When COVID-19 swept the globe, the public spotlight fixated on hospital ICUs and medical researchers. Yet, behind the scenes, a different group of scientists had already been battling similar threats for decades at the animal-human interface.
Walk into any veterinary clinic, and you'll see pets being vaccinated and cared for. But the role of veterinarians extends far beyond these clinical walls—they are frontline defenders in a global battle against pandemics. The COVID-19 crisis offered a stark lesson: while 70% of emerging infectious diseases originate from animals, the veterinary professionals who manage these threats at their source were largely absent from the public narrative, at least in some countries like Italy 5 . This article explores how the quiet, consistent work of veterinary medicine—from vaccinating livestock to monitoring wildlife—forms an invisible shield that protects global human health every day.
At the heart of modern preventive veterinary medicine lies the One Health concept—a recognition that the well-being of humans, animals, and ecosystems are inextricably linked 9 . This isn't a new idea; it has been known for over a century that pathogens don't respect the boundaries between species 9 .
Think of it as a biological chain reaction: climate change and habitat disruption alter wildlife patterns; animals are forced into closer contact with human populations; viruses jump species; and suddenly, a local outbreak becomes a global crisis. Veterinarians are positioned at the crucial intersection of these events, monitoring disease patterns in animal populations long before they appear in humans 5 .
of emerging infectious diseases originate from animals
years since the One Health concept was first recognized
The COVID-19 pandemic perfectly illustrated this interconnectedness. While the world focused on human transmission, veterinarians were investigating cases of SARS-CoV-2 in cats, dogs, farmed mink, and even white-tailed deer 5 . These animal reservoirs mattered—in one documented case, a highly divergent SARS-CoV-2 lineage found in deer eventually made its way back to humans 5 . This phenomenon of viruses bouncing between species and potentially evolving into new variants underscores why monitoring animal health isn't just about protecting animals—it's about protecting ourselves.
Veterinary Public Health (VPH) represents the operational arm of the One Health approach. Far from being just an administrative service, VPH is a dynamic field encompassing population medicine, progressive food safety systems, and animal welfare 1 . Imagine a world where veterinarians only treated individual sick animals but didn't develop vaccination programs, inspect meat, or track diseases in wildlife—our food supply would be less secure, and pandemic risks would skyrocket.
Routine monitoring of domestic animals, livestock, and wildlife to detect potential disease outbreaks before they spread to human populations.
Ensuring the safety of our food supply from farm to table, preventing the transmission of diseases through animal products.
Employing advanced disease-tracking methods developed in animal populations that can be directly applied to human outbreaks.
| Domain | Key Functions | Public Health Impact |
|---|---|---|
| Disease Surveillance | Monitoring zoonotic agents in animal populations | Early warning system for potential human outbreaks |
| Food Safety | Inspection, vaccination programs, food processing oversight | Prevention of foodborne illnesses and zoonotic disease transmission |
| Epidemiology | Disease pattern analysis in animal communities | Informs outbreak modeling and intervention strategies for human diseases |
| Antimicrobial Resistance | Monitoring and optimizing antimicrobial use in animals | Preserves effectiveness of antibiotics crucial for human medicine |
| Wildlife Health | Ecosystem health assessment and wildlife disease monitoring | Identifies environmental factors that increase zoonotic disease risk |
Despite these critical functions, VPH often faces a visibility challenge. In developed countries, there's frequently a lack of student interest in this field, perhaps because the success of preventive measures makes the threats seem distant 1 . Yet as one editorial noted, "VPH is responsible for the entire local animal population and must be adapted and adaptable to changing regional circumstances" 1 .
A cornerstone of effective veterinary research—which directly benefits human medicine—is ensuring animal welfare while maintaining scientific rigor. Historically, assessing animal suffering during experiments relied on subjective scoring, creating inconsistency and raising ethical concerns. This changed dramatically with the development of the RElative Severity Assessment (RELSA) procedure 7 .
German scientists created RELSA to establish an evidence-based method for quantifying severity in laboratory animals. The procedure uses objective, measurable outcomes rather than subjective impressions 7 .
Researchers gather six specific parameters from mice: body weight, burrowing behavior (a natural digging activity that decreases when animals are unwell), heart rate, heart rate variability, temperature, and overall activity.
Data from a standard surgical procedure (transmitter implantation) officially classified as "moderate" severity created a baseline for comparison.
A sophisticated computational algorithm analyzes all six parameters together, generating a single RELSA score that represents the overall welfare state of the animal.
The research established four distinct severity thresholds based on RELSA scores, from mild (L1: <0.27) to severe (L4: <3.45) 7 .
This method allowed researchers to compare suffering across different animals, treatments, and even entirely different disease models—something previously impossible with subjective assessments.
The RELSA procedure yielded remarkable precision in quantifying animal suffering. When applied to various experimental conditions, it produced an evidence-based ranking of severity: sepsis > surgery > restraint stress > colitis 7 .
| Severity Level | RELSA Score Threshold | Example Experimental Conditions |
|---|---|---|
| Mild (L1) | <0.27 | Minor interventions with transient effects |
| Moderate (L2) | <0.59 | Standard surgical procedures (e.g., transmitter implantation) |
| Substantial (L3) | <0.79 | Significant inflammatory conditions (e.g., colitis) |
| Severe (L4) | <3.45 | Life-threatening conditions (e.g., sepsis) |
The power of RELSA lies in its multidimensional approach. By combining multiple variables, it minimizes information loss when one parameter is missing and creates a comprehensive picture of animal welfare that accounts for the complex nature of suffering.
The advancement of veterinary science and its contributions to public health depend on sophisticated research tools. Here are some key reagents and materials used in the field, particularly in developing countermeasures against infectious diseases.
| Tool/Reagent | Primary Function | Application Example |
|---|---|---|
| Synthetic Genes (gBlocks) | Provide DNA blueprint for pathogen proteins | Rapid production of viral proteins for antibody development before live pathogen is available 8 |
| Nomad Single-Pot Library | Semi-synthetic collection of nanobodies (single-domain antibodies) | Selection of specific binders for SARS-CoV-2 nucleocapsid protein within days 8 |
| Reporter Fusion Proteins (e.g., mNeonGreen, mScarlet-I) | Generate inherently fluorescent antibodies | Creation of sensitive imaging tools for visualizing viral infection in cells 8 |
| Peptones (Animal & Plant-Derived) | Nutrient sources for vaccine fermentation | Support microorganism growth during vaccine production; critical for yield and efficacy 9 |
| COVID-AMD Database | Centralized repository of coronavirus animal model data | Enables researchers to identify appropriate animal models for studying CoV infections |
The COVID-19 pandemic demonstrated the critical importance of having such tools ready. Researchers were able to begin developing immunoreagents against SARS-CoV-2 using synthetic genes before the virus itself was even available in their laboratories 8 . This proactive approach exemplifies how veterinary and medical science can work ahead of emerging threats rather than merely reacting to them.
The lesson from COVID-19 and other zoonotic threats is clear: prevention is exponentially more effective and economical than reaction. The World Organisation for Animal Health has compiled essential competencies that veterinarians need to support national veterinary services, and countries like Ethiopia have implemented new national curricula in response 1 . However, barriers remain—including organizational challenges, lack of teaching materials, and financial constraints 1 .
Establishing the One Health concept in both human and veterinary medicine curricula 1
As one editorial emphasized, "Diseases do not recognize borders, so contact between neighbors is a basic condition for successful veterinary measures" 1
Supporting veterinary field staff at all levels with training and resources 1
Utilizing tools like the COVID-AMD database, which catalogs 869 animal models across 29 species, to accelerate research
When we vaccinate a cow against Brucellosis, we're not just protecting that animal—we're preventing Bang's disease in humans. When we monitor influenza in birds, we're not just protecting poultry—we're gathering intelligence that might prevent the next human pandemic. This is the profound, often invisible, work of veterinary medicine.
As we face growing challenges from climate change, habitat destruction, and global interconnectedness, the wisdom of the One Health approach becomes increasingly urgent. The silent shield of veterinary medicine doesn't just make our world safer for animals—it makes it safer for all of us. The next time you see a veterinarian, remember: you're not just looking at an animal doctor, you're looking at a frontline public health professional.