Biomarkers provide key clues for diagnosing, treating veterinary patients

Biomarkers have long been part of the veterinarian's toolbox, but how they are being used today is expanding rapidly.

Once considered adjuncts to traditional diagnostic methods, data gleaned from biomarkers are now helping clinicians detect common health conditions earlier, refine diagnoses and treatment plans, track disease progression, and even predict outcomes. Across specialties, researchers and clinicians are uncovering innovative ways to integrate these tools into daily practice.

So, what exactly is a biomarker? In simple terms, it's a measurable sign of what is happening inside the body—an objective indicator of normal function, disease, or response to therapy. Broadly defined by the National Institutes of Health Biomarkers Definition Working Group in 1998, even standard clinical measurements like pulse rate could qualify as biomarkers. In practical terms, however, the word usually refers to substances in body fluids or tissues—such as proteins, hormonse, metabolites, or genetic markers—that can be measured and analyzed to provide valuable clinical insight.

Examples of biomarkers in action span the breadth of veterinary medicine, across species and disciplines. Some of the more promising and emerging applications are in veterinary cardiology, oncology, orthopedics, and nephrology.

Detecting and distinguishing heart disease

In veterinary cardiology, interest has been growing in the use of biomarkers to detect heart disease in various stages, as well as to understand prognostication and response to treatment, says Dr. Darcy Adin, associate dean of clinical services and small animal clinical professor of cardiology at the University of Florida College of Veterinary Medicine.

Two biomarkers in particular, cardiac troponin I and N-terminal-pro B-type natriuretic peptide (NT-proBNP) have been used as an aid in diagnosing and treating heart disease in dogs and cats, she noted. And research continues to uncover ways that these markers can be used to improve accessibility, support early diagnosis, and understand disease progression

Cardiac troponin I is a protein that is released when heart muscle cells are injured or die, and BNP is a hormone excreted in response to stretching of the myocardium that splits into an active form and an inactive form (NT-proBNP). The inactive form is measured to detect myocardial stretching.

Testing for cardiac troponin I or NT-proBNP can be performed by a veterinary diagnostic laboratory or on-site using a point-of-care device validated for use in animals. The appropriate sample type depends on the test and may include serum or plasma.

Another application for NT-proBNP, she says, is using it to determine whether breathing problems in cats are due to heart failure or a respiratory issue.

"In a situation where a dyspneic cat is not stable enough for an echocardiogram, a SNAP NT-prBNP can guide the veterinarian toward appropriate emergency treatment of either congestive heart failure if positive or respiratory disease if negative," she notes.

"There are numerous applications of NT-proBNP and cardiac troponin I to help understand cardiac diseases in dogs and cats," Dr. Adin adds.

Screening for cancer

At Cornell University, a novel biosensor device being developed Roy Cohen, PhD, and Dr. Alex Travis to detect strokes in humans is also being studied as a potential tool to screen dogs at risk of hemangiosarcoma. The tethered enzyme technology (TET) sensor uses silica nanotechnology to detect several types of biomarkers, including proteins, metabolites, and nucleic acid.

The study was initially supported by Cornell's Baker Institute for Animal Health, and Drs. Cohen and Travis then began collaborating with Scott Coonrod, PhD, also at Cornell, who was researching micro-RNA biomarkers of hemangiosarcoma.

In an unpublished pilot study of 50 dogs, a micro-RNA showed promise in diagnosing hemangiosarcoma. With additional funding from Cornell's Richard P. Riney Canine Health Center and working with Dr. Skylar Sylvester from Cornell's College of Veterinary Medicine, they tested patient blood samples to further optimize the TET device for detection of hemangiosarcoma-associated microRNA in plasma in less than five minutes.

The researchers' first goal is to develop a diagnostic test. They also hope to develop a simpler version of the technology that can be used to routinely screen dog breeds prone to hemangiosarcoma.

"With early detection, surgery or chemotherapy would actually help and many dogs could be saved," says Dr. Cohen.

When funding is available, the research team plans to conduct a larger multicenter study to validate the results.

The Cornell researchers are also investigating whether the TET sensor can be used to identify biomarkers for brain injuries in dogs. Such testing could be used to determine whether gait abnormalities in dogs are due to neurological issues, Dr. Cohen said. A second-phase pilot study involving about 30 dogs is currently underway.

Preventing catastrophic injuries in equine medicine

At the University of Pennsylvania School of Veterinary Medicine, equine researchers are studying how biomarkers might be used to identify racehorses at increased risk of serious leg injuries. For the past eight years, researchers at the veterinary school’s Equine Pharmacology Laboratory (EPL) have been collecting blood samples from racehorses to develop a biobank for longitudinal studies of racehorse health, explains Dr. Joanne Haughan, the laboratory's research project manager.

In a preliminary study looking at the relationship between certain biomarkers and fetlock injuries, EPL investigators compared protein osteocalcin and C-terminal telopeptide 1 (CTX-1) concentrations in blood samples of six racehorses during the first six months of training. Three of the horses developed pathological fetlock changes and three did not. The study, which was presented at the 2023 American College of Veterinary Surgeons' Surgery Summit, indicated that blood osteocalcin concentrations were significantly lower in the horses with pathological fetlock changes. The study findings are currently being validated in a larger study of 41 horses.

"Our goal is to identify things we could potentially find in the horse's blood that would indicate they need more testing, imaging, and need to be monitored more closely by a veterinarian at the track," said Dr. Haughan. "The long-term goal is to have these types of biomarkers as an initial screening tool because they are cheaper and less invasive than other modalities, but they would always need to be backed up by clinical examinations and imaging findings."

Kidney disease: Refining diagnoses and reducing the need for biopsies

The use of biomarkers to diagnose kidney diseases in dogs and cats also is growing. While biomarkers like serum creatinine concentration have long been used to assess kidney function, other biomarkers that provide more details are being studied and applied in clinical practice.

At Texas A&M University College of Veterinary Medicine & Biomedical Sciences, pathology researchers have developed a test to separate urine proteins by size. The test, called urine SDS-PAGE, has been offered as a standalone test through the International Veterinary Renal Pathology Service (IVRPS) since 2017. It can indicate whether renal proteinuria in dogs and cats is tubular or glomerular in origin, and can also indicate the extent of the damage, says Dr. Jessica Hokamp, clinical associate professor in clinical pathology and director of IVRPS.

The analysis is done manually and takes two to three weeks to complete, she said. The laboratory currently analyzes about 150 samples a month, up from about 30 samples per year when it first began offering the test.

While the test cannot substitute for a kidney biopsy, it can reduce the need for a biopsy in some patients.

"There are cases where a clinician cannot do a biopsy due to cost, stability of the patient, or lack of expertise. However, often the test provides enough information to warrant empirical therapy and see how the patient responds. Some clinicians opt to monitor SDS-PAGE results over time during empirical treatment," says Dr. Hokamp.

Other renal biomarkers are being studied across the country, but it's difficult to know which tests will end up being brought to market and successfully applied in clinical practice, notes Dr. Mary Nabity. She is Dr. Hokamp's colleague, as an associate department head of clinical services, and interim director of the Texas A&M Veterinary Medical Teaching Hospital's Clinical Pathology Laboratory.

"Many biomarkers have been studied over the past 20 years, such as NGAL (neutrophil gelatinase-associated lipocalin), which is a marker of tubular injury, but whether any of them will ultimately become commercially available tests is hard to say because a lot of factors go into introducing a biomarker to the market," said Dr. Nabity.

The key to using biomarkers, the researchers say, is to remember that, like any tool, it is not perfect. No biomarker will have 100% sensitivity or specificity for a disease, they note, and the results need to be considered holistically in the context of other diagnostic tools such as complete bloodwork, imaging, and physical examinations.

"All of veterinary medicine is a puzzle," says Dr. Hokamp. "The pieces of information we get from the exam, the history, the bloodwork—it all has to go together because we are assessing different aspects of physiology and pathology with each modality that we can't assess with one single test."

Julie A. Jacob is a freelance writer based in Racine, Wisconsin.

A version of this story appears in the January 2026 print issue of JAVMA