missouri’s College of Veterinary Medicine, highlights the transformative impact of integrating radiopharmaceuticals with advanced imaging technologies. This integration is enabling the veterinary field to transcend traditional diagnostic methods, providing more detailed insights into tumor biology and behavior. As Maitz explains, these advances particularly elevate the understanding and treatment of canine thyroid cancer, supporting a shift toward more individualized therapeutic strategies.

The study’s novelty lies in its exclusive focus on 32 dogs who received radioactive iodine therapy without the confounding effects of surgery or chemotherapy. This approach allowed the research team to isolate the direct effects of iodine-131 treatment. Such a controlled setting is invaluable because it clarifies how the radioactive agent itself influences therapeutic outcomes, a question that has long required deeper exploration in veterinary oncology.

Prior to therapy, each dog underwent specialized nuclear imaging procedures designed to scrutinize the biological characteristics of their thyroid tumors. Imaging modalities such as Single Photon Emission Computed Tomography (SPECT) or Positron Emission Tomography (PET) provide detailed functional maps of radioactive uptake by tissues. Building on this data, the researchers employed radiomics — an emerging computational technique that extracts high-dimensional quantitative features from medical images, revealing data patterns invisible to the naked eye.

Radiomics distinguishes itself from classical image interpretation by leveraging machine learning algorithms and statistical analyses to quantify subtle variations in texture, shape, and intensity within tumor scans. Unlike the subjective evaluations by radiologists, this method delivers an objective, data-rich characterization of tumor heterogeneity and behavior. Maitz notes that harnessing computational power to interrogate pixel-level statistics offers unprecedented clarity into how cancerous tissue differs biochemically and physiologically.

One of the pivotal discoveries from this study was a clear correlation between the dose of radioactive iodine absorbed by the tumor and the efficacy of the treatment. Dogs receiving higher radiation doses exhibited improved response rates, underscoring the critical importance of dose precision. This finding advocates for a paradigm shift in veterinary radiation oncology, where dosimetry—the measurement of radiation actually deposited in target tissues—could replace current dosing practices that rely solely on administrated amounts.

Furthermore, the study uncovered that the clinical condition of the patient and the extent of cancer metastasis markedly influence therapeutic success. Tumor spread to lymph nodes and beyond negatively impacted long-term survival, while the relative uptake of radiation by tumors compared to adjacent tissues, such as salivary glands, played a significant role. These insights emphasize the complexity of thyroid cancer’s biologic behavior in dogs and the necessity of comprehensive pre-treatment assessments.

This research exemplifies a translational model of oncology, bridging veterinary and human medicine through the comparative oncology framework. Thyroid cancer treatment using radiopharmaceuticals has a storied history in human medicine spanning nearly seven decades, and about fifty years in canine patients. The dual perspective enriches understanding of both species’ disease mechanisms and treatment responses, fostering cross-disciplinary advances.

Maitz also holds a research position at the University of Missouri Research Reactor (MURR), an institution pivotal in radiopharmaceutical development. MURR’s unique infrastructure enables the synthesis of radioactive compounds under stringent conditions, allowing researchers to tailor radiotracers specifically for diagnostic and therapeutic purposes. This collaboration facilitates cutting-edge veterinary clinical trials and propels forward radiopharmaceutical innovation domestically.

Harnessing MURR’s capabilities alongside Mizzou’s interdisciplinary environment—integrating chemistry, small animal medicine, advanced imaging, and drug design—positions this team at the forefront of radiopharmaceutical research. Maitz envisions leveraging naturally occurring cases of canine thyroid cancer as a testbed for optimizing radiotracers and dosing protocols, ultimately accelerating the pipeline from veterinary application to human clinical trials.

Employing sophisticated imaging tools to monitor and quantify the biodistribution of radioisotopes in real time allows the researchers to model radiation dose and predict biological effects more accurately. This dynamic feedback loop not only enhances therapeutic precision in pets but also serves as a blueprint for refining radiation-based treatments in human oncology, illustrating the profound ripple effects of veterinary research.

The landmark paper detailing these findings, titled “Prognostic Role of Patient, Tumour and Radiomic Factors Influencing Outcomes in Dogs With Thyroid Cancer Treated With Iodine-131,” was published in the esteemed journal Veterinary and Comparative Oncology. This multidisciplinary study features contributions from experts at Mizzou, Massachusetts General Hospital and Harvard Medical School, as well as the University of California, Berkeley, exemplifying a collaborative and translational research ethos.

This pioneering work heralds a new era in veterinary cancer care, where precision dosimetry, advanced imaging analytics, and radiopharmaceutical innovation converge. As the veterinary and medical communities digest these advancements, the promise of extending life and improving quality of life for dogs suffering from thyroid cancer becomes increasingly tangible. Beyond pets, these developments foreshadow transformative impacts for human thyroid cancer therapies, reinforcing the vital interconnections between animal and human health sciences.

Subject of Research: Canine thyroid cancer treatment using radioactive iodine therapy and radiomics analysis.

Article Title: Prognostic Role of Patient, Tumour and Radiomic Factors Influencing Outcomes in Dogs With Thyroid Cancer Treated With Iodine-131.

News Publication Date: 4-Jun-2025.

Web References:
https://doi.org/10.1111/vco.13070

References:
Cowan C., Donnelly L., Chamseddine I., Schuemann J., Bertolet A., Abergel R.J., Maitz C.A. (2025). Prognostic role of patient, tumour and radiomic factors influencing outcomes in dogs with thyroid cancer treated with Iodine-131. Veterinary and Comparative Oncology.

Keywords: Veterinary medicine, Animal health, Thyroid cancer, Radiopharmaceuticals, Radiomics, Nuclear imaging, Dosimetry, Comparative oncology, Iodine-131, Canine cancer, Personalized treatment, Radiology.