Canine Influenza has been in the news recently due to a widespread outbreak in the Midwestern United States. Here is some information to help you understand the disease.
What is canine influenza?
Canine influenza is a highly contagious respiratory infection caused by an Influenza Type A virus. Genetic analysis shows that the canine influenza virus is closely related to equine influenza virus, suggesting that it evolved from equine influenza virus and jumped species.
What is the clinical disease associated with canine influenza virus?
Two clinical syndromes have been seen in dogs infected with the canine influenza virus–a mild form of the disease and a more severe form that is accompanied by pneumonia.
The mild form. Dogs generally present with a soft, moist cough that persists for 10 to 30 days. Some dogs have a dry cough similar to kennel cough, resulting in mistaken diagnosis of this disease. Dogs with the mild form of influenza may have a secondary bacterial nasal discharge. As with other kennel cough infections the clinical signs are generally mild, the disease resolves without treatment, and treatment does not noticeably alter the course or duration of the disease. The value of antiviral therapy is not scientifically established.
The severe form. Dogs with the severe form of canine influenza develop high fevers (104°F to 106°F) and have clinical signs of hemorrhagic pneumonia (coughing up of blood). Secondary bacterial pneumonia may also be present.
Which dogs are susceptible?
Virtually all dogs are susceptible because immunity has not developed in the canine population at large. Somewhere between 50-80% of infected dogs show clinical signs of disease, mostly the mild form.
Is the disease geographically limited?
The disease was first identified in racing greyhounds in Florida in 2004. However, it has been reported in virtually all states within the United States. There have been 3 positive cases in Washington state between January 2005 and March 2015. (Cornell University Animal Health Diagnostic Center)
How is a dog with canine influenza treated?
The mild form requires minimal supportive treatment, as is the case with most mild upper-respiratory infection. Anti-cough medication may be provided. Antibiotic therapy should be restricted to high-risk patients.
Is canine influenza virus transmissible from dogs to humans or other animals?
Although the potential exists (as is evidenced by the cross-over of species from equine to canine, or the recent experience with avian influenza), there is no current concern of transmissibility to humans or other animals.
What about the canine influenza vaccine?
In 2009 a killed influenza vaccine was released. This vaccine has been claimed to limit clinical signs in dogs subsequently infected with canine influenza, but does not prevent infection or shedding of the virus from infected dogs. The vaccine might reduce the severity and duration of infection and clinical signs, but will not prevent infection. Given the limited spread of influenza through the general canine population in the US, and the relatively small percentage of dogs in whom the disease is more than a mild respiratory problem, current recommendations from veterinary consultants are to limit vaccinations to dogs that have a high risk of exposure.