Protecting Your Dog from Canine Influenza H3N8, Also Called CIV
Since about 2004, the canine influenza virus (CIV) has been spreading throughout the United States. This is a new and rare development since this virus was originally an equine influenza virus that has been transferred to dogs, and the virus adapted to dogs so that it has emerged as a new canine-specific virus. Although the virus spreads readily from dog to dog, there is no evidence to support that it can be transmitted from dogs to humans. However, note that humans can also transfer the virus from infected dogs to healthy dogs.
It appears that the virus outbreak of H3N8 occurred in racing greyhounds at a racetrack in Florida. Canine influenza is spread by way of aerosolized respiratory secretions and contaminated objects such as kennel surfaces, food and water bowls, collars and leashes and people moving between infected and uninfected dogs. The virus can survive on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours.
The incubation period is usually two to four days from exposure to onset of symptoms. During this time is when the dogs are most contagious--while they are not yet showing signs of illness. Virus shedding decreases dramatically during the first 4 days of illness but may continue for up to 7 to 10 days in some dogs.
Because this is a new virus, all dogs are susceptible to infection and have no naturally acquired or vaccine-immunity when first exposed to the virus. If the virus enters a kennel or other group of dogs, many of the dogs may become infected, and most of these dogs will have symptoms consistent with other respiratory illnesses. However, as many as 25 percent of infected dogs are expected to remain symptom-free, but are still contagious and able to spread the virus. Although most dogs have a milder form of canine influenza and recover without complications, some may develop severe pneumonia where it may become fatal.
The canine influenza virus infects and replicates inside the respiratory tract. The inflammatory response results in rhinitis, tracheitis, bronchitis and bronchiolitis. With the death of cells in the respiratory tract, secondary bacterial infections will contribute to nasal discharge and coughing.
CIV causes an acute respiratory infection in dogs, but unlike human influenza, CIV is not a seasonal flu and infections can occur anytime during the year--and the infection can be mild or severe. Canine influenza virus causes clinical disease that mimics kennel cough and is frequently mistaken for infections caused by the Bordetella bronchiseptica/parainfluenza virus complex.
The majority of infected dogs exhibit the mild form of influenza. In the mild form, the most common clinical sign is a cough that persists for 10 to 21 days despite treatment with antibiotics and cough suppressants. Most dogs have a soft, moist cough, whereas others have a dry cough that is similar to that induced by the Bordetella (kennel-cough) virus infection. Many dogs have a pus-like nasal discharge and a low-grade fever. The nasal discharge is usually caused by secondary bacterial infections. Some dogs are more severely affected with clinical signs of pneumonia, such as a high-grade fever (104°F to 106°F) and an increased breathing rate that is also labored.
Testing and Treatment
Testing to confirm canine influenza virus infection is available at most veterinary clinics. The tests is performed using respiratory secretions collected at the time of disease onset or using two blood samples with the first one collected while the animal is sick and the second 2 to 3 weeks later.
Treatment for your dog is largely supportive to help your pet mount an immune response. In the milder form of the disease, medication is administered to make your dog more comfortable and fluids to ensure that your dog remains hydrated. Broad spectrum antibiotics may be prescribed by your veterinarian if a secondary bacterial infection is suspected.
In May 2009, the USDA approved the first influenza vaccine for dogs developed by Intervet/Schering Plough Animal Health Corporation. The canine influenza vaccine contains inactivated whole virus.
The vaccine may not prevent infection altogether, but veterinary trials have shown that the vaccination may significantly reduce the severity and duration of the illness, including the severity of damage to the lungs. The vaccine also reduces the amount of virus shed and shortens the shedding interval so that vaccinated dogs that become infected will develop a less severe form of the illness and may be less likely to spread the virus to other dogs. This is similar to the protection provided by human influenza vaccines.
To date, there is no evidence that the canine influenza virus will spread to humans. The best thing to do is to get your dog vaccinated, especially if they are boarded often or socialize with other dogs.
Canine Influenza Fact Sheet- Iowa University