Canine Influenza (Dog Flu): An Overview

Dog Breeds

The canine influenza virus (CIV or Dog Flu) is a highly contagious, newly emerging pathogen in the dog population. The virus appears to have mutated from the equine influenza virus. Canine influenza virus infections can be mistaken for infections caused by Bordetella bacteria / Parainfluenza viruses, part of the traditional “kennel cough” complex.

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Introduction

The canine influenza virus (“CIV”) is a highly contagious, newly emerging, canine-specific infectious agent which represents an unusual adaptation of the equine influenza virus. In essence, the equine influenza virus mutated, jumped species and now lives, reproduces and spreads quite efficiently among – and so far only among - dogs. Early diagnosis and treatment can dramatically improve the chances of successful recovery and reduce further spread of the disease.

How Canine Influenza Affects Dogs

Unlike disease caused by the human flu virus, canine influenza is not seasonal and can occur in dogs of any age, gender or breed, at any time of the year. There is no natural or vaccine-induced immunity to this recently recognized pathogen. Clinical signs of “dog flu” typically appear suddenly. Most infected dogs have mild symptoms, including a persistent cough that can be moist or dry and usually lasts 2 to 3 weeks despite use of antibiotics and cough suppressants. The cough is accompanied by clear nasal drainage, which often progresses to a thick, greenish discharge. Low-grade fever is common. If the cough is dry and hacking, it may be confused with “kennel cough,” a condition caused by the Bordetella bronchiseptica/Parainfluenza virus that in the early stages is virtually indistinguishable from CIV infection.

In severe cases, dogs develop a high-grade fever and pronounced signs of pneumonia. Thankfully, the fatality rate for canine influenza is low.

Causes of Canine Influenza

“Dog flu” is caused by infection with the canine influenza virus. CIV is transmitted by inhalation of airborne respiratory secretions that contain viral particles. It can also be transmitted by direct contact with contaminated objects or surfaces. Reports suggest that the virus can survive in the environment and be infectious for up to 2 days. Given its mode of transmission, CIV tends to infect dogs that are in close contact with other dogs, as in boarding kennels, rescue shelters, humane societies, day-care facilities, dog shows or similar tight-group situations. Almost all exposed dogs become infected, and roughly 80% of infected dogs will develop signs of illness within several days.

Prevention and Control of Canine Influenza

The canine influenza virus seems to be easily killed by common disinfectants, making good hygienic practices the first and best line of prevention. Dogs that have been exposed to sick dogs or that are showing clinical signs of respiratory distress should be isolated from other dogs until those signs resolve. Owners of dogs that are coughing should restrict their own contact with other dogs. The first canine influenza virus vaccine was approved for licensure by the USDA in May of 2009 and is available to help control clinical disease.

Special Notes

If your dog shows signs of coughing, nasal discharge and a moderate fever, contact your veterinarian immediately. Because CIV is so highly contagious, other dogs in the household are at high risk for developing the disease. Until you find out what is causing your dog’s symptoms, keep it isolated from other dogs and always wash your hands thoroughly after petting or touching your dog.

Preventing Canine Influenza (Dog Flu)