Dog with flu

Like humans, dogs are susceptible to the flu, a potentially serious respiratory illness that can be fatal in some cases.

While the flu is a relatively new disease in dogs, there is already a vaccine that can save many a dog's life. To learn all about the dog flu, its causes, its symptoms, and the best ways to protect your four-legged friend's health, I suggest we take a closer look at this particularly contagious disease in our article today.

 

What is dog flu?

Influenza in dogs is a respiratory disease caused by viruses commonly referred to as "influenza". It is considered a recent disease, as it has only been studied since the 2000s. Scientific interest in canine influenza was sparked by the transmission of a mutated influenza virus from horses to dogs in 2004 and again in 2005 in South Korea and the United States.

The context of the avian flu in 2007 had then made fear the occurrence of a real canine epidemic, first in racing greyhounds, the main concerned by the disease. Therefore, canine influenza is nowadays highly monitored, and it is likely that scientific knowledge about it will evolve in the years to come.

Several different viruses can cause dog flu, two of which have been formally identified: H3N8 and H3N2. It all starts with H3N8, a virus originally responsible for equine influenza, a serious disease that has been well known in the equine community for the past 40 years.

This pathogen appears to have made its appearance in the canine environment in 2004, when 22 racing greyhounds from the same dog track in Florida showed symptoms of a respiratory disease. Of these canine patients, 14 developed moderate disease, and 8 quickly died of severe respiratory disease (pulmonary hemorrhage, bronchiolitis, and suppurative pneumonia).

The tests first revealed the involvement of the H1N1 virus (influenza A), before identifying a mutation of the H3N8 equine influenza virus. In just two months, more than 10,000 dogs were affected in the United States. In 2005, 20,000 new dogs were affected, with an estimated mortality rate of 5% to 8%.

The H3N2 virus, on the other hand, is even newer, having been first identified in the United States in 2015 after an outbreak of respiratory disease in dogs in the Chicago area.

It is possible that this virus has its origins in Asia, a theory put forward after the death of a dog that succumbed to a form of acute influenza after eating ducks contaminated with bird flu (H5N1 virus) in Thailand.

At present, the possibility of cross-species contamination with H3N2 is suspected, especially after cats at an animal shelter were found to have contracted canine influenza in 2017. There is, however, no evidence that H3N2 or H3N8 is transmitted to humans.

 

 

 

Causes of dog flu

Canine influenza is transmitted mainly by aerosols, i.e. through droplets secreted in the air when the dog breathes, coughs, barks or sneezes. Also, contamination is mainly by direct contact from dog to dog, especially in confined spaces where there is a dense dog population. Shelters, kennels and groomers are recurrent sources of epidemics.

To a lesser extent, canine influenza viruses are also transmitted indirectly through contact with aerosol-contaminated objects (bowls, collars, leashes, etc.). People in contact with infected animals can also become vectors. In fact, while they may not be contaminated themselves and carry the virus itself, the virus may remain on their hands or clothing.

It is considered that the dog flu virus can survive for about 48 hours on surfaces, 24 hours on clothing and 12 hours on human skin. Dogs are most contagious during the incubation period of the virus. The incubation period is 1 to 5 days after infection for H3N8, and 2 to 8 days for H3N2.

It is important to note that the incubation period of the virus does not always result in clinical disease. Asymptomatic dogs can therefore be healthy carriers of the virus and contaminate other dogs who will be likely to develop a symptomatic form of the disease.

 

Symptoms of the dog flu

Symptoms of dog flu are mainly respiratory. Their virulence varies depending on the strain involved. The influenza virus affects the respiratory tract from the nasal cavities to the deep passages, i.e. the bronchi and lungs.

This results in an inflammatory response of varying degrees, which can lead to rhinitis (nasal cavities), tracheitis (trachea), bronchitis (bronchi) and bronchiolitis (bronchioles). The virus replicates in the epithelial cells (lining the mucous membranes) of the respiratory system, causing their destruction and abnormal exposure of the internal tissues of the various organs.

This breakdown of the epithelial tissue, which normally provides a barrier to pathogens, promotes bacterial superinfections, which are common in canine influenza. Approximately 80% of dogs infected with the influenza virus develop clinical symptoms, mostly in a mild form.

The mild form of canine influenza is manifested by coughing, sneezing, and thicker or thinner purulent nasal and ocular discharge from bacterial superinfections. The cough usually lasts between 10 and 21 days, despite veterinary treatment. The cough may be a wet, secretion-laden cough or a dry cough similar to kennel cough, which is different from influenza.

Lethargy and lack of appetite are also common, and most dogs also have a moderate fever (40°C to 40.5°C). In the severe form of the disease, dogs show signs of pneumonia, sometimes hemorrhagic, caused by bacterial superinfection.

The virulence of the disease can lead to a high fever (41°C) and the lobes of the lungs may be significantly damaged. If left untreated, this severe form of canine influenza is fatal in about 50% of cases.

 

 

Treatment and prognosis of the dog flu

It is essential to consult a veterinarian to treat a dog with the flu. However, as with most diseases caused by viruses, there is no treatment to eliminate the pathogen from the body. The treatment is therefore essentially intended to support the body during the illness and to control possible bacterial superinfections, which are responsible for the severe forms of the dog's flu.

Various drug therapies can be used to control the symptoms of dog flu, including coughing (cough suppressants), which can permanently destroy part of the lungs. The veterinarian may also decide to control the animal's fever and provide painkillers to relieve the pain that this disease can cause.

On a daily basis, the owner will need to monitor the dog's hydration and diet. The animal needs to rest and keep its strength up to stimulate its immune defenses and fight the virus. As a general rule, a dog with influenza recovers completely after two to three weeks of convalescence.

Quarantine is necessary to prevent the animal from infecting other dogs, and a sick dog should be confined to his home for four weeks. Usually, the prognosis for a properly treated dog is good, although recovery is always relatively long. The mortality rate from canine influenza is less than 10%.

 

Canine Flu Vaccine and Prevention

The good news is that there is a vaccine to protect dogs from the canine flu caused by H3N8 and H3N2. On the advice of your veterinarian, you can choose to give your pet both vaccines, or a single vaccine that protects against both strains of the virus simultaneously.

Vaccination reduces the risk of contamination, but also of developing severe forms of the disease. As a general rule, only dogs considered to be at risk are vaccinated against influenza, but nothing prevents other dogs from benefiting from this protection as well.

In addition to vaccination, it is recommended to implement barrier measures to limit the risks of contamination, especially in high-risk areas or situations. Therefore, after visiting a dog park, a puppy school, a kennel, a shelter, a veterinarian's office or a groomer's office, it is advisable to wash your hands and clothes and to clean your pet's leash and collar.

 

FAQ

What is dog flu?
Dog flu is a contagious viral respiratory disease caused by two different strains of virus. It causes symptoms similar to human flu, but is not transmitted from dogs to humans.

Is there a cure for the dog flu?
There is currently no treatment to eliminate the virus from a dog's body, but it is essential to consult a veterinarian when your pet seems to have the flu. It is essential to support your pet's body and control its symptoms, especially to avoid potentially fatal bacterial superinfections.

What is the difference between dog flu and kennel cough?
Dog flu is specifically caused by two types of influenza viruses, H3N8 and H3N2. Kennel cough, on the other hand, is usually caused by parainfluenza-like viruses. In this case, the two pathologies present sometimes very similar symptoms.

Can dog flu be transmitted to humans?
No, at this time there is no evidence to suggest that dog flu can be transmitted to humans. It can, however, be transmitted to cats, in whom it usually takes a mild to moderate form.

Dog flu is a disease that must be taken seriously, both to protect your four-legged friend properly and to avoid letting it become an epidemic. Preventive measures, including vaccination, are very effective in limiting the spread of this disease worldwide, and we recommend that you discuss this with your veterinarian, especially if your dog is considered at risk.

As a reminder, a dog is considered to be at particular risk of contracting the dog flu when it is in regular contact with a large number of other dogs, for example in dog parks, at the groomer's, in dog clubs or in a kennel.