Recent advances in blood-based cancer screening are beginning to change that paradigm. New screening tools now offer general practitioners a practical way to integrate lymphoma screening appropriately into preventive care and sick-patient diagnostics. By identifying disease earlier than traditional approaches alone, these innovations support more informed clinical decision-making and more timely intervention.

This article outlines how an emerging lymphoma screening approach can be thoughtfully incorporated into practice, with recommended protocols for both clinically well and clinically ill patients.

Why and When to Screen: Identifying At-Risk Canine Patients

A critical point of priority for many clinicians is to ensure we target diagnostics appropriately. With this test, there are two targeted groups of dogs to consider appropriate "at-risk" for cancer:

• All dogs aged 7 years or older.
• All high-risk breeds aged 4 years or older. These include, but are not limited to, the beagle, Bernese mountain dog, boxer, bullmastiff, Doberman pinscher, English bulldog, flat-coated retriever, French bulldog, golden retriever, Labrador retriever, miniature schnauzer, Rottweiler, Scottish terrier, Boston terrier, Chinese pug, German shepherd, Irish wolfhound, Pembroke Welsh corgi, Rhodesian ridgeback, Scottish deerhound, shar-pei, Siberian husky, and Weimaraner.

From a practice implementation standpoint, lymphoma screening can be incorporated into senior canine wellness visits or included in targeted panels for high-risk breeds 4 years of age and older (perhaps as a junior wellness panel). When paired with other preventive screening tests, this approach increases the likelihood of detecting the disease in its early, subclinical stage.

How This New Screening Approach Works

This advancement is a blood test that detects multiple biomarkers specific to canine lymphoma. After development utilizing thousands of canine samples, an internal validation study comparing dogs with confirmed lymphoma to those with other diseases and healthy patients demonstrated:

• Sensitivity of ~79% for confirmed lymphoma cases
• Specificity of ~99% against healthy controls and dogs with other inflammatory or neoplastic diseases

In many positive cases, the test can also provide phenotypic information (B-cell versus T-cell), which is a valuable prognostic indicator that guides therapy.

Additionally, this test provides an accessible screening option for most practices, requiring only 1 milliliter of EDTA whole blood and 2 milliliters of serum. There is no need for additional samples when incorporating this into a wellness screen.

Interpreting Results in Clinically Well Dogs

An industry-wide aspiration has been to implement routine screening in asymptomatic, at-risk dogs during wellness visits. When this screening tool is used during wellness visits, the following framework can help guide next steps.

Result: Not Consistent with Lymphoma

In an otherwise clinically healthy dog, a negative result is reassuring. The recommendation is to re-evaluate at the next scheduled wellness visit. Order further diagnostics only if the patient develops additional clinical signs.

Result: Consistent with Lymphoma

A positive result in an otherwise clinically healthy dog warrants further investigation, including a complete history and physical exam, and if not already performed, foundational database testing (CBC, chemistry, and urinalysis).

There have been documented cases where lymphoma was confirmed by means other than routine physical examination and blood work on follow up. Further evaluation to confirm presence of disease may also be considered, including the following:

• Aspirates or biopsy of lymph nodes/organs
• Diagnostic imaging (chest radiographs and abdominal ultrasound)
• Flow cytometry of blood in cases of lymphocytosis

If lymphoma is not detected, perform a recheck physical exam in 8-12 weeks (or sooner if new symptoms arise). However, if you note any concerning clinical signs or lab abnormalities, the patient should be treated as a clinically ill dog. Clinical signs to watch for include the following:

1. Enlarged lymph nodes on palpation
2. Polyuria/polydipsia with hypercalcemia
3. Gastrointestinal signs (vomiting, diarrhea, weight loss)
4. Bilateral uveitis
5. Moderate-to-marked lymphocytosis
6. Elevated SDMA without concurrent creatinine increase
7. Fever of unknown origin

This protocol ensures that a "positive but clinically healthy" result does not lead to overly aggressive diagnostics by carefully balancing early detection with appropriate monitoring.

Interpreting Results for Clinically Ill Dogs

This bucket includes dogs with clinical signs suggestive of lymphoma, such as lymphadenopathy, weight loss, lethargy, vomiting/diarrhea, respiratory signs, bicytopenias, and hypercalcemia.

Result: Consistent with Lymphoma

This finding supports a clinical diagnosis of lymphoma. Classic staging should follow: imaging (thoracic radiographs and abdominal ultrasound), assessment of regional lymph node or organ involvement, and diagnostics for further characterization including cytology or biopsy of enlarged lymph nodes, organs, or masses to determine exact subtype.

Once the diagnosis is confirmed, consider an oncology referral and/or initiate therapy or management based on the phenotype (B-cell vs. T-cell), disease stage, and clinical picture.

Result: Not Consistent with Lymphoma

Although the result is negative, it does not definitively rule out lymphoma. Next steps are guided by the clinical case and clinician suspicion between 'not consistent with lymphoma' and 'inconsistent with lymphoma but still of high concern.'

If a clinician's suspicion remains high due to persistent lymphadenopathy, cytopenias, or abnormal imaging, continue the diagnostic workup for lymphoma as described above.

If the clinician's suspicion wanes or other differential diagnoses become more likely, the workup should shift towards different causes of the patient's clinical signs (e.g., inflammatory disease, infection, other neoplastic conditions).

Additional Clinical Considerations

This screening tool can add meaningful clarity to clinical decision-making, and understanding its performance characteristics is essential for integration into everyday practice.

False Positives/False Negatives

With a sensitivity of approximately 79% and specificity of approximately 99%, false negatives are possible, particularly in early or atypical disease. False positives can occur, though they are rare.

Phenotyping

Phenotyping provides a valuable advantage and is currently available for approximately 56% of positive results.

Confirmation

This screening approach is designed as a decision‑support and early‑detection tool, not a replacement for cytology or histopathology. A positive result should always be confirmed with diagnostic testing before beginning treatment. This is especially important when the patient appears clinically healthy, as the screening may be the first indication that additional investigation is warranted.

The Clinical Value of Early Detection

More and more clinicians strive for proactive, early disease detection, as it can often positively and profoundly impact patient outcomes. Early detection may allow more time to stage the disease and more treatment options due to less aggressive disease at diagnosis.

Integrating emerging cancer screening tools into general practice, whether as part of screening profiles for at-risk healthy dogs or for the ill patient with unexplained clinical signs, supports the shift in our paradigm from reactive, late-stage lymphoma diagnosis to proactive, guided diagnostic and therapeutic intervention.