Avian Influenza: Information for Animal Health Care Providers

Wild water birds, such as ducks, geese, swans, gulls, terns, and shorebirds, are considered the natural hosts for bird flu viruses including the H5N1 bird flu virus that has been found in the US since 2022. Increased detections of avian influenza in NYC likely correspond to the colder temperatures of winter and peak migration season for water birds.

Infected birds shed the virus in their feces and respiratory secretions. Bird flu viruses spread most readily to other water birds but can spillover to other species and infect poultry birds, raptor birds, and numerous types of mammals. Usually, mammals are considered dead end hosts and they rarely infect other animals. However, spillover into dairy cattle has been an exception and there has been extensive cow to cow transmission primarily through contaminated milking equipment.

Most pets are unlikely to be at high risk of exposure to H5N1 while outdoors in NYC. Owners can reduce the risk to their pet by not feeding them raw dairy, raw meat, raw poultry, or raw pet food diets, and not letting them roam freely outdoors to avoid contact with infected birds.

We are still learning about this virus in cats. Most cats with H5N1 in the United States consumed infectious raw milk, raw poultry, or raw pet foods, or had exposure to infected wild birds or other cats. Cats often had severe illness, including neurologic disease. However, we are still learning about the full spectrum of illness, which may include subclinical infection. Approximately 1,000 cats in New York State with neurologic disease that were submitted for rabies testing and were rabies negative were all tested for H5. All of the cats tested negative. Studies are underway to screen stray cats in NYC for H5 and learn whether outdoor cats may be at risk.

Dogs appear to be less susceptible to H5N1 than cats. One fatal infection was reported in Canada in a dog that had been chewing on an infected bird. Researchers in the Pacific Northwest detected antibodies to H5 and N1 in a small number of hunting dogs, suggesting transmission of H5N1 from waterfowl to dogs can occur. However, the small number of detections and the lack of reported disease suggests the virus is poorly adapted to dogs.

Strongly advise pet owners not to consume or feed their pets raw dairy, raw meat, raw poultry, or raw pet food diets. Share information about the risks to both human and pet health when feeding raw diets.

Advise cat owners to keep cats indoors to prevent exposure to wild birds and other animals.

Stay aware of recalls and share them with pet owners. Both pet products and human grade products that are fed to pets may be recalled:

• FDA Recalls, Market Withdrawals and Safety Alerts

Share the following with staff:

• Wild water birds are the reservoir for H5N1. It has been detected in wild birds, poultry, and house cats in NYC.
• Sick animals can shed H5N1 avian influenza virus in their saliva, urine, feces, and other body fluids. Human infections can occur when droplets containing the virus are inhaled or enter a person's eyes, nose, or mouth.
• While cat to cat transmission has occurred, there are no reports of cat to human transmission.
• Perform good hand hygiene before and after patient care, being in the patient environment, and after removal of PPE.

More studies are needed to get the full clinical picture of H5N1 disease. From reports of recently infected cats, illness may follow this progression:

• Start with loss of appetite, lethargy, and fever.
• Quickly progress to neurologic signs (ataxia or incoordination, circling, tremors, seizures, or blindness), severe depression, respiratory signs, including rapid or difficulty breathing, and possibly sneezing or coughing, and ultimately death.
• Note that a small number of cats have had mild illness, including fever, and recovered.

Consider screening questions for any cat or other animal with acute onset of respiratory or neurologic disease of unknown cause to identify known risk factors for exposure to H5N1. Ask:

• Has your pet recently consumed fresh, frozen, or freeze-dried raw pet food or raw poultry?
• Has your pet recently consumed raw unpasteurized milk?
• Has your pet recently been exposed to sick or dead wild birds or other wildlife?
• Does anyone in the household work in a live bird market?
• Has anyone living in the household recently been exposed to or visited a farm with known or suspected H5N1 infections?
• If the owner answers yes to any of these questions, consider including influenza H5N1 on your differential list and taking infection prevention precautions to reduce risk of spread to staff and other patients.

Isolate patients.

• Have animals wait outside and then, if possible, bring them in through an alternate entrance. Do not allow these animals to wait in a lobby area or mingle with other healthy patients.
• Isolate cats or other animals presenting with acute illness and compatible risk history. Isolation should ideally take place in a separate room away from other animals, including other species.
• Use patient dedicated equipment, and clean and disinfect all items removed from the isolation area. Bring into isolation only the items that you need. Any single-use items that cannot be cleaned and disinfected properly need to be thrown away after patient discharge.

Minimize exposure to staff and other animals.

• Keep the number of people who handle the animal to a minimum.
• Staff handling the animal should use recommended PPE.
• PPE should include an N95 mask, gloves, goggles or a face shield, gown, gloves, hair cover, and shoe covers.
• If an N95 is not available, a well-fitted face mask covering the nose and mouth should be used.
• Eyeglasses alone should not be used for eye protection.

Follow hand hygiene and standard precautions.

• Perform hand hygiene by washing hands with soap and water or using alcohol-based hand sanitizer.
• Perform hand hygiene before and after patient care, after being in the patient environment, and after removing PPE.
• All veterinary staff (including kennel staff and cleaners) should change shoes and clothes before leaving the clinic.
• No eating or drinking should be allowed in areas used for patient care.

Clean and disinfect.

• Thoroughly clean and disinfect all areas, surfaces, and equipment that the patient may have come in contact with.
• Read the disinfectant label to ensure that the disinfectant being used is appropriate to kill influenza virus, an enveloped virus.
• The disinfectant must remain wet on the surface for the entire contact time as directed on the label before wiping off.

At this time, veterinarians are asked to contact the NYC Health Department about any cat or other mammal suspected of H5N1 infection that meets the following criteria for consultation and to arrange for testing:

1. A clear epidemiologic link, such as consumption of raw milk, raw pet food, or raw poultry or meat, or recent contact with sick or deceased wild birds, backyard poultry flocks, or poultry in live bird markets; and
2. Acute onset of compatible clinical signs, which may include:
• Fever (for at least one cat fever was the only sign)
• Severe lethargy
• Loss of appetite
• Acute respiratory disease
• Acute neurologic disease
• Hepatopathy or icterus
• Uveitis

The NYC Health Department will coordinate submissions to Cornell University. Multiple specimens are accepted for H5 testing in cats. The best samples from live cats are not yet known and Cornell is recommending all four of the following samples at this time. These are:

1. Oropharyngeal (preferred) or nasal swab from both nares in a plain sterile container such as a red top tube or viral transport media
2. EDTA whole blood in a purple top tube
3. Urine in a sterile container
4. Fecal swab in plain container

For deceased cats, Cornell is requesting submission of the entire carcass. If rabies is on the differential, this will also facilitate rabies testing first, followed by H5 testing at Cornell.

Commercially Available Influenza Assays

It is not clear if commercially available influenza assays can reliably detect H5 in cats and other mammals. The NYC Health Department encourages any testing be done through Cornell University for highly suspicious animals to avoid delays in getting confirmatory results and guiding appropriate follow up. At this time, coordinating through the NYC Health Department will help avoid testing fees for animals meeting testing criteria.

The NYC Health Department is notified of any laboratory detection of avian influenza. Investigations are done in response to initial reports of suspected H5 infected animals, as well as laboratory reports of confirmed H5 infected animals. Health Department staff will follow up with the clinic, staff, and the pet owner to conduct arrange symptom monitoring, testing and prophylaxis, if indicated. We will also conduct a short interview to gather information about the ill patient and be available to answer any questions.