Canine Influenza Virus (CIV)

by Bruce W. Little, DVM

Canine Influenza Virus (CIV)

In the past two weeks, veterinarians have seen an unusually high amount of dogs infected by the canine influenza virus (CIV) in the Chicago area. More than 1,000 dogs were diagnosed with the disease, and 5 dogs died from the disease. The disease now appears to be spreading into downstate Illinois, Indiana and Wisconsin. It will likely spread into additional surrounding states in the near future. The disease is spreading so rapidly due to people traveling with their dogs. The virus remains active on clothing and hands for 24 hours, and remains active on hard surfaces for up to 48 hours.


The canine influenza virus was first discovered by veterinary scientists at the University of Florida in 2004. Chicago had a minor outbreak of the disease in 2008. The previous outbreak, however, did not infect nearly as many dogs as the current outbreak. CIV, also known as H3N8 influenza A, does not infect people even though CIV and the human strains of the influenza virus are both from the same influenza type A category. There have been no CIV documented cases in cats or other animals. Unlike seasonal flu in people, CIV is present all year and infects dogs of any age, breed, sex, or health status. The virus has a very high morbidity rate infecting as many as 80% of susceptible dogs that come into contact with the virus. Fortunately, the mortality or death rate is less than 10% for infected dogs.

An extremely virulent virus, CIV is highly contagious and spreads rapidly from infected dogs to vulnerable dogs through direct contact, nasal secretions, coughing and sneezing. The virus can also spread through contaminated objects, such as food, water bowls, collars, leashes, kennel surfaces and chew toys. People can also spread the disease from one dog to another. Dogs are most contagious in the early stages of the disease when the animal is not showing any symptoms, yet can spread the disease through secretions.


Symptoms of CIV begin with fever and may include lethargy, lack of appetite, coughing, nasal discharge and difficulty breathing. If untreated, the disease can progress into more serious respiratory diseases including pneumonia. If you observe any of these symptoms then it is important to keep your dog away from other dogs, and you should call your veterinarian immediately. CIV can be diagnosed early with a nasal swab test. The most accurate test is a blood test, which should be done during the first week of the illness and followed by a second sample 10 to 14 days later. Canine influenza resembles other canine respiratory infections such as, kennel cough or the Bordetella parainfluenza complex sometimes leading to kennel cough. Similar to other viral respiratory conditions, CIV predisposes dogs to secondary bacterial infections that can lead to complications like pneumonia and death.

Contain the Virus

The spread of CIV can be reduced by isolating sick dogs, as well as those who are exposed to the virus by an infected dog. It’s also important to isolate dogs showing any signs of respiratory illness. Remember to wash your hands, and clean any items that dogs share. All common disinfectants will work. These practices are essential to eliminating the spread of the disease.

Vaccinate Your Dog

Dogs kept in the house or in a fenced yard have a low risk for CIV exposure. Dogs that visit a public dog park, walking trails, dog spas, boarding and grooming salons have a higher risk for CIV exposure. Ask your veterinarian about the canine influenza vaccines that are available. The CIV vaccines are killed vaccines, and therefore a booster in about 10-14 days is needed as opposed to the human influenza vaccines that contain modified live viruses. 90% of vaccinated dogs are immune to CIV, but 10% of vaccinated dogs are still susceptible to CIV. If your pet does become infected after being vaccinated then the vaccine helps relieve the severity and duration of the illness. The vaccine also reduces the period of time that an infected dog is contagious, and thus reduces the likelihood that other dogs become infected with CIV.

Do not believe the false information being spread about the CIV vaccine being ineffective. The last CIV outbreak was in 2008 in Chicago. The current outbreak could have been prevented if all dogs born since 2008 were vaccinated. Consult your veterinarian to assess the specific needs of your dog and take all necessary precautions. Your dog will thank you for that trip to the vet, and hopefully it will prevent another outbreak.

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