The first case of canine influenza virus (CIV) within the United States was reported on in 2004. Thought to be the result of a mutation that developed from a closely related equine influenza virus, CIV strain H3N8, was determined to be a factor in canine respiratory disease. In 2015, CIV was again confirmed following an outbreak in Chicago. However, these dogs were infected with a second and separate form of CIV, H3N2. Since its detection, canine influenza H3N2 has continued its spread across the United States.

The following provides helpful background information on the H3N2 virus for clinic staff.

Origination of Canine Influenza Virus

The H3N2 canine influenza occurring within the United States has a genetic makeup that is nearly identical to the H3N2 strain of CIV previously reported in Asia. Before being identified in 2015 within the United States, H3N2 had not been detected outside of Korea, China, or Thailand. H3N2 is believed to occur as the result of a direct transfer of an avian influenza virus to canines. Since the time of its identification within the United States, the diagnosis of H3N2 has been confirmed in thousands of dogs.

Spread of CIV

H3N2 is very contagious. Able to infect a dog of any age or breed, the virus occurs year-round and can be transmitted to uninfected animals through the following modes:

• Airborne. Virus is passed through the air when an infected dog sneezes or coughs
• Physical. Particles of virus can be passed when an infected dog touches an uninfected animal; for example, when they touch noses in greeting. Uninfected dogs that come into contact with items that have been touched by an infected dog, for example, a water or food bowl, bedding, or a chew toy, may become infected.
• Human. When touched, infected animals shed virus particles onto human hands and clothing. If the shed particles are not removed by disinfectant or washing, they can be passed on to an uninfected animal.

Transmission of H3N2

There is no evidence that either strain of CIV can be transmitted to people. However, the Asian H3N2 strain has been diagnosed in cats, and a shelter in Indiana was reported to have cats who became ill with the H3N2 virus after contact with infected dogs. It is believed that cat-to-cat transmission is possible with the H3N2 virus.

Clinical Signs of CIV Infection

Most dogs exposed to the virus are at risk of becoming infected. Since H3N2 is a relatively new disease, dogs on the whole have not yet had the chance to establish a build-up of natural immunity. Typically, the signs of infection begin within 5 five days following exposure, with 80% of newly infected animals exhibiting warning signs of the illness. While most exposed to the virus will only develop a mild case of CIV, some may become very sick. Signs to watch for include:

• Coughing. A main symptom, it may begin as a dry, raspy cough but will change to a wet, sputum-filled cough that often lasts for 10 days to several weeks.
• Sneezing and runny nose. This common symptom begins with a clear nasal discharge that changes to discharge that is thick, yellow, or tinged with blood.
• Diarrhea the consistency of water or gravy. This symptom may cause dehydration. The presence of blood in the stool requires immediate veterinary attention.
• Vomiting
• Lethargy
• Inappetence
• Fever. Mild cases will show low-grade fever, and severe cases will develop high fever.
• Shortness of breath
• Pneumonia

Testing for canine influenza virus

Serology should be completed to confirm a diagnosis of CIV infection and to rule out diseases with similar clinical signs, such as:

• Bordetella
• Coronavirus
• Canine herpes virus
• Parainfluenza
• Adenovirus

Diagnosis can be made through methods such as:

• Throat and nasal swabs samples taken from animals that have been ill less than 3 days
• Detection for influenza types A and B
• Antibodies to the CIV, as early as 7 days after onset of clinical signs.

Vaccines for CIV

Important information to know:

• Specific vaccines have been developed for separate use with both the H3N8 and the H3N2 strain of CIV
• A vaccine that combines both virus strains into one single vaccine is also available
• It is likely that in animals that have received CIV vaccinations, it will be possible to detect the antibodies associated with the virus
• The decision to vaccinate is largely based on the individual animal’s risk for exposure to the virus.

Highly contagious and potentially serious, canine influenza is rapidly affecting dogs across the United States.

The following articles may also be of interest:

Preventive Healthcare Can Grow Your Practice

Engaging, Educating Staff and Data Tracking

Contact your Covetrus representative for additional information on the H3N2 canine influenza virus at: 855.724.3461.

Source:
https://www.avma.org/KB/Resources/FAQs/Pages/Control-of-Canine-Influenza-in-Dogs.aspx

https://ahdc.vet.cornell.edu/news/civchicago.cfm