Animal Vaccine FAQs: Protecting Pets, Livestock and Wildlife
Vaccination is a cornerstone of preventive health care and one of the most effective ways to maintain an animal’s health and quality of life. Vaccines prevent animal suffering and death from infectious diseases, support the conservation of biodiversity and strengthen global food and economic security. It is estimated that more than are zoonotic and can spread from animals to people, highlighting an inextricable link between human and animal health.
Human and animal health have always been closely intertwined. In fact, the word “vaccine” was derived from vacca, the Latin word for cow, in reference to the first successful vaccine, which protected people from smallpox and was made from the cowpox virus by .
This FAQ outlines questions about veterinary vaccines and their role in protecting the health of animals, people and the planet.
Veterinary Vaccines: The Basics
Why Is Vaccinating Animals Important?
Vaccines protect pets, livestock and wildlife from life-threatening diseases. For pet owners, this means fewer medical emergencies and healthier companions. For farmers, vaccinating livestock protects entire herds and flocks, safeguarding food supplies and preserving family livelihoods. On a public health level, vaccinating animals decreases the risk of zoonotic diseases transmitted from animals to humans. It also reduces the need for antibiotic treatments, which prevents increasing antimicrobial resistance in animals and people.
How Does Animal Vaccination Work?
Just like in humans, vaccines train an animal’s immune system to recognize and fight disease. Vaccines introduce a small, safe piece of a disease-causing organism into an animal’s body (also called an antigen). The immune system then recognizes the antigen as a threat and triggers an immune response, including activating immune cells and antibody production. This response builds memory in the body for how to respond should the host come in contact with the pathogen in the future. When enough animals in a population are vaccinated, the spread of disease can slow or, potentially, stop altogether.
How Are Veterinary Vaccines Tested for Safety and Effectiveness?
Veterinary vaccines go through years of careful research and testing before they are available for use. On average, the development process takes , depending on the country, technology and target species. National —such as the in the U.S. or the in the European Union—set strict guidelines and require laboratory studies, safety trials and field testing to confirm safety and effectiveness. After approval, vaccines continue to be monitored for adverse side effects, which are rare, generally occurring in . Mild symptoms, like , are more common and indicative that the vaccine is taking effect. These side effects usually go away within 24 hours.
What Types of Vaccines Are Used in Animals?
Most licensed veterinary vaccines today are:
- Live-attenuated: a vaccine containing an intact but weakened (or attenuated) pathogen, which stimulates an immune response but does not cause disease. Because these vaccines introduce an intact microorganism that is most similar to the natural pathogen they are immunizing against, live-attenuated vaccines create a strong and long-lasting immune response and usually require only 1 injection. Examples include vaccines to protect cattle against and all vaccines.
- Inactivated: a vaccine containing a killed (or inactivated) pathogen that is no longer infectious. These vaccines usually don’t provide as much protection as live vaccines, so to maximize their effectiveness. Examples include the , and most .
- Toxoid: a vaccine that uses an inactivated toxin produced by a pathogen. These vaccines stimulate immunity and protect the animal against toxins such as , caused by Clostridium tetani. They are often administered in horses as well as sheep, goats and cattle.
- Recombinant: a vaccine made by inserting DNA encoding an antigen, such as a bacterial surface protein, into another source (often a plasmid expressed in yeast or bacteria). These microbial cells produce the antigen in large quantities, which is then purified for use as the vaccine. Once administered, the purified antigens stimulate the production of antibodies specific to the vaccine antigen. Because of their targeted design, recombinant vaccines than other vaccine types. Often, they also require . Examples include the vaccine for , the leading cause of virus-associated deaths in cats.
Looking ahead, mRNA vaccines, which produce proteins to trigger an immune response, are . They can be developed rapidly, target specific pathogens, be adapted to emerging variants and stimulate strong immune responses in animals. , a vaccine that utilizes the neuraminidase (NA) protein to vaccinate pigs against influenza strains H1N1, H1N2 and H3N2, was launched in 2024 in the U.S. Additionally, Merck Animal Health announced the release of , the first and only mRNA vaccine that safeguards dogs against the threat of canine flu, and , the only non-adjuvanted FeLV vaccine built on RNA particle technology. Despite this promising outlook, shifts in U.S. could slow the pace of veterinary mRNA vaccine development.
What Barriers Do Owners Face When It Comes to Vaccinating Their Animals?
Despite being one of the most effective tools to prevent disease, animal vaccines remain underutilized. Several factors contribute to this gap. In many rural or low-income areas, especially among livestock farmers, . Financial barriers are another hurdle—pet vaccines are typically paid out-of-pocket, and pet insurance is not widely used. In the U.K., cite cost as the reason for skipping vaccines. For smaller-scale farms, competing expenses can make preventive care feel less urgent, even though it protects long-term livelihoods.
Infrastructure also matters: in countries that lack strong animal health systems and have few government veterinarians and limited surveillance capacity, it can be . Access to veterinary care and vaccination services can be , and and misinformation may discourage owners from vaccinating at all. Improving uptake requires a , including vaccine education, fostering public–private partnerships to build stronger infrastructure and offering subsidies or incentives for priority and repeat vaccinations.
In This Issue
- The Link Between Pets, People and Antimicrobial Resistance
- Shedding Light on the Vibrio-Squid Symbiosis
- Baiting Mice to Beat Lyme Disease
- Skin Deep: How Bd and Bsal Fungi Threaten Amphibian Health
- Food Biosecurity: Flyways, Flocks, CAFOs and Avian Flu
- How FMTs, Coprophagia and the Milk Microbiome Inform Wildlife Conservation With Sally Bornbusch
- Animal Vaccine FAQs: Protecting Pets, Livestock and Wildlife
- New World Screwworm: Rise, Fall and Resurgence
- Is a Future Without Animal Models Possible?
Vaccines and Companion Animals
What Vaccines Does My Pet Need?
Vaccine schedules vary based on a pet's age, environment and lifestyle. Veterinarians classify vaccines into 2 categories: core and non-core. Core vaccines are recommended for all pets due to the severity of the diseases they prevent, the risk of exposure and their potential to be transmitted to humans. Some examples include the rabies vaccine, cat vaccines for feline calicivirus and FeLV and dog vaccines for distemper, parvovirus and leptospira. Non-core vaccines are recommended for certain pets based on their individual risk factors. For example, if your dog is often in daycare, boarding or training facilities, they are more likely to be recommended Bordetella and canine influenza vaccines. A veterinarian can advise what non-core vaccines your pet should receive.
How Often Does My Pet Need to Be Vaccinated?
Babies get their first disease protection from their mother’s milk (the colostrum) in the first hours after birth, but this temporary immunity fades quickly. This is why young , followed by a series of booster shots to build lasting immunity. Once the initial vaccine series is complete, some vaccines can protect your pet for several years. For instance, generally last around 3 years for adult pets, while others require more frequent boosters to maintain protection, such as those for . The exact schedule depends on the type of vaccine, your pet’s age and their risk of exposure. Staying on top of the schedule for primary doses and booster shots is important to make sure your pet is fully protected.
Different states, regions and countries also have their own laws governing the administration of certain vaccines, like the rabies vaccine. Some areas require yearly rabies vaccination due to an increased risk of encountering the disease; alternatively, lower-risk regions where the disease is less common require it every 3 years. If you’re traveling to another country with your pet, most countries require pets to arrive with a issued by veterinarians who have verified that your pet has received all required testing, vaccinations or treatments.
Do Indoor Pets Need to Be Vaccinated?
Yes. Even pets that live entirely indoors can still be exposed to dangerous diseases. Pathogens are resilient and can enter the home in numerous ways. People may carry viruses, bacteria or fungal spores on their clothing or shoes. . Wildlife or stray animals carrying diseases like rabies may also find their way indoors through open windows, doors or balconies. Routine veterinary visits, grooming appointments or boarding facilities can also bring animals into contact with one another, increasing the chance of exposure. Finally, if an indoor pet ever escapes, it may be completely unprotected against the diseases in their surroundings without vaccination.
Do Pets Like Rabbits, Birds and Hamsters Need Vaccines?
Unlike dogs and cats, most small mammals (such as hamsters and guinea pigs), rabbits and pet birds do not have routine vaccination schedules. Instead, their health is usually protected through good husbandry, including proper diet, clean housing and regular veterinary care. There are a few exceptions:
- Ferrets: in many countries, ferrets are typically vaccinated against .
- Rabbits: in and some other countries, vaccines are available against (RHDV) and .
- Birds:: a vaccine is available for parrots to help prevent infection (APV). Species particularly susceptible to APV include budgies, eclectus parrots, caiques and hawkhead parrots. Usually, the vaccine is recommended for birds that are , such as in pet stores or breeding environments.
If you own an exotic pet, it’s best to consult an avian or exotic veterinarian about vaccines.
Vaccines and Livestock
How Can Farmers Create Successful Vaccination Plans?
In most countries, livestock vaccination isn’t mandatory, leaving the decision up to farmers. Yet, uncertainty, fear of failure or the perception that vaccination is complicated can discourage action. —they can help farmers design tailored vaccination programs and avoid costly mistakes. include improper vaccine storage or handling, using expired products, , vaccinating animals that are sick or stressed, spreading contamination within the herd and neglecting booster schedules.
Training, education and professional guidance are critical to making vaccination both effective and manageable. Advances in vaccine delivery may also simplify the process. Most livestock vaccines are currently administered by injection, which is less user-friendly. New methods, such as tablets, or other needle-free systems, could reduce this burden. Developing that eliminate the need for cold storage could also significantly improve access in remote areas.
How Does Vaccinating Livestock Prevent Antimicrobial Resistance?
Better use of vaccination against bacterial pathogens, such as in cows, sheep, goats and pigs, or in poultry, can prevent disease in animals, reducing the need for antibiotic treatments. Many are similar or identical to those used in humans. Overuse and misuse of antibiotics in animals and humans can lead to antibiotic-resistant bacteria, which can then be transmitted to humans through food and other routes.
How Does Livestock Vaccination Support Economic and Food Security?
Vaccinating livestock is the best way to prevent disease outbreaks from spreading among animals in close quarters. Healthy herds also protect rural livelihoods and national economies. rely on livestock. Their income depends on the eggs, milk, meat and other animal products their livestock produce. of the world’s agricultural gross domestic product (GDP) is attributed to livestock, making animal health part of the foundation of economies worldwide. Maintaining good animal health is also important for the global food supply. On average, .
Vaccines and Wildlife
Why Vaccinate Wildlife?
Vaccinating wildlife reduces the spread of disease and the risk of outbreaks that affect communities and agriculture. In addition, it's crucial for protecting endangered species. In Australia, a new single-dose vaccine in September 2025 to protect endangered koalas from chlamydia, which is responsible for up to half of koala deaths in the wild. The vaccine, which will be given as a single dose and delivered by a needle, could reduce the likelihood of koalas developing symptoms of chlamydia during breeding age and . The first batch of vaccines will focus on vaccinating , with the hope of expanding efforts to wild populations.
Novel vaccines are also under development to protect endangered species, including against (DFTD), which is transmitted not by a microorganism, but rather the contagious cancer cells, which are spread between devils during biting. against white-nose syndrome and against avian cholera are also being developed.
How Are Wild Animals Vaccinated?
Catching wild animals for vaccination is difficult and impractical on a large scale, so most wildlife vaccines are delivered orally. The vaccine is and is released when the animal eats the bait, triggering an immune response. One of the most successful examples is the oral rabies vaccine. First tested in red foxes in Switzerland in the 1970s, it is now —often by airplane—to protect raccoon populations. Baits are flavored to attract specific species, such as a .
Listen as Rodney Rohde, Ph.D., Regents’ Professor and Chair of the Medical Laboratory Science Program at Texas State University, discusses his experience participating in the first U.S. program approved to drop rabies vaccines for coyotes and foxes, the primary vectors for canine rabies in Texas.
What Are the Challenges of Vaccinating Wildlife?
Vaccinating wildlife presents a unique set of challenges. Vaccines rarely provide perfect immunity, and most, aside from certain live vaccines (which aren’t safe or practical in all scenarios), require booster doses to ensure strong protection. Delivering a second dose to free-ranging animals is costly, labor-intensive and can cause unnecessary stress to populations. To address this, researchers are developing vaccines that . Vaccination strategies must also be tailored to the biology of each species and the characteristics of the disease. For example, oral baiting has proven effective in some species, but its success depends on . To improve outcomes, scientists use different to inform when and where vaccines should be deployed and which hosts should be prioritized for vaccination.
The Takeaway
Vaccination is a key part of animal health, helping pets, livestock and wildlife live longer, healthier lives. By preventing disease, vaccines reduce animal suffering and help limit the spread of zoonotic pathogens. Despite advances in veterinary vaccines, challenges remain in ensuring all animals are protected. These include limited access or resources in rural or underserved areas, financial barriers, gaps in awareness or education, logistical difficulties in vaccinating wild populations and skepticism around vaccines. Overcoming these obstacles will require coordination from government, industry, research and education. If you have questions about animal vaccines, your veterinarian is the best resource for guidance.
Not all microbes make animals sick. What can we learn about animals by studying their microbiomes? And how can those insights be used in wildlife conservation?
Author: Ava Walderman
