The Health Implications Influenza Virus Infection Has For Pets

Patrick Mahaney, VMD, CVA, CVJ
By Patrick Mahaney, VMD, CVA, CVJ on Jan. 15, 2013

The influenza virus has come out in full force this year and sickened people from coast-to-coast. The 2012-2013 influenza is considered an epidemic, as infections have caused thousands to seek medical care and even caused a concerning number of deaths.

The CDC’s Situation Update: Summary of Weekly FluView reports:

The United States is having an early flu season with most of the country now experiencing high levels of influenza-like-illness (ILI) … since October 1, 2012, 3,710 laboratory-confirmed influenza-associated hospitalizations have been reported; an increase of 1,443 hospitalizations from the previous week.

With the seemingly increasing rate of influenza infections, recommendations to reduce new infections include practicing good sanitary habits and getting vaccinated.

The CDC’s Morbidity and Mortality Weekly Report indicates the influenza vaccination being currently administered to humans has an estimated vaccine effectiveness (VE) of 62%, which indicates "moderate effectiveness."

Considering that people can be infected regardless of vaccination status and that not everyone will be immunized, it’s important that we recognize the potential for humans to pass a microorganism like the influenza virus to our pets. Yes, your dog or cat could contract the flu from you.


The Spread of Zoonotic Diseases

Bacteria, viruses, fungi, parasites, or other agents (prions, such as those that cause Mad Cow Disease) all have zoonotic potential, meaning they are capable of spreading between humans and animals, or vice versa.

Although it is relatively uncommon for animals to contract viral or other infectious organisms from humans, it does happen. One notable occurrence was in 2009 when humans contracted H1N1 (swine flu) influenza virus from swine (pigs). Cats, dogs, and ferrets fell ill or died after contracting the H1N1 from people.

More information about cross-species illnesses can be found in my petMD article, Reduce the Potential for Zoonotic Disease Transmission


Clinical Signs of Influenza Infection in People and Pets

Cats, dogs, and people all show similar clinical signs of respiratory tract disease, including those that occur post-influenza infection:

  • Nasal or ocular discharge — clear, mucus, or even blood from the nose or eyes
  • Coughing — productive/moist or non-productive/dry cough
  • Increase respiratory effort (labored breathing) or rate
  • Lethargy
  • Digestive Tract Upset — vomit, diarrhea, and decreased appetite

If your cat or dog shows clinical signs of a respiratory tract illness (cough, sneeze, nasal discharge, lethargy, etc.), schedule an examination with your veterinarian


What About Dog or Cat Flu?

Canine Influenza Virus (CIV) and Canine Parainfluenza Virus (CPV) is contagious amongst dogs. The good news is that vaccines for both CIV and CPV are available

The typical companion canine does not receive a vaccine for CIV, in part because most dogs won’t be exposed to the virus.

Much more commonly, dogs are administered the vaccine for CPV, as it’s part of the DA2PP vaccination (also know as DHPP). In fact, DA2PP helps to protect against viruses that infect the canine respiratory tract (Distemper and Parainfluenza) and those affecting the liver and gastrointestinal tract (Adenovirus 2 and Parvovirius, respectively).

Conversely, there is no feline influenza virus, but the CDC reports that cats can serve as reservoirs for the H5N1 influenza and may show clinical signs of the disease. See Influenza Virus Type A Serosurvey in Cats.


Is the Canine Influenza Vaccine Appropriate for Your Pooch?

Juvenile, geriatric, and immunocompromised pets are more prone to contracting infectious diseases than healthy adults.

Environments that promote canine congregation are also hot zones for various diseases. These environments include:

  • Boarding facilities — kennels and daycare
  • Breed shows and interest group gatherings
  • Dog parks
  • Performance trials (agility, earth dog, etc.)
  • Shelters and rescues
  • Veterinary hospitals

These sites create the potential for direct interaction or exposure to the bodily secretions of other dogs (nasal, oral, etc.) and the exchange of disease causing agents. Additionally, the stress experienced during activity, travel, or confinement commonly alters normal patterns of eating, eliminating, and sleeping, thereby negatively impacting the immune system and making our canine companions more susceptible to infection.


Preventative Measures — Protecting Your Pet from the Flu

Besides immunizations, it’s important to provide our pets with the healthiest lifestyle possible to reduce their exposure to infectious organisms and ensure their immune systems can adequately fight off bacteria, viruses, and parasites.

This includes minimizing existing infectious disease in the body, such as the plethora of bacteria thriving in the canine mouth that readily enter into the bloodstream and damage the kidneys, liver, and other organs. Additionally, maintaining a healthy body condition puts less stress on all body systems and allows the blood and lymphatic vessels to more efficiently function to remove microorganisms.

Family members of all ages should practice good sanitary habits, including thorough hand washing with soap and warm water after touching an animal or other person. Additionally, close contact with pets and other people should be avoided during episodes of illness, both yours and theirs.


Have your pets ever suffered from a respiratory tract infection (or other disease) that was transmitted by another pet or person? Feel free to share your story.

And to see some great images of the influenza virus and how it works, visit the CDC's Seasonal Influenza page.

Dr. Patrick Mahaney

Image: Sick Chihuahua by Will Keightley / via Flickr

Patrick Mahaney, VMD, CVA, CVJ


Patrick Mahaney, VMD, CVA, CVJ


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