Curiosity Won't Kill Your Cat, but Avian Influenza Might

Highly Pathogenic Avian Influenza (HPAI) in Cats

Since the start of 2022, the United States has been plagued by a severe outbreak of highly pathogenic avian influenza (HPAI), also referred to as "bird flu." HPAI is an influenza A virus that can be carried by wild birds to domestic poultry, causing significant mortality. Most cases during this outbreak have been confirmed to be the H5N1 subtype. Over 150 million poultry have died because of HPAI since the beginning of the outbreak, which has had a devastating effect on the price and availability of eggs and other poultry products for consumers. This virus has also infected mammalian species, including wildlife, humans, and domestic animals. Recently, there has been growing concern about the ability of H5N1 to cause severe illness in cats, as well as the possible risk of disease transmission between cats and humans.

How Has This Outbreak of Avian Influenza Evolved?

While HPAI has been reported sporadically in wild and domestic cats since the start of 2022, reports of outbreaks in feline species are becoming more common. In the summer of 2023, two feline outbreaks of H5N1 HPAI were reported in other countries: one in Poland affecting over 30 household cats and one in Korea linked to contaminated food that affected 38 cats in animal shelters. The same year in the United States, there were 14 cases of HPAI in domestic cats and 25 cases in larger members of the Felidae family, primarily mountain lions and bobcats. In March of 2024, dairy cattle began testing positive for H5N1 HPAI. Preliminary studies suggest dairy cattle were initially exposed to HPAI from infected wild birds, and the disease was then rapidly spread between cattle across the country during routine movement and trade. This new outbreak has highlighted the ability of the virus to evolve in a way that allows it to cause disease in mammalian species more easily. In 2024, domestic cat cases increased over four-fold to 59 cases, while cases in larger Felidae increased slightly to 33 cases.

How Are Cats Becoming Infected With Avian Influenza?

There are several ways that cats are suspected of becoming infected with avian influenza.

Ingestion of Raw/Unpasteurized Milk and Raw or Undercooked Meat

This is the most common route of exposure in feline cases of HPAI.

There have been several reports of sick or dead barn cats found on dairy and poultry farms during avian influenza outbreaks. These cats may have hunted and ingested infected wild birds or scavenged carcasses from birds that had died from the disease in the surrounding area. In some cases, farm cats may have consumed virus-contaminated raw milk after it was offered to them by farm personnel or spilled during daily operations.

Big cat species in the wild and in captivity have become similarly infected by eating raw meat and carcasses from infected birds.

Domestic cats that do not have outdoor access have still become infected by consuming raw commercial pet food, unpasteurized (raw) dairy products, and raw or undercooked meat purchased by their owners.  

Exposure to Infected Wild Birds or Poultry

Birds shed avian influenza through their bodily fluids and feces, and the virus can survive for a very long time when protected in organic material and water. Even if cats do not ingest meat from infected birds, they can still become infected if they are in close contact with a bird that is shedding the virus. Cats may drink from puddles or ponds shared with infected birds. They may also walk through feces or dirt harboring the virus, then ingest it while grooming.

Exposure to the Virus on Clothing or Equipment from Farms With Infected Animals

If members of a household work on a dairy or poultry farm, they may track infectious milk, feces, or bodily fluids home with them on their shoes, clothing, or tools.

Exposure to Infected People

Transmission between cats and humans is possible, but it has only been suspected in two cases during this outbreak. Further investigation is required to understand these transmission dynamics and determine the true risk.

What Does Infection Look Like in Cats?

Early in the course of infection, cats may start displaying nonspecific symptoms of illness, including decreased appetite, fever, and lethargy (decreased energy). As the infection progresses, symptoms will rapidly worsen and may include the following:

• Neurologic signs: ataxia (lack of coordination and balance), circling, tremors (shaking), seizures, blindness
• Depression: severe weakness, unresponsiveness
• Respiratory signs: discharge from the eyes and nose, rapid breathing, difficulty breathing, sneezing, coughing

Most reported cases of H5N1 HPAI in cats have resulted in death shortly after the onset of symptoms.

What Should I Do if I Suspect a Cat is Infected With Avian Influenza?

Step 1: Take precautions to protect the members of your household

While the risk of avian influenza transmission between cats and humans is currently low, it is still theoretically possible. The American Veterinary Medical Association (AVMA) and US Centers for Disease Control and Prevention (CDC) have issued recommendations for handling cats that may be infected with avian influenza, including isolating the sick cat in an area away from other members of the household and hand washing with soap and water after interacting with the cat. The use of personal protective equipment (PPE), such as gloves and masks, can be used to further reduce risk.

Step 2: Call your veterinary clinic to describe symptoms prior to bringing cats in

Some of the neurological signs seen in cats with avian influenza can also be seen with rabies infection, so the veterinary team will need to take precautions to prepare for your visit. Maintaining up-to-date rabies vaccination schedules and detailed records for all household pets will minimize this concern.

Step 3: Monitor other household members for signs of illness.

Even if it is unlikely for other household members to become infected directly by sick cats, they may have been exposed to the same infected material that caused illness in the cat. If other members of the household become sick, they should contact their doctor for further instructions.  

How Can I Protect My Cats from Becoming Infected With Avian Influenza?

There are no vaccines available for cats that protect against HPAI infection, nor are there any specific treatment options for cats that do become infected. Right now, preventing disease through lifestyle changes is the best form of protection. Cat owners and caretakers can refer to this list to reduce the risk of avian influenza infections in cats:

Keep cats indoors

• Prevent cats from coming into contact with birds and other wildlife.
• If you live on or near a farm, prevent cats from gaining access to livestock and poultry operations.
• Monitor your area for known H5N1 outbreaks using case mapping provided by the United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS), U.S. Geological Survey, and the Pennsylvania Department of Agriculture (PDA).  Restrict outdoor access for cats, especially in high-risk areas.

Avoid feeding cats raw, unpasteurized, or undercooked animal products

• Refrain from feeding cats unpasteurized (raw) dairy products or colostrum
• Follow the United States Department of Agriculture Food Safety and Inspection Service’s (USDA-FSIS) Safe Minimum Internal Temperature Chart (table shown below) to thoroughly cook meat before feeding it to your cats.
• Refrain from feeding pet food diets and treats that are advertised as raw.

Minimize the risk of household members bringing in infectious material.

• Limit your own contact with wildlife, including sick or dead birds
• Wash your hands with soap and water before and after handling your cat or encountering poultry, livestock, and wildlife.
• If contact with poultry, livestock, and wildlife cannot be avoided, change your clothes and shoes, and thoroughly wash any exposed skin before handling your cat
• If you travel past bird feeders, poultry farms and backyard flocks, or places where wild birds gather, change your shoes or disinfect their soles before entering your house.

Contact your veterinarian

• Immediately contact your veterinarian if you notice signs of H5N1 or think your cat might have been exposed to the virus.

How Can I Protect the Rest of My Household or Farm from Avian Influenza?

There are numerous resources available to assist farmers and households in learning more about HPAI, staying updated about the ongoing outbreak, and improving biosecurity and protection on their property. We have included links to some resources below:

• World Organization for Animal Health Avian Influenza Landing Page
• USDA Avian Influenza Landing Page
• USDA Defend the Flock
• Pennsylvania Department of Agriculture Avian Influenza Landing Page
• Penn State Extension Avian Influenza Landing Page
• Poultry Biosecurity

Who Should I Contact if I Have Sick Birds or Suspect HPAI in My Flock?

Pennsylvania residents should contact the Pennsylvania Department of Agriculture via the hotline 717-772-2852 and select option 1 to reach the on-call veterinarian. Poultry owners in other states should contact their State Veterinarian or the United States Department of Agriculture (USDA) Healthy Birds Hotline at 866-536-7593.

Authors: Emily Frye, DVM, MBA; Kayla Niel, DVM, MS, DACPV; Megan Lighty, DVM, PhD, DACPV