Dog Flu (Canine influenza) is an emerging threat to all dogs.
Canine influenza is a relatively new disease commonly referred to as “dog flu,” and can be caused by two different canine influenza viruses. Just like human flu is among humans, canine influenza is highly contagious among dogs. In fact, unless a dog has already had the illness and recovered, almost every dog exposed to the virus will become infected.
Two different strains of canine influenza virus have been isolated in the US. H3N8 was first reported in 2003, and H3N2 emerged in March 2015. These strains are not related. Therefore, dogs at risk should be vaccinated against both strains. This is because the viruses are relatively new, and dogs have no natural immunity to it.
Dog Flu is Easily Transmitted from Dog to Dog
Canine influenza viruses H3N8 and H3N2 cause respiratory infections in dogs that are often referred to as “dog flu.” The viruses are relatively new, so almost all dogs are susceptible to infection when they are newly exposed because they have not built up natural immunity. Most dogs that develop CIV infections caused by either virus have a mild illness, but some dogs get very sick and require treatment in a veterinarian’s office.
Canine influenza is very contagious, meaning it is easily spread from dogs that are currently infected to healthy dogs. CIV is most commonly spread:
- Dog to dog direct contact (sniffing, licking, nuzzling)
- Through the air (coughing and sneezing)
- Via contaminated surfaces (sharing water bowls or toys)
- Through contaminated humans (with viruses on their hands or clothing)
Signs of Canine Influenza Infection
Be alert for the following signs, which are common in dogs with canine influenza:
- Mild, low-grade fever
- Lethargy (tiredness)
- Loss of appetite
- Cough, which may be dry or may bring up sputum
- Runny nose with clear secretions at first, but may later change to a thick and yellow and/or pink-tinged color
If your dog shows any of these signs, contact your veterinarian and avoid taking the dog anywhere that other dogs may be exposed (other than the veterinarian's office, if so instructed) until it has made a full recovery.
Of those dogs exposed, the following statistics regarding the general course of illness have been reported:
- Between 80 to 90% will develop clinical infection
- About 10 to 20% will become infected but will not show any signs; however, these dogs can still pass the virus to other dogs
- Most dogs will have a mild disease course
- Up to 20% of dogs may develop a more severe form, with a high fever (104-106°F) and pneumonia; these dogs must usually be admitted to the veterinary clinic for treatment
- Up to 8% of dogs may die from complications of CIV infection
Spread of CIV
- H3N8 has spread to at least 42 states, including Texas, since it was first reported in 2003
- H3N2 has already spread to at least 30 states, including Texas, since it was first reported in the U.S. in March, 2015.
You can help prevent the spread of canine influenza by vaccinating your dog, since vaccines are available.
If your dog has any of the signs of CIV infection, you should consider the following:
- Keep him or her home and avoid activities where other dogs can be exposed while the dog is coughing or exhibiting other signs of respiratory disease, for at least 2 weeks.
- Keeping your dog’s toys and food and water bowls clean with soap and water can also help prevent spread of the disease. You should disinfect your hands (with soap and water or an alcohol-based hand sanitizer) and wash clothing after exposure to dogs that have signs of respiratory disease to avoid transmitting infection to other dogs.
- Knowledge and common sense are your best defenses against canine influenza, so be aware of any information about outbreaks of canine influenza in your area, and take appropriate precautions.
Treatment of CIV Infection
If your dog has signs of canine influenza, keep him or her at home for the protection of other dogs, and contact your veterinarian regarding appropriate care and evaluation. There is no treatment specifically for CIV infection. Therefore, prevention through effective vaccination is very important. Vaccines against canine influenza viruses H3N8 and H3N2 are available through Houston Humane Society’s Animal Wellness Clinic. For dogs that do contract canine influenza, the focus of treatment is to provide supportive care while the infection runs its course. Dogs with mild infection may not require any intervention. Some dogs develop a more serious course and may require hospitalization for administration of intravenous fluids, supplemental feeding, and other supportive measures. Dogs that develop pneumonia may require antibiotics for secondary bacterial infection. Consult your veterinarian and discuss any questions or concerns you have about treatment.