MicroRNA blood test research advances canine splenic mass triage: full analysis

A 2025 study in Veterinary Pathology adds fresh evidence that a blood-based microRNA assay could help veterinarians assess canine splenic masses before the scalpel. The paper, from investigators at the University of Guelph and the University of Veterinary Medicine Vienna, found that specific serum and tissue microRNA patterns differentiated splenic hemangiosarcoma from benign splenic masses and from normal dogs, raising the possibility of a less invasive tool for one of small animal practice’s most difficult abdominal cancer calls. (journals.sagepub.com)

That matters because splenic masses in dogs remain a high-stakes diagnostic gray zone. Hemangiosarcoma is a common malignant splenic tumor in older dogs, and many patients present only after rupture, internal bleeding, weakness, or collapse. Ultrasound can localize a splenic mass, but it generally can’t definitively tell clinicians whether the lesion is benign or malignant. In practice, that leaves teams and pet parents making urgent decisions about splenectomy, stabilization, referral, or euthanasia without a firm diagnosis in hand. And the prognostic spread is wide: benign lesions such as hematoma or nodular hyperplasia may be cured with surgery, while splenic hemangiosarcoma still carries a poor median survival of about 6 to 9 months even with chemotherapy. There is also a middle ground of non-hemangiosarcoma malignancies with their own prognoses, which further complicates counseling. The new paper builds on earlier work from 2016 and 2021 showing that microRNA signatures in splenic tissue and serum might distinguish hemangiosarcoma from nodular hyperplasia, hematoma, or healthy controls. (vet.cornell.edu)

In the latest study, investigators profiled 59 microRNAs by RT-qPCR in serum and tissue samples from dogs with hemangiosarcoma, lymphoma, nonangiomatous nonlymphomatous sarcomas, histiocytic sarcoma, benign splenic masses, and normal spleens. The serum cohort included 24 dogs with hemangiosarcoma, 21 with benign splenic masses, and 14 normal dogs, among others; the tissue cohort included 17 hemangiosarcomas and 35 benign splenic masses. The headline result was a five-microRNA serum model, using miR-135a-5p, miR-10a, miR-450b, miR-152-3p, and miR-126-5p, that correctly classified all hemangiosarcoma cases in the study set when compared with normal dogs and dogs with benign splenic masses, with overall accuracy of 86%. A three-microRNA tissue model, using miR-126-5p, miR-502-3p, and miR-452-5p, classified 96% of hemangiosarcoma versus benign mass cases, with all hemangiosarcomas appropriately classified in that comparison. (journals.sagepub.com)

The nuance is just as important as the headline. The serum model did generate false positives among normal dogs, and the authors explicitly frame the work as an early diagnostic and screening foundation, not a clinic-ready standalone test. They also note that confirmation will require prospective samples collected before diagnosis. That caution fits the broader biomarker landscape in canine splenic disease, where prior work on VEGF, imaging characteristics, and multivariable clinical prediction models has shown promise but not enough accuracy to replace surgery and histopathology. In the current paper, the authors argue microRNAs may be most useful when layered onto existing imaging and clinical parameters rather than treated as a single definitive answer. (journals.sagepub.com)

There are also signs the field is moving beyond proof of concept. Cornell has funded work aimed at turning serum microRNA biomarkers into a rapid point-of-care hemangiosarcoma test, including development of a Tethered Enzyme Technology platform and a pilot clinical study at the Cornell University Hospital for Animals. Cornell’s project description underscores the clinical problem directly: today, distinguishing malignant from benign splenic disease often still requires splenectomy and histopathology, even though those decisions are expensive, time-sensitive, and emotionally fraught for pet parents. As study coauthor Janet Grimes noted in an AVMA podcast discussion of the paper, a reliable preoperative test could matter in both directions: it could help avoid overly optimistic counseling in dogs with aggressive disease, but it could also save dogs with benign disease if owners are more willing to pursue surgery and postoperative care when they understand the prognosis may be favorable. (vet.cornell.edu)

Why it matters: If these findings validate prospectively, they could change how general practitioners, emergency clinicians, surgeons, and oncologists triage splenic masses. A dependable blood test could improve conversations with pet parents before emergency surgery, help prioritize referral and staging, and potentially identify some high-risk dogs earlier through senior screening workups. It could also reduce the current reliance on statistics-based counseling in cases where the individual dog’s diagnosis is still uncertain. Just as important, a sensitive preoperative assay might help catch some hemangiosarcomas before rupture, when prognosis is generally better than in dogs first diagnosed after hemoabdomen — while also making it easier for some owners to move forward with potentially curative surgery for benign splenic disease. (journals.sagepub.com)

What to watch: Watch for prospective validation studies, prediagnosis screening data, and whether any point-of-care platform can reproduce these results outside referral-biobank cohorts. Also worth watching is how future models handle the real clinical mix, not just hemangiosarcoma versus benign masses, but lymphoma, histiocytic sarcoma, and other splenic tumors that can complicate the differential diagnosis and create a broad spectrum of prognoses in practice. (journals.sagepub.com)