Influenza (Flu)

Influenza in Animals

For information about the current H5N1 avian influenza (bird flu) outbreak, please see the CDPH Bird Flu webpage.
For information about seasonal flu in humans, please visit the CDPH Influenza (Flu) webpage.

What You Need to Know

Pets (dog, cats), poultry (chickens, turkeys), and livestock (cattle, pigs, horses) can all get their own kinds of flu.
Flu viruses from some animals (birds, pigs) can make people and other animals (cattle, cats, wildlife) sick. But flu viruses from pets and other companion animals (dogs, horses) are not generally a health concern for people or other animals.
People can help prevent the spread of flu by washing their hands often with soap and water, getting vaccinated, and avoiding close contact with sick animals and people.

Influenza (flu) is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs in both people and animals. Many animals have their own flu viruses that can cause them to have fever, tiredness, and respiratory symptoms such as cough, runny nose, and trouble breathing. Some animals infected with flu viruses can look healthy, but they are still able to spread the virus to other animals. Bird or swine flu can spread very fast between animals and cause large numbers of animals to get sick and die.

Chicken

Specific Kinds of Flu in Animals

(click to jump to section)

Flu Type	Types of Animals Infected	Makes People Sick?
Swine influenza	Pigs	Yes, sometimes
Avian influenza	Poultry, wild birds, mammals	Yes, sometimes
Canine influenza	Dogs, cats	No
Equine influenza	Horses	No

Swine/Variant Influenza (Swine Flu)

Swine influenza—or swine flu—is a respiratory disease in pigs that is caused by influenza (type A) viruses. Swine flu is common in pigs but does not usually spread to people or make them sick. When a person gets sick from a swine flu virus, it's called “variant flu." Some outbreaks of variant flu have happened in the past from pig shows at fairs and other public events. People who work with pigs or have frequent contact with pigs are at higher risk of getting variant flu.
Sometimes swine flu spreads to people. The 2009-2010 H1N1 flu pandemic was caused by a new type of variant flu and contributed to an estimated 60.8 million people infected in the U.S. in 12 months.
Flu vaccines for pigs are available, but the right kind of vaccine needs to be carefully selected and used. Pig owners should talk with their veterinarian about which flu vaccines are best for their pigs.

Pigs

Learn More

Avian Influenza (Bird Flu)

Avian influenza—or bird flu—is caused by influenza (type A) viruses that commonly infect wild birds. Bird flu can infect poultry (chicken, turkeys), wild birds (ducks, geese), and other animals. It can cause different kinds of disease in animals, not just respiratory illness.
Bird flu rarely infects people. Certain types of bird flu spread quickly among birds and kill many birds in a short time. These flu types are known as highly pathogenic avian influenza (HPAI). HPAI is particularly devastating when it infects poultry raised for human food, as hundreds or thousands of birds in commercial flocks can die in just a few days.

When many wild or domestic birds are sick with bird flu, there is a greater chance for people to have contact with sick birds and be exposed to bird flu viruses. Because of this, the concern of bird flu spreading to people is greater when bird flu is causing many illnesses and deaths in bird populations.
Do not touch sick or dead wild birds. If you have questions about a dead bird you found, or wish to report it, please see Reporting and Testing of Sick and Dead Birds by California State Agencies (PDF).

Chickens, turkeys, ducks, and other birds raised for meat or eggs should be kept away from wild birds. Flu vaccines for birds are not widely available. Discuss with your veterinarian how to practice good biosecurity to protect your poultry from getting flu.

Wild birds, especially waterfowl (ducks, geese), are natural carriers of bird flu viruses. When these birds migrate and stop along the way in California, they can infect other birds and spread bird flu in the area. This may be one reason that bird flu activity in California increases in the fall when birds fly south for the winter.

Learn More

CDFA Avian Influenza Updates
Detections of Highly Pathogenic Avian Influenza – U.S. Department of Agriculture (USDA)
CDC Avian Influenza (Bird Flu)

Canine Influenza (Dog Flu)

Canine influenza—or dog flu—is a contagious respiratory disease in dogs caused by influenza (type A) viruses. There are no documented cases of dog flu in humans, and current dog flu viruses are not a health concern for people.
Dogs with flu can have cough, runny nose, fever, tiredness, eye discharge, and reduced appetite. Not all dogs will appear sick, but some dogs can have more severe disease and die from dog flu.
Vaccines for dog flu are available from your veterinarian. There is no specific medication to treat flu in dogs, but a veterinarian can provide care that will help them feel better sooner.
Cats can be infected with flu viruses from dogs or birds, but this is rare. To protect your cat from bird flu:

Do not allow your cat to hunt or kill wild birds.
Do not feed your cat raw foods, including raw (unpasteurized) milk. Cats have gotten sick and died from bird flu after eating raw pet food or drinking raw milk.

Learn more: Cat deaths linked to bird flu-contaminated raw pet food, sparking voluntary recall (AVMA, January 2025)

Keep your cat away from dogs that have (or could have) flu.

“Cat flu" is a general name for different respiratory diseases in cats. “Cat flu" is not actually caused by influenza viruses, and it does not spread to people or other animals.
Dogs and cats rarely become infected with human flu viruses and generally do not pass on the infection to people or other animals. To protect pets from getting sick, people sick with flu should limit their contact and time spent with pet dogs and cats until they are no longer sick.

Learn More

CDC About Dog Flu
Canine Influenza – American Veterinary Medical Association (AVMA)

Equine Influenza (Horse Flu)

Equine influenza—or horse flu—is a respiratory disease in horses caused by influenza (type A) viruses that are different from flu viruses in other animals. Horse flu is very contagious among horses and can easily spread from a sick horse to other horses nearby, or when horses have contact with materials and objects that had contact with sick horses.
Horse flu is not known to infect people, but people can spread horse flu between horses.

People who care for a horse with horse flu should wear protective clothing such as latex gloves and boots that can be washed and disinfected. After caring for a horse with flu, people should change clothes and wash their hands before working with other horses. Equipment, tack, and other materials used to care for a sick horse or clean areas where the horse is kept should be thrown away or disinfected before being used again.

There is a vaccine for horse flu. Talk to your veterinarian about which vaccines your horse(s) needs, especially those that are pregnant or very young.

Learn More

CDC About Horse Flu

Can people get flu from animals?

Yes. Some animal flu viruses, especially those in pigs and birds, can infect people and make them sick. But companion animals (such as dogs and horses) that have flu are not a risk to their owners and other people.

Flu viruses in animals occasionally become able to infect people and make them sick. People can be exposed to animal flu viruses when they have close contact with infected animals or their environments. Most people have little immunity to animal flu viruses because they have not been exposed to them before. Most animal flu viruses that can infect humans do not spread easily between people.

How does flu spread from animals to people?

Flu viruses usually spread through droplets that come from an infected animal's nose and mouth. Droplets spread through the air when an animal coughs or sneezes. People can get infected when they breathe in these virus particles from droplets in the air or if they touch a surface where the droplets have landed and then touch their eyes, nose, or mouth. Birds shed flu virus in their feces (poop), and people can become infected with bird flu through contact with poop particles on surfaces or in the air.

People can also spread flu to animals.

When a person is infected with flu, droplets from their nose and mouth can spread flu virus into the air (such as when coughing, sneezing, or talking). Animals can also breathe in these viruses and get sick. Certain kinds of animals that can get flu from people include cats, pigs, and ferrets.

Prevention

What everyone needs to know

If you visit animals at fairs, petting zoos, educational farms, summer camps, or other places where animals are present, you can help prevent the spread of flu viruses by following these steps:

Wash your hands often with soap and water.

Regular handwashing can remove harmful germs and prevent illness.
Handwashing is very important after touching or being around animals and before eating or putting anything in your mouth.

Stay away from sick or dead wild animals, especially wild pigs (boar) and wild birds like ducks and geese.
Pigs and birds that seem healthy can still spread germs. Young children and older adults are more likely to get sick from animal germs, even if they are healthy. People in these groups should stay away from pigs and birds (such as chickens and ducks) and should not visit swine or bird barns and exhibits.
Keep food and drink for humans out of barns, coops, and other areas where animals are kept — don't eat, drink, or put anything in your mouth while you are in animal areas and not until after you wash your hands after leaving animal areas.
Don't take toys, cups, or other household items into animal areas where they can get contaminated with animal germs.

Prevention tips for people who own or show poultry and pigs

People who raise and show birds and pigs can follow these additional steps to help prevent flu in their animals:

When you add a new animal to your herd or flock, keep it separated until a veterinarian can examine it and check that it is not carrying any diseases.
If you or someone close to you is sick with flu-like symptoms (such as cough, fever, or runny nose), plan for someone else to feed and care for your animals until you and your close contacts are well.
Keep animal areas clean by regularly removing poop and washing surfaces with soap and water. When removing pig poop and bird droppings from a pen or cage, wear protective clothing, gloves, and a mask that covers your mouth and nose.
Make sure that animals receive regular veterinary care, including preventive care such as vaccinations.