NOTICE TO TRAINERS

Queensland Racing Limited was informed last evening of several cases of the Hendra Virus at a Redland’s Veterinary practice.

The local area has been locked down with 37 horses quarantined that are undergoing testing for the virus. It is likely that four horses were affected by the virus; three of the four horses have died, with one horse recovering.

The area is currently quarantined, and given recent advice, the outbreak is not expected to have any significant impact and should not pose any risk to the thoroughbred racing industry.

Set out below is an overview of the virus and connections are reminded of their obligation to report any incidence of the Hendra Virus, as a matter of urgency.

Hendra Virus Clinical Signs
Disease in equines caused by Hendra Virus (HeV) is a rare but potentially life-threatening disease.

Since first becoming apparent in 1994, it is now clear that the virus occurs rarely and sporadically in horses.  It occurs as a spill over infection from the virus's normal wildlife host, the flying fox. 

On only two occasions has there been apparent horse-to-horse spread.  One horse appears to have been infected from another horse in a situation where it had immediate contact with the dead horse.  In a separate outbreak, spread to several other horses occurred after a single sick mare was brought into stables from an open paddock.  In this case, within the stables, the pattern of spread suggests some form of mechanical transmission.

This means that this virus is unlikely to spread rapidly or easily between horses.
The virus has also spread from affected horses to four humans (two of these as fatal infections).  All four infected humans have had close contact with sick or dead horses.  Close contact with HeV infected body fluids, particularly blood and thoracic fluid from an infected horse can cause infection in humans.

HeV causes a broad range of clinical signs in horses:

The disease in horses is much more likely to occur as a single sick or dead horse than as a number of affected horses.  Clinical signs include the rapid deterioration of a horse in a paddock situation over a one to two day period with fever and signs of distress that have a respiratory system origin.  After death, the discharge of large quantities of froth from the nose or mouth and other indications of severe pulmonary oedema are clear indications of the possibility of Hendra virus disease.

HeV may be involved if a peracute or acute illness is seen in one or more animals in conjunction with:

• respiratory distress;
• frothy nasal discharge;
• elevated body temperature (above 40°C); or
• elevated heart rate (increased to around 90 or 100 beats/minute).

Note: at least 3 of these signs must be present within 24 hours of the onset of illness to be considered a 'possible' case.

In addition to those listed above, other signs that increase the likelihood of HeV being present are:

• facial oedema;
• terminal bloody nasal discharge;
• neurological signs - two horses that recovered had mild neurological signs, including muscle twitching.  (Neurological signs may be due to either encephalitis or vascular infarcts in the brain.)

In contrast to the above clinical signs, it appears that horses in the current outbreak are showing no respiratory signs, but instead neurological signs are predominating.
Clinical signs that are occurring in the current outbreak are:

• staggering;
• head pressing;
• demented behaviour;
• sudden, unexplained death (reported to be 3 out of 4 affected horses).

MR MALCOLM TUTTLE
Chief Operations Manager

End.