The disease that brought a Multimillion rand horse industry to a halt!
By Johan Marais

Equine influenza is a major virus disease that causes Flu-like symptoms in horses and is from the group of viruses that causes flu in humans. The Influenza A/equi-2 virus causes most of the major disease outbreaks worldwide. It caused an epidemic in South Africa at the end of 2003, resulting in the cancellation of various horse races due to horses being "in bed with the flu".

The reason why people get the "flu" every year is because new strains of the virus causing the disease appear. The same scenario applies to the Nequi-2 viruses; it underwent something called "antigenic drift ". This resulted in two distinct lineages of the viruses, one called the North American lineage and the other the European lineage. The problem with the emergence of these two lineages is that strains from each lineage will not protect against the other lineage.

Does your horse have a runny nose?

The equine influenza damages respiratory cells along the full length of the respiratory tract, making the horse susceptible to secondary bacterial infections such as bronchitis, pleurisy or pneumonia.

Most horses exposed to the equine influenza virus (EIV) will show similar symptoms as the common "flu" as the virus damages the respiratory cells along the full length of the respiratory tract and will show signs within a period of one to four days, which include:

• Coughs
• Discharge from the nose
• Fever
• Dry, hacking and persistent cough
• Muscle soreness
• Depression
• Loss of appetite
• Lymph nodes become swollen and legs may have oedema
• Reluctancy to eat or drink for several days.

Remember that although vaccination helps to decrease the clinical signs associated with virus infection, vaccinated horses may continue to shed the virus for up to eight days after exposure.

This fact must be taken into account when reviewing quarantine protocols

Why does it spread like a veldfire?

It spreads by the inhalation of contaminated water droplets moving through the air and through contaminated objects like infected brushes, rugs equipment and clothing. The disease is very contagious and there is almost a 100% infection rate in a population that has been previously unexposed to the virus.

Can it be prevented and treated?

EIV is a virus and there are no drugs that influence the outcome of the disease. However many horses develop secondary infections with bacteria leading to pneumonia and other problems like heaves. Persistent coughing and limb oedema.

Good nursing care and if necessary. Antibiotics to deal with bacterial illness associated with the disease are important parts of treatment. Non-steroidal anti-inflammatory drugs may hasten the resolution of fever and nasal discharge. as well as limit weight loss. Bed rest is also the number one cure for the horse "flu".

Two weeks of rest to ensure proper healing of respiratory cells before resuming training is required for adequate recovery. Failure to rest completely may produce a persistent cough.

What can you do to prevent the spread of the disease?

The most important part of dealing with this illness is effective vaccination. Reasonably effective vaccines are now available featuring the two most important types of this virus but horses need to be vaccinated two to three times a year to ensure their immune status.

Vaccinations should begin at three months of age and be repeated a month later. Horses with minimal stress or exposure need only a yearly vaccination. Horses that are shown regularly or are constantly in contact with other horses should be vaccinated every three months.

VACCINATION SCHEDULES GUIDELINES

Any of the vaccines that meet the OlE International Standards two registered vaccines (Equilis Equenza T and Equine Influenza) and the three specially imported vaccines (Duvaxyn  IE Plus Equilis Influenza NN. ProteqFlu) can be used to vaccinate horses and will provide adequate protection against all recent equine influenza strains that have been isolated internationally.

PREVIOUSLY UNVACCINATED HORSES

a.  First equine influenza vaccination

b.  Second vaccination - 21 to 60 days after first vaccination

c.  Third vaccination - 120 to 180 days after second vaccination

d. Booster vaccinations - at intervals not exceeding six calendar months

REMEMBER

You can vaccinate horses against equine influenza at the same time as you vaccinate them against African horse sickness provided you inject the vaccines at different injection sites using separate syringes and needles

Previous vaccinated horses

Horses that have been vaccinated need to receive the vaccinations necessary to fulfill the requirements of the above schedule. If the horses have only received the vaccines that have since been discontinued, it is strongly advised that the horses be treated as previously unvaccinated horses.

FOALS BORN TO PREVIOUSLY UNVACCINATED MARES

Any mare that has not been vaccinated in the last six months is considered to be previously unvaccinated. Mares can be vaccinated at any time during pregnancy. These foals can be vaccinated from four weeks of age.

FOALS BORN TO PREVIOUSLY VACCINATED MARES

These foals should be vaccinated from four months of age.

REMEMBER

If the interval between the first and second vaccination is reduced to 14 days, the duration of immunity will be reduced and it will be necessary to give the first vaccination at approximately 90 days after the second vaccination