H1N1 Flu Virus: For Veterinarians (FAQ)

Updated February 14, 2011

These questions and answers are based on what is currently known about the virus, and will be updated as we get new information.

Q: What are the clinical signs of 2009 H1N1 flu virus infection in pets?

A: So far, the clinical signs observed in pets have been respiratory problems, such as coughing, sneezing, ocular and/or nasal discharge (may be clear), and possibly fever, lethargy, loss of appetite, and respiratory abnormalities (e.g., dyspnea, tachypnea). In other words, it resembles most other viral respiratory infections. To date, five of the eleven infected cats died from severe pneumonia.

If there is a history of recent flu-like illness among the pets' owners and the pet begins showing signs of respiratory disease, a high index of suspicion of 2009 H1N1 influenza exists.

An infected cat in southern California showed clinical signs (nasal discharge, sneezing and occasional cough) according to the owner, but was clinically normal when examined by a veterinarian the following day. This emphasizes that there may be pets that are subclinically infected and recover without any problems.

Keep in mind that dogs currently have their own flu virus, the H3N8 influenza (canine influenza) virus, going around. So far, this flu virus has only been spread from dog to dog. Dogs infected with the canine influenza virus show the same clinical signs as dogs with kennel cough – fever, lethargy, loss of appetite, coughing, and maybe a runny nose. For more in-depth information on canine influenza, view our canine influenza backgrounder.

Q: If the cat has Felv or FIV, or if the pet has cancer is it more susceptible to the 2009 H1N1 virus?

A: Theoretically, yes…but we really don't know. We already know that immunocompromised animals are at higher risk of disease and complications. We do know that immunocompromised people, pregnant women and people with existing medical conditions are at higher risk of illness and death due to the 2009 H1N1 flu virus, and the same may apply to animals. We just don't have enough information at this time to know for sure. To date, most of the infected pets were older animals, but we don't have enough information to determine the significance of this finding.

One of the cats that died was reported to have had a history of chronic upper respiratory disease. This may have contributed to the severity of the cat's illness and its death, and underscores the importance of protecting at-risk cats from infection.

An 8-year old cat was confirmed to be infected with Mycoplasma felis as well as the 2009 H1N1 influenza virus and another 8-year old cat was coinfected with feline herpesvirus. It is unknown if the Mycoplasma infection was preexisting but if it was, it is possible that the Mycoplasma infection increased the cat's susceptibility to the influenza virus. The cats are recovering from their illness.

Q: A client suspects their pet is infected with the 2009 H1N1 virus and wants to bring it in for examination and testing. What should we recommend?

A: Because infection with the 2009 H1N1 virus may resemble other viral respiratory diseases that cause illness and can be life-threatening, it is important to thoroughly evaluate any animal presented with respiratory infection. Until we know more about the potential for infected pets to spread the virus, they should be managed as potentially infectious patients. Proper quarantine, hygiene and sanitation measures are important.

Q: What quarantine measures should we take when handling an animal suspected to be infected with H1N1?

A: Right now, we don't know the likelihood that an infected pet will spread the 2009 H1N1 virus to other pets or to people. Therefore, we recommend managing pets that are suspected or confirmed to be infected with the virus in the same manner as a pet with a viral respiratory infection: proper quarantine, hygiene and sanitation measures are important. Veterinarians can refer to the Compendium of Veterinary Standard Precautions for Zoonotic Disease Prevention in Veterinary Personnel for guidance.

Although we don't know the risks of transmission of the 2009 H1N1 influenza virus from pets to people, we can't say it's not possible. Veterinarians and veterinary staff treating and handling pets with respiratory disease and a history of flu-like illness in the pet's home should consider the use of facial protection covering their mouth, nose and eyes.

Q: What are the chances an infected pet will infect other animals, or even the veterinary staff, while at my clinic?

A: We don't really know. To date, evidence has supported that the pets that have been infected with the 2009 H1N1 flu virus were infected by their owners. There is no evidence that the pets spread the virus to any other animals or to people. However, because we don't fully know the risk, animals suspected or confirmed to be infected should be managed in the same manner as a pet with a viral respiratory infection. Veterinarians and veterinary staff treating and handling pets with respiratory disease and a history of flu-like illness in the pet's home should consider the use of facial protection covering their mouth, nose and eyes. Veterinarians can refer to the Compendium of Veterinary Standard Precautions for Zoonotic Disease Prevention in Veterinary Personnel for additional guidance.

Q: I'm worried that a staff member might spread H1N1 to our hospitalized animal patients, especially because many of them are already ill or stressed. What do we do?

A: First and foremost, staff members who are ill should use common sense and stay home. This protects other staff members as well as the patients in your clinic. Having a good pandemic plan and communicating the plan to your staff is critical. View the AVMA's guidelines on pandemic planning for veterinarians.

Q: Which tests are used to confirm 2009 H1N1 flu virus infection in pets?

A: Polymerase chain reaction (PCR) testing is the standard confirmatory test for the virus. Animals must be shedding the virus in order for it to be detected by the PCR assay; therefore, sample collection during the early phase of illness is optimal. Hemagglutination inhibition (HI) assays (specific for 2009 H1N1 virus) performed on convalescent serum can also be confirmatory in the absence of a negative PCR result.

"Bedside tests" or human-focused rapid tests (such as Directigen™ Flu A+B or QuickVue® Influenza tests) have anecdotally been used for presumptive detection of influenza type A virus infection in pets but are not specific for the 'classic' H1N1 influenza virus or the 2009 H1N1 influenza virus. The tests are commonly performed on nasal or oropharyngeal swab samples. However, these tests are not USDA-approved for this use and confirmatory tests are necessary before the diagnosis can be confirmed. In addition, increased demand by physicians for these test kits during flu season may affect the kits' availability. When coupled with a history of flu-like illness in the pet's owners, a positive result on these tests raises the index of suspicion for 2009 H1N1 virus infection.

Keep in mind that performing bedside influenza tests on pets may delay or even interfere with obtaining a definitive diagnosis because it may delay sending a sample to an approved NAHLN (National Animal Health Laboratory Network) laboratory. In addition, these tests have not been validated or approved for detection of the 2009 H1N1 virus. If these tests are used, it is still critical that veterinarians submit samples (regardless of a positive or negative result on the test) from suspected cases of 2009 H1N1 influenza infection to an approved NAHLN laboratory for testing. This serves an additional purpose of providing tracking data for the USDA and CDC's surveillance systems. If 2009 H1N1 is suspected based on the pet's history and clinical signs, and a bedside test detects the presence of type A influenza, samples should be obtained for confirmatory testing.

On December 8, 2009, IDEXX Laboratories announced the availability of the IDEXX H1N1 Influenza Virus RealPCRT Test, offered as a stand-alone test or as a component of their canine and feline respiratory disease panels. This test has not been validated by the USDA but was adapted from published CDC standards regarding tests for the 2009 H1N1 influenza virus. Veterinarians who have received preliminary or confirmatory positive results of 2009 H1N1 infection in animals should alert their state public health veterinarian. Confirmatory testing by an NAHLN laboratory may be recommended.

Q: What samples should be obtained if I suspect a pet is infected with the 2009 H1N1 influenza virus?

A: Based on current knowledge, we recommend collecting an oropharyngeal, tracheal or nasal swab. Serum should also be collected. The samples should be collected on a dried polyester fiber swab (e.g., Dacron™) or flocked swab (e.g., Copan) and placed in a sterile tube with a few drops of viral transporting medium or saline. Do not use bacterial transport medium. The first cat (Iowa) confirmed to be 2009 H1N1 influenza-positive was diagnosed based on testing of a sample obtained by bronchoalveolar lavage (BAL) during anesthesia, indicating that BAL samples are also sufficient for testing.

Q: How can I test a pet I suspect is infected with the 2009 H1N1 flu virus?

A: Early in the course of illness, an oropharyngeal or nasal swab may be sufficient for testing. However, the animal must be shedding the virus in order for the PCR test to identify the presence of the virus. At this time, we do not know how long pets will shed the virus in their respiratory secretions. In the case of the 2009 H1N1-positive cat in Utah, PCR testing of a nasal swab obtained approximately one week after the onset of illness was negative for the virus, but a hemaglutination inhibition (HI) assay on a convalescent serum sample was positive for the virus at a 1:160 titer; this case suggests that pets may not be likely to shed the virus for more than a few days.

Samples for confirmatory testing should be sent to an AAVLD-accredited veterinary laboratory. Contacting an approved NAHLN (National Animal Health Laboratory Network) laboratory is highly recommended. A list of the swine influenza virus (SIV) approved NAHLN laboratories can be found at http://www.aphis.usda.gov/animal_health/nahln/downloads/siv_lab_list.pdf. The SIV approved NAHLN laboratories must request approval to the USDA for the rRT-PCR 2009 H1N1 assays to be used in species other than swine. SIV NAHLN laboratories with appropriate approvals can test nasal and/or pharyngeal swabs for the 2009 H1N1 flu virus (this is not a difficult procedure, and should not delay testing). The samples should be collected on a dried polyester fiber swab (e.g., Dacron™) or flocked swab (e.g., Copan) and placed in a sterile tube with a few drops of viral transporting medium or saline. Do not use bacterial transport medium.

Q: What happens if the test comes back positive?

A: If the veterinary laboratory's test is positive for the 2009 H1N1 virus, the sample is sent to the National Veterinary Services Laboratories (NVSL) for confirmatory testing. If the NVSL's testing confirms the infection, you will be notified.

Q: Can veterinarians from other countries submit samples to U.S. laboratories for testing?

A: Only if the U.S. laboratory has the proper permits for testing international samples. For veterinarians outside the U.S., the OIE/FAO Network of Expertise on Animal Influenza's Offlu site has a list of international veterinary diagnostic laboratories for submission of suspected Pandemic 2009 H1N1 2009 swine samples or isolates. If your country of practice is not listed, contact your country's ministry of health to request guidance.

Q: Is there a vaccine that can be used for pets? Can the human H1N1 vaccine be used for pets?

A: There is not a licensed and approved 2009 H1N1 vaccine for pets. The human H1N1 and swine H1N1 vaccines should not be used for pets.

Q: What are the current treatment recommendations for pets suspected or confirmed to be infected with the 2009 H1N1 flu virus?

A: At this time, we recommend you treat these cases the same way you would treat pets with any other viral respiratory infection: with monitoring and supportive care. As with any viral infection, secondary bacterial infections may occur and may require antibiotic therapy.

The decision regarding the use of antivirals, such as oseltamivir (Tamiflu), should be based on the severity of the animal's illness and your best clinical judgment. Please keep in mind that these products are not FDA-approved for use in pets and there is limited research or clinical information regarding the efficacy, safety and dosing of these products for pets. Inadequate dosing of antivirals could increase the risk of treatment failure, adverse events and/or antiviral resistance. The necessity of antiviral treatment should be weighed against these risks.

Q: Should infected pets be treated with antivirals?

A: Most people infected with the 2009 H1N1 flu virus have recovered with only supportive care and have not needed antiviral treatment. At this time, we have no reason to believe the situation is any different for pets.

The decision regarding the use of antivirals, such as oseltamivir (Tamiflu), should be based on the severity of the animal's illness and your best clinical judgment. Please keep in mind that these products are not FDA-approved for use in pets and there is limited research or clinical information regarding the efficacy, safety and dosing of these products for pets. Inadequate dosing of antivirals could increase the risk of treatment failure, adverse events and/or antiviral resistance. The necessity of antiviral treatment should be weighed against these risks.

Q: Could hospitalizing a cat with respiratory disease while waiting for H1N1 diagnosis be a liability for staff and other patients?

A: Simply put, we don't know if an H1N1-infected pet is capable of spreading the virus to other animals or to people. Our best advice at this time is to follow standard veterinary protocols for hospitalizing pets with respiratory disease, and use proper isolation/quarantine, hygiene and sanitation procedures.

Veterinarians can refer to the Compendium of Veterinary Standard Precautions for Zoonotic Disease Prevention in Veterinary Personnel for guidance.

Q: What if a pet needs an antiviral drug? Will veterinarians be able to get the antiviral drugs?

A: The 2009 H1N1 flu virus is spreading mainly by human-to-human contact. Keep in mind that pandemic planning, by necessity, must place a priority on treating infection in people-for that reason, antiviral medication supplies will be closely guarded and there may be strict guidelines in place that will determine how they are dispensed. Availability of antivirals may be low for non-pandemic response use. We encourage veterinarians to use their clinical judgment and weigh these factors when considering the necessity of an antiviral drug for a client's pet. The use of antiviral medications in food animals is strictly regulated—and is prohibited in some species—and food supply veterinarians are already aware of these regulations.

Q: Where can I go online to get updates on the situation?

A: We update our H1N1 resources page as soon as we receive and verify information, so it's a good source of information. In addition, the USDA has been listing the results of H1N1 testing on their H1N1 site.

Q: What should I tell worried clients?

A: The most important messages for clients at this time are not to panic and to have any ill pets examined by a veterinarian, especially if someone in the household has recently been ill with flu-like symptoms. To date, all of the infected pets were infected by ill people, and there is no evidence that ill pets have transmitted the virus to people or other animals. Emphasize the importance of proper hygiene and sanitation to prevent spread of the virus. Based on the currently available information, ferret and cat owners should be especially cautious.

Links to more information about the 2009 H1N1 flu

AVMA
Straight talk about the H1N1 virus
Dr. DeHaven, Chief Executive Officer of the AVMA, speaks with Bob Meyer of Brownfield (includes audio)

Dr. Ron DeHaven, chief executive officer of the American Veterinary Medical Association, explains H1N1 and how it affects people, their pets, and the food they eat.(May 1, 2009)

American Association of Swine Veterinarians (AASV)
AASV Human Cases of Swine Influenza

Flu.gov
Interactive timeline on H1N1: The Year in Review

CDC
CDC H1N1 Flu
For general information on H1N1 flu, general health information guidelines, updates on the status of the H1N1 flu outbreak, and travel advisories

2009 H1N1 Flu Frequently Asked Questions (including questions about H1N1 and domestic animals)

Interim Guidance for Workers who are Employed at Commercial Swine Farms: Preventing the Spread of Influenza A Viruses, Including the 2009 H1N1 Virus

USDA
USDA H1N1 flu information page

OIE (World Organisation for Animal Health)
A/H1N1 influenza like human illness in Mexico and the USA: OIE statement

OIE/FAO Network of Expertise on Animal Influenza (Offlu)

OIE/FAO Offlu list of international veterinary diagnostic laboratories for submission of suspected Pandemic H1N1 2009 swine samples or isolates

World Health Organization (WHO)
WHO Swine Influenza