February 17, 2026 – Antibiotics have transformed animal health. Infections that once killed pets, horses and wildlife can now be treated quickly and effectively, often with a routine visit to a veterinarian. But that success has created a new and growing problem. Antibiotic resistance is making some infections harder, and sometimes impossible, to treat.
Antibiotic resistance occurs when bacteria change in ways that allow them to survive treatment with antibiotics. When this happens, infections become more difficult to control and treatment options become limited.
In animals, antibiotic resistance can increase the risk of complications, raise the cost and complexity of care, and allow resistant bacteria to spread between animals, people and the environment.
Though antibiotic resistance is part of the broader issue of antimicrobial resistance, which includes resistance to drugs used against parasites and other microbes, this article focuses primarily on bacteria while also addressing emerging resistance in parasites.
Key Points
- Antibiotic resistance happens when bacteria survive treatment and continue to grow.
- Misuse and overuse of antibiotics accelerate resistance.
- Resistant bacteria can spread between animals, people and the environment.
- Research focuses on prevention, better diagnostics and alternatives to antibiotics.
What Are Antibiotics and How Do They Work?
Antibiotics are drugs designed to fight bacterial infections. They work in several ways.
Some antibiotics damage the bacterial cell wall, causing the bacteria to break apart and die. Others prevent bacteria from making essential proteins. Some interfere with how bacteria copy their DNA, stopping them from multiplying.
Antibiotics do not work against viruses or parasites. They will not treat viral infections such as canine influenza or parasitic diseases such as heartworm. Using antibiotics when they are not needed does not help the animal and increases the risk of resistance. These drugs are powerful tools, but only when used carefully and for the right reasons.
How Does Antibiotic Resistance Develop?
Antibiotic resistance is a natural process that accelerates with misuse and overuse.
When an antibiotic is given, most bacteria die. A small number may survive because of genetic traits that protect them. Those survivors multiply. Over time, the antibiotic that once worked well becomes less effective or stops working altogether.
Resistance develops more quickly when:
- Antibiotics are used when they are not needed.
- The wrong drug or dose is prescribed.
- Treatment is stopped too early.
- Resistant bacteria spread between animals, people, and the environment.
Once resistance develops, veterinarians have fewer options. Treatments may become more expensive, more invasive, or less likely to succeed.
Why Does Antibiotic Resistance in Animals Matter to People?
Animals and people share bacteria. Pets live in close contact with their families, sharing homes, surfaces, and daily routines. Horses, livestock, wildlife and people share land, water and ecosystems. Resistant bacteria move easily between species.
Examples include:
- MRSA infections that can spread between pets and people.
- Drug-resistant infections in dogs that limit treatment options and increase the risk of exposure in households.
- Environmental reservoirs of resistant bacteria that affect both animals and humans.
This shared risk is why antibiotic resistance is considered a One Health issue. Animal health, human health, and environmental health are tightly connected.
What Is Morris Animal Foundation Doing About Antibiotic Resistance?
Morris Animal Foundation is a nonprofit organization that funds animal health research worldwide. The Foundation supports studies that look beyond short-term treatment and focus on prevention, early detection and safer alternatives that reduce reliance on antibiotics.
Alternatives to Traditional Antibiotics
These studies explore new ways to treat infections without contributing to resistance.
- Testing a novel compound to treat foal pneumonia without promoting resistance
- Investigating new antimicrobial strategies for urinary tract infections
Understanding Resistance in Serious Bacterial Infections
This work examines how resistance develops in high-risk, hard-to-treat diseases.
Limiting Spread Between Animals, People, and Environments
Transmission is where resistance can accelerate quickly, making prevention critical.
- Controlling the spread of antibiotic-resistant staph infections
- Understanding MRSA transmission between humans and pets
- Understanding transmission risk between therapy dogs and children with cancer
Understanding How Bacteria Behave and Adapt
Foundational research into bacterial behavior can reveal new ways to disrupt infection.
Addressing Drug Resistance in Parasites
Drug resistance is also emerging in parasites, reducing the effectiveness of treatments that protect animal health.
- Designing a novel heartworm vaccine
- Blocking heartworm transmission
- Improving diagnostics for drug-resistant parasites in horses
- Identifying drug-resistant parasites across animal species
Together, these projects reflect a shift toward smarter prevention, better diagnostics, and alternatives that protect animal health while preserving lifesaving drugs.
What Published Research Shows
Research supported by Morris Animal Foundation is contributing to a growing body of evidence on how resistance develops and how it can be slowed. These findings help veterinarians, researchers and public health experts make better decisions in real-world settings.
- Antibiotic use patterns in dogs: Data from the Golden Retriever Lifetime Study provides insight into how antibiotics are used across thousands of dogs, helping identify opportunities for better stewardship.
- Environmental factors in MRSA transmission among pets: Research shows how shared environments influence the spread of resistant staph infections between animals and people.
- New approaches to treating canine urinary tract infections: Studies suggest alternative therapies may reduce antibiotic use while still effectively managing common infections.
- Scientific studies on antimicrobial resistance mechanisms: Peer-reviewed publications funded in part by Morris Animal Foundation examine how bacteria adapt, communicate, and persist in animals and shared environments, reinforcing the need for prevention-focused and non-antibiotic strategies.
https://www.mdpi.com/2079-6382/13/2/130
https://journals.asm.org/doi/10.1128/mra.00735-19
https://journals.asm.org/doi/pdf/10.1128/msphere.00033-19
https://link.springer.com/article/10.1186/s40168-014-0052-7
What Pet Owners and Caregivers Can Do
Everyone has a role in slowing antibiotic resistance.
- Use antibiotics only when prescribed by a veterinarian.
- Follow dosing instructions carefully and complete the full course.
- Never share medications or use leftovers.
- Keep animals up to date on preventive care, including parasite prevention.
- Practice good hygiene, especially when caring for sick animals.
- Ask questions about why a treatment is recommended.
Why Continued Research Matters and How You Can Help
Antibiotic resistance will not be solved by a single discovery. It requires steady, well-designed research and a commitment to long-term solutions. Each study builds knowledge that helps veterinarians make better decisions and protects animals from infections that are becoming harder to treat.
When you support Morris Animal Foundation, you help sustain the research veterinarians rely on every day to care for animals safely and effectively. Your donation supports science that improves how antibiotics are used, identifies resistance earlier, and develops safer alternatives when existing drugs fall short, ensuring effective treatments remain available for the animals who depend on them now and in the future.
