The disease is caused by strains of the
influenza virus type A, which is akin, but not identical, to the
human influenza virus. The good news is that equine influenza cannot
be transmitted to humans, but the bad news is that it is highly
contagious – in fact, one of the most contagious diseases affecting
the British horse population – and can be physically carried by
human skin, hair and clothing, as well as by equipment and vehicles.
The equine influenza virus infects the
thin, membranous tissue of the upper respiratory tract, causing them
to become inflamed and ulcerated. Aside from an abnormally high body
temperature, the main clinical signs of equine influenza are a harsh,
dry cough – which is the main means by which the disease spreads –
and a profuse, watery nasal discharge. The damage areas in the lining
of the airways may be penetrated by bacteria, causing secondary
infections, including bronchitis and pneumonia.
The treatment of uncomplicated cases of
equine influenza consists of strict rest, usually for a week or two,
to allow the disease to run its course, but secondary bacterial
infections require antibiotic treatment, delaying the recovery
period. Clearly, equine influenza has major economic implications for
owners, trainers and anyone else involved in horse racing in Britain,
so despite complaints from some quarters – not least trainer Nigel
Twiston-Davies, who described the measures to contain the disease put
in place by the British Horseracing Authority (BHA) as a ‘massive
overreaction’, the regulator has every right to be nervous. With the Cheltenham Festival and Grand National just around the corner let me hope that the situation improves over the coming days.
