Horse News & Views - December 2002

Ministry of Agriculture, Food and Rural Affairs

Ontario Association of Equine Practitioners

• Three Standardbred yearlings that died recently were submitted to the Animal Health Laboratory, University of Guelph, for diagnostic testing. The horses had a history of pyrexia (high temperature) of a few to several days duration, followed by acute-onset of difficult breathing and weakness that progressed to death within several hours. All animals were recently purchased from a public sale. Some of these animals were reported to be vaccinated. The cause of death is reported to be equine herpes virus. Equine herpesvirus type 1 (EHV-1) is most commonly associated with abortions in pregnant mares. Equine herpesvirus type 4 (EHV-4), also known as equine viral rhinopneumonitis or EVR, is commonly associated with respiratory disease. A neurological form can also be seen, which might resemble other diseases, including rabies, West Nile, EPM and wobblers. Vaccines are available for EHV, but quarantining animals returning from a sale or exhibition will reduce the risk of an abortion storm in pregnant mares or a respiratory disease outbreak in the horses on the home farm.
• The stems and leaves of red clover are covered with fine hairs that, when dried, result in dusty hay. Even in a hay mix with timothy, the hay is difficult to make, cures up quite brown and is slow to dry. This increases the chances of making a dusty, moldy hay, particularly during unfavourable weather conditions.
• Ringworm is occasionally seen on horses and can spread to people. The fungal spores can remain infectious for more than 12 months and spread to horses during wet warm weather. Prevention of outbreaks includes good nutrition, not sharing grooming equipment, keeping infected horses isolated and treating clinical signs.